Nontuberculous Mycobacteria in Florida


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Nontuberculous Mycobacteria in Florida
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1 online resource (236 p.)
Yarnell,Stephanie C
University of Florida
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Gainesville, Fla.
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Doctorate ( Ph.D.)
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University of Florida
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Medical Sciences, Immunology and Microbiology (IDP)
Committee Chair:
Johnson, Judith Ann
Committee Co-Chair:
Kane, Andrew
Committee Members:
Morris, John
Lauzardo, Michael


Subjects / Keywords:
atypical -- gis -- mycobacteria -- nontuberculous -- ntm -- qpcr
Immunology and Microbiology (IDP) -- Dissertations, Academic -- UF
Medical Sciences thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
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Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy NONTUBERCULOUS MYCOBACTERIA IN FLORIDA By Stephanie C. Yarnell August 2011 Chair: Judith Johnson Major: Medical Sciences- Immunology and Microbiology Nontuberculous mycobacteria (NTM) are ubiquitous in the environment, including within municipal water distribution systems. Incidence of NTM infections in humans has dramatically increased over the past 20 years, with the number of NTM cases exceeding that of tuberculosis cases within the United States. NTMs such as M. avium, M. kansasii, M. xenopi, M. scrofulaceum, and M. marinum, have been associated with pulmonary disease, bone and soft tissue disease, as well as disseminated diseases. Disseminated infection is primarily due to Mycobacterium avium complex (MAC), an opportunistic bacterial infection. Disseminated MAC is most commonly found in immunocompromised patients, such as those with HIV-1, organ transplant recipients, persons with kidney or liver failure, or the elderly and is associated with significant mortality in these persons. Incidence of pulmonary NTM infections is also increasing in otherwise healthy subjects with the majority of clinical isolates associated with environmental sources. The primary route of NTM infection is believed to be water through ingestion or inhalation of aerosolized water colonized with mycobacteria. This lead me to hypothesize that some environmental parameter(s) are likely affecting the species distribution and density of mycobacteria in the environment, and that changes in these parameters may affect the number and diversity of mycobacteria in an area thereby altering the relative risk to the general population for NTM infections. In this study, a novel qPCR assay was designed for both the genus mycobacteria and MAC organisms and was used for detection of NTM prevalence and load. Field samples from both surface waters and municipal systems pre- and post-treatment demonstrated the ubiquitous presence of NTMs and MAC within these systems, although MAC loads were very low. Water quality analysis indicated various parameters may play a role in the diversity of these organisms within both surface and municipal water distribution systems. Demographical trends of persons hospitalized with pulmonary or disseminated NTM were also analyzed in this study. Our results indicate pulmonary NTM disease was more common in elderly, white females while disseminated NTM disease was more common in middle- aged, African American males. To analyze these trends further, home zip codes of persons hospitalized with pulmonary or disseminated NTM disease were mapped. Results of this exercise demonstrate the majority of persons with either pulmonary or disseminated NTM disease lived in urban areas. Combining this with the presence and growth of these bacteria in municipal sources, it stands to reason that municipal sources may provide a means for the distribution of these organisms to households throughout the study area, and may serve as a source of infection for high-risk patients.
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by Stephanie C Yarnell.
Thesis (Ph.D.)--University of Florida, 2011.
Adviser: Johnson, Judith Ann.
Co-adviser: Kane, Andrew.
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2 2011 Stephanie C. Yarnell


3 To my pa rents, Howard and Donna Yarnell


4 ACKNOWLEDGMENTS I would like to thank the members of the Emerging Pathogens Institute for their help Youliang Qiu, Jason Blackburn, Kevin Fennelly, Michael Lauzardo, Judith Johnson, Glenn Morris, and Andrew Kane, as well as, the present and past members of the Marine Animal Disease Laboratory for their help Linda Archer, Jim Wellehan and Hendrik Nollens This work could not have be en done without them. Stephen Hsu and Skip Harris deserve additional thanks for the immense moral support. Funding for this project was provided, in part, by an Opportunity Fund Award (Project Number 00091337) from the University of Florida, Office of Res earch, the University of Florida E merging Pathogens Institute, the College of Public Health and Health Professions and the MD/PhD Program Further technical support was provided by Steve McNulty, Barbara Elliott, Linda Bridge, Ravikiran, and Richard Wall ace of the University of Texas, Tyler, Texas. I thank my committee for their mentorship my chair, Judith Johnson, and Glenn Morris, Andrew Kane, Michael Lauzardo, as well as the IDP representative, Richard Condit. My parents, Howard and Donna, deserve s pecial thanks for being incredibly supportive as I continue down my seemingly endless educational path.


5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 8 LIST OF FIGURES ................................ ................................ ................................ .......... 9 LIST OF ABBREVIATIONS ................................ ................................ ........................... 10 ABSTRACT ................................ ................................ ................................ ................... 13 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 15 General Background ................................ ................................ ............................... 15 Cell Structure ................................ ................................ ................................ .......... 16 Medical ................................ ................................ ................................ ................... 19 Respiratory Infections ................................ ................................ ....................... 21 Hypersensitivity Pneumonitis ................................ ................................ ............ 25 Cystic Fibrosis (CF) ................................ ................................ .......................... 26 Disseminated Disease ................................ ................................ ...................... 28 Immunology ................................ ................................ ................................ ...... 31 Soft tissue/ Cutaneous Manifestations ................................ ............................. 33 Buruli Ulcer ................................ ................................ ................................ ....... 34 Traumatic Wound/ Surgery ................................ ................................ ............... 36 Chronic Bowel Disease ................................ ................................ .................... 38 Cervical Lymphadenitis ................................ ................................ .................... 42 Wildlife and Veterinary Diseases ................................ ................................ ...... 43 Intracellular Growth ................................ ................................ .......................... 45 Environmental Distribution ................................ ................................ ...................... 46 Water ................................ ................................ ................................ ...................... 48 Water Quality ................................ ................................ ................................ .......... 50 DOC ................................ ................................ ................................ ................. 51 Salt Tolerance ................................ ................................ ................................ .. 51 Dissolved Oxygen ................................ ................................ ............................ 52 Temperature ................................ ................................ ................................ ..... 53 pH ................................ ................................ ................................ ..................... 54 Drinking Water ................................ ................................ ................................ ........ 55 Geographical Mapping ................................ ................................ ............................ 65 Final Thoughts ................................ ................................ ................................ ........ 67


6 2 NONTUBERCULOUS MYCOBACTERIA DETECTED USING NOVEL QPCR PROBES ................................ ................................ ................................ ................. 69 Background ................................ ................................ ................................ ............. 69 Materials and Methods ................................ ................................ ............................ 71 Primer Development ................................ ................................ ......................... 71 Serial Dilutions ................................ ................................ ................................ 73 Extraction by Physical Disruption ................................ ................................ ..... 74 Extraction by Chemical Disruption ................................ ................................ .... 75 Comparison of qPCR and Traditional PCR ................................ ...................... 75 Results ................................ ................................ ................................ .................... 75 Primer Sensitivity and Specificity ................................ ................................ ...... 75 Chemical versus Physical Disruption ................................ ............................... 76 Culture Confirmation ................................ ................................ ........................ 76 Comparison of qPCR and Traditional PCR ................................ ...................... 77 Discussion ................................ ................................ ................................ .............. 77 3 NONTUBERCULOUS MYCOBACTERIA IN FLORIDA SURFACE AND MUNICIPAL WATERS ................................ ................................ ............................ 86 Background ................................ ................................ ................................ ............. 86 Materials and Methods ................................ ................................ ............................ 87 Sampling for Mycobacterial DNA ................................ ................................ ...... 88 DNA Extraction ................................ ................................ ................................ 88 Quantitative PCR (q PCR) ................................ ................................ ................ 88 Conformation of Near Threshold qPCR Data ................................ ................... 89 Culture Confirmation ................................ ................................ ........................ 90 Water Chemistry ................................ ................................ ............................... 91 Statistics ................................ ................................ ................................ ........... 91 Results ................................ ................................ ................................ .................... 91 Quantification ................................ ................................ ................................ ... 91 PCR and Sequencing ................................ ................................ ....................... 92 Culture Confirmation ................................ ................................ ........................ 93 Water Quality ................................ ................................ ................................ .... 93 Discussion ................................ ................................ ................................ .............. 94 4 DEMOGRAPHICS OF NONTUBERCULOUS MYCOBACTERIA CASES IN FLORIDA, 2006 2008 ................................ ................................ ........................... 104 Background ................................ ................................ ................................ ........... 104 Materials and Methods ................................ ................................ .......................... 106 Data Source ................................ ................................ ................................ ... 106 Data Analysis ................................ ................................ ................................ 107 Multivariate Analysis ................................ ................................ ....................... 107 Results ................................ ................................ ................................ .................. 108 Pulmo nary NTM ................................ ................................ ............................. 109 Disseminated NTM ................................ ................................ ......................... 111


7 Discussion ................................ ................................ ................................ ............ 112 Age ................................ ................................ ................................ ................. 112 Gender ................................ ................................ ................................ ........... 114 Race ................................ ................................ ................................ ............... 115 Seasonality ................................ ................................ ................................ ..... 116 Payer Status ................................ ................................ ................................ ... 117 Length of Stay ................................ ................................ ................................ 117 Co illnesses ................................ ................................ ................................ .... 118 Incidence ................................ ................................ ................................ ........ 122 Multivariate Analysis ................................ ................................ ....................... 123 Final Thoughts ................................ ................................ ................................ 124 5 SPA TIO TEMPORAL PATTERNS OF REPORTED NONTUBERCULOUS MYCOBACTERIA CASES IN FLORIDA, 2006 2008 ................................ ............ 136 Background ................................ ................................ ................................ ........... 136 Overview ................................ ................................ ................................ ........ 136 Geospatial Analysis ................................ ................................ ........................ 138 Materials and Methods ................................ ................................ .......................... 140 Data Source ................................ ................................ ................................ ... 140 Data Analysis ................................ ................................ ................................ 141 Confidentiality ................................ ................................ ................................ 141 Smoothing ................................ ................................ ................................ ...... 143 Spatial A nalyses ................................ ................................ ............................. 143 Results ................................ ................................ ................................ .................. 144 Spatial Distribution of Pulmonary NTM ................................ ........................... 144 Spatial Distribution of Disseminated NTM ................................ ...................... 145 Clustering of NTM Hospitalization ................................ ................................ .. 146 Pulmonary NTM Hospitalizations ................................ ............................. 146 Disseminated NTM Hospitalizations ................................ ........................ 148 Discussion ................................ ................................ ................................ ............ 149 Incidence ................................ ................................ ................................ ........ 150 Cluster Analysis ................................ ................................ .............................. 153 Final Thoughts ................................ ................................ ................................ 156 6 FINAL CONCLUSIONS ................................ ................................ ........................ 163 Overview ................................ ................................ ................................ ............... 163 Final Tho ughts ................................ ................................ ................................ ...... 174 APPENDIX: SEQUENCE RESULTS OF CULTURED BACTERIA ............................. 176 LIST OF REFEREN CES ................................ ................................ ............................. 180 BIOGRAPHICAL SKETCH ................................ ................................ .......................... 236


8 LIST OF TABLES Table page 2 1 CFU and calculated CFU for serial dilutions of mycobacterial cultures. ............. 80 3 1 Water quality data, pan bacterial counts, mycobacteria counts and percentage mycobacteria from m unicipal and environmental water samples. .... 99 3 2 Comparison of estimated total bacterial and mycobacterial counts from aquifer source water (pre treatment) and municipally distributed water (p ost treatment) from two municipal distribution systems. ................................ ......... 100 3 3 Range of environmental bacterial counts (total bacteria and mycobacteria) reported from previous studies. ................................ ................................ ........ 101 4 1 Co illnesses associated with pulmonary NTM disease ................................ ..... 126 4 2 Co illnesses associated with disseminated NTM disease. ............................... 127 4 3 Significant results of the multivariate analysis. ................................ ................. 128 5 1 Caseload, zip codes (zips) reporting, incidence for both raw and smoothed data, and maximu m incidence noted in any given zip code for pulmonary and disseminated NTM ................................ ................................ ............................ 157


9 LIST OF FIGURES Figure page 2 1 Genus Specificity Curves.. ................................ ................................ ................. 81 2 2 MAC Specificity Curve. ................................ ................................ ....................... 82 2 3 Standard Curves. ................................ ................................ ................................ 83 2 4 Traditional PCR Results. ................................ ................................ .................... 84 2 5 qPCR Results. ................................ ................................ ................................ .... 85 3 1 Estimated counts of total bacteria, mycobacteria, and MAC based on qPCR determination o f number of DNA copies. ................................ .......................... 102 4 1 Racial distribution of pulmonary versus disseminated NTM hospitalizations. ... 129 4 2 Racial distri bution of pulmonary versus disseminated NTM normalized yearly incidence rates. ................................ ................................ ................................ 130 4 3 Age and gender distributions of pulmonary NTM ................................ .............. 131 4 4 Normalized yearly incidence distributions broken down by age and gender for pulmonary NTM ................................ ................................ ................................ 132 4 5 Age and gender distributions of disseminated NTM ................................ ......... 133 4 6 Normalized yearly incidence distributions broken down by age and gender for disseminated NTM ................................ ................................ ............................ 134 4 7 Payer status for patients hospitalized with either pulmonary or disseminated NTM disease. ................................ ................................ ................................ ... 135 5 1 Reference map of Florida showing major roadways, cities, and water systems. ................................ ................................ ................................ ........... 158 5 2 I ncidence maps of pulmonary NTM disease, 2006 2008, with and without HIV co illness. ................................ ................................ ................................ ... 159 5 3 Incidence maps of disseminated NTM disease, 2006 2008, with and without HIV co illness. ................................ ................................ ................................ ... 160 5 4 LISA maps showing cluster analyses of pulmonary NTM disease, 2006 2008, with and without HIV co illness. ................................ ................................ ........ 161 5 5 LISA maps showi ng cluster analyses of disseminated NTM disease, 2006 2008, with and without HIV co illness. ................................ .............................. 162


10 LIST OF ABBREVIATION S A adenosine A HCA Agency for Healthcare Administration AIDS acquired immune deficiency syndrome A OC a ssimilable organic carbon A PHA American Public Health Association BALF bronchoalveloar lavage fluid BCG Bacille Calmette Gurin vaccine Bp base pairs C cytosine CD CD4 cluster of differentiation 4, T helper cells CDC Center for Diseas e Control and Prevention CET cryo electron tomography CF cystic fibrosis CFU colony forming unit CO 2 carbon dioxide COPD chronic obstructive pulmonary disease CPC cetylpyridinium chloride Ct threshold cycle DMSO dimethyl sulfoxide DNA d eoxyribonuc leic acid DO dissolved oxygen DOC dissolved organic carbon dNTP deoxynucleotide triphosphates


11 E. coli Escherichia coli ELISA e nzyme linked immunosorbent assay EPA Environmental Protection Agency ESDA exploratory spatial data analysis 6 FAM 6 carbox yfluorescein label FL Florida G guanine GIS geographic information systems GPS global positioning system HAART highly active antiretroviral therapy HCl hydrochloric acid HIPAA Health Insurance Portability and Accountability Act HIV human immunodefi ciency virus HRCT high resolution computerized tomography Hsp heat shock protein ICD 9 international statistical classification of diseases and related health problems, 9 th revision IFN interferon gamma IRB institutional review board JD K + potassium ion LISA local indicator of spatial analysis MAC Mycobacterium avium complex MAP Mycobacterium avium subspecies paratuberculosis Na + Sodium ion NaCl Sodium c hlor ide


12 NaOH Sodium hydroxide NT M nontuberculous mycobacteria PCR polymerase chain reaction PPD B purified protein derivative B qPCR quantitative polymerase chain reaction (a.k.a. real time PCR) RNA r ibonucleic acid rRNA r ibosomal ribonucleic acid SDS PAGE sodium dodecyl sulfate polyacrylamide gel electophoresis SNTC Southeastern National Tuberculosis Center Ssp. subspecies T thymine TB tuberculosis TBB transbroncial biopsy TNF tumor necrosis factor alpha TE Buffer tris, EDTA Buffer US United States WHO World Health Organization YO year old


13 Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of t he Requirements for the Degree of Doctor of Philosophy NONTUBERCULOUS MYCOBACTERIA IN FLORIDA By Stephanie C. Yarnell August 2011 Chair: Judith Johnson Major: Medical Sciences Immunology and Microbiology Nontuberculous mycobacteria (NTM) are ubiquito us in the environment, including within municipal water distribution systems. Incidence of NTM infections in humans has dramatically increased over the past 20 years, with the number of NTM cases exceeding that of tuberculosis cases within the United State s. NTMs such as M. avium, M. kansasii, M. xenopi, M. scrofulaceum, and M. marinum have been associated with pulmonary disease, bone and soft tissue disease, as well as disseminated diseases. Disseminated infection is primarily due to Mycobacterium avium c omplex (MAC), an opportunistic bacterial infection. Disseminated MAC is most commonly found in immunocompromised patients, such as those with HIV 1, organ transplant recipients, persons with kidney or liver failure, or the elderly and is associated with s ignificant mortality in these persons. Incidence of pulmonary NTM infections is also increasing in otherwise healthy subjects with the majority of clinical isolates associated with environmental sources. The primary route of NTM infection is believed to be water through ingestion or inhalation of aerosolized water colonized with mycobacteria. This lead me to hypothesize that some environmental parameter(s) are likely affecting the species distribution and density of mycobacteria in the environment, and t hat changes


14 in these parameters may affect the number and diversity of mycobacteria in an area thereby altering the relative risk to the general population for NTM infections In this study, a novel qPCR assay was designed for both the genus mycobacteria and MAC organisms and was used for detection of NTM prevalence and load. Field samples from both surface waters and municipal systems pre and post treatment demonstrated the ubiquitous presence of NTMs and MAC within these systems, although MAC loads wer e very low. Water quality analysis indicated various parameters may play a role in the diversity of these organisms within both surface and municipal water distribution systems. Demographical trends of persons hospitalized with pulmonary or disseminated NTM were also analyzed in this study. Our results indicate pulmonary NTM disease was more common in elderly, white females while disseminated NTM disease was more common in middle aged, African American males. To analyze these trends further, home zip codes of persons hospitalized with pulmonary or disseminated NTM disease were mapped. Results of this exercise demonstrate the majority of persons with either pulmonary or disseminated NTM disease lived in urban areas. Combining this with the presence an d growth of these bacteria in municipal sources, it stands to reason that municipal sources may provide a means for the distribution of these organisms to households throughout the study area, and may serve as a source of infection for high risk patients.


15 CHAPTER 1 INTRODUCTION General Background Non tuberculous bacteria, or NTMs are mycobaceria of public heath and clinical importance. The genus Mycobacterium contains gram positive microaerophilic bacteria belonging to the family Mycobacteriaceae and i s one of several mycolic acid containing genera within the order Actinomycetes. Mycobacteria characteristically have genomic DNA with a high G C content, and the tendency toward causing chronic infections in humans (Howard and Byrd, 2000; Falkinham, 2003). More than 130 species have already been identified (Euzby 1997). Each isolate can be categorized into one of three groups based upon clinical significance. The first grouping includes the obligate pathogens; Mycobacterium tuberculosis complex ( M. afr icanum, M. bovis, M. canettii, M. caprae, M. microti, M. pinnipedii, and M. tuberculosis), M. leprae, and M. lepraemurium none of which are generally found in the environment. The second grouping contains those, such as M. avium (MAC), which are potentia lly pathogenic to humans and animals and are generally derived from aquatic and terrestrial environments. The third grouping consists of low virulence species which are often saprophytic. Together, groups 2 and 3 encompass the environmentally derived myc obacteria and are often referred to as tuberculous m (NTMs) (Vaerewijck et al., 2005).


16 Mycobacteria can be divided into fast growing (i.e., colony fo rmation in less than 7 days) or slow growing (i.e., colony formation requiring 7 days or more and including M. tuberculosis ) (Primm et al 2004). F ast growing mycobacteria grow significantly slower than typical bacteria, as NTMs often have generation times of one day or more in rich media (Bercovier et al., 1986). The slow growth of mycobacteria is directly related to possession of only one or two 16S rRNA cistrons, impermeability of the lipid rich cell wall, and the synthetic energy costs of the long chain mycolic acids, waxes, and lipids (C 60 C 80 ) (Rostogi et al., 1981; Brennan and Nikaido 1995; Primm et al 2004). These growth limiting charac teristics are not, however, without benefit. A single 16S rRNA cistron, for example, allows more time to adapt to a stressful environment and eases accumulation of resistance mutations to ribosomal targeting antibiotics (Primm et al., 2004). Cell Structur e Mycobacteria are the most hydrophobic bacteria (van Oss et al., 1975) and that serves as a major determinant of the environmental distribution (Primm et al 2004). Their innate hydrophobicity attracts nutrient sources and small organic compounds, allow s for adherence and thereby biofilm production, allows for phagocytosis by macrophages and protozoa, and allows for easy aerosolization which can then grant pulmonary access to animals and humans (van Oss et al., 1975; Strahl et al., 2001; Primm et al 20 04). The impermeability of the cell wall endows mycobacteria with an innate resistance to heavy metals and many antimicrobial agents, including antibiotics and disinfectants (Rastogi et al., 1981; Falkingham et al., 1984; Sanfranek et al., 1987; Pelletier et al., 1988; Best et al., 1990; Taylor et al., 2000; Miyamoto et al., 2000; Cangelosi et al.,


17 2001). NTMs, such as M. avium and M. intracellulare, exhibit heavy metal resistance, and are able to populate habitats that metalosensitive microorganisms canno t, allowing them to attach to the metal surface and serve as biofilm pioneers (Falkingham, 2010; Cook et al., 2010). The natural resistance to many antimicrobial compounds explains the presence of mycobacteria after standard disinfection procedures (Taylo r et al., 2000). The unique mycobacterial cell wall is also believed to play a crucial role in the infection, intracellular growth, and survival within animals and protozoa (Primm et al., 2004). Mycobacteria posses a unique cell envelope consisting of a c ytoplasmic membrane and a cell wall composed largely of mycolic acids and long chain fatty acids (Minnikin, 1982; Brennan and Nikaido, 1995; Barry, 2001; Rastogi et al., 2001). The mycolic acids are covalently linked to peptidoglycan by arabinogalactan fo rming a hydrophobic layer with other lipids (Nikaido et al., 1993; Minnikin et al., 2002). As it is typically arranged, linear galactan molecules are substituted into the peptidoglycan network with branched arabinose chains each ending in four arabinose d imers (Minnikin, 1982; Brennan and Nikaido, 1995). These arabinose dimers, in turn, form the head for two mycolic acid molecules (Minnikin, 1982). The inner leaflet of these mycolic acids are thought to function much like a second lipid bilayer (Minnikin 1982), and, in deed, recent studies involving cryo electron tomography (CET) and electron microscopy of ultra thin cryosections have confirmed the three dimensional structure of the bilayer structure of the cell envelope in mycobacteria (Hoffman et al., 2008; Zuber et al., 2008). This second, hydrophobic bilayer imparts impermeability to the cell envelope thereby excluding crystal violet dyes from staining the peptidoglycan layers. Thus, despite


18 being gram positive, mycobacteria are not gram stain posit ive (Barksdale and Kim, 1977). Upon heating, mycobacteria will retain acidic organic dyes, such as carbol fuchsin, and so mycobacteria exhibit acid fast staining (Barksdale and Kim, 1977; Minnikin, 1982). the bacterial world has been divided into two broad groupings, gram positive and gram negative organisms (Gram, 1884). Gram positive bacteria have typically been thought to have a thick cell wall composed of one layer consisting primarily of peptidoglycan (Bevridge, 2001). Gram negative bacteria, on the other hand, have a cell wall composed of two layers, a thin peptidoglycan layer and an overlying lipoprotein bilayer known as the outer membrane with an intervening periplasmic space (Bevridge, 2001). Myc obacteria seem to defy this breakdown, as they are classified as gram positive organisms based on their taxonomy, and yet their cell wall composed of mycolic acid arabinogalactan peptidoglycan polymers form a outer membrane similar to that of a gram negati ve bacteria (Hoffman et a l., 2008; Zuber et al., 2008). This observation means that mycobacteria have two subcellular compartments, a periplasmic space and an outer membrane, that other gram positives do not (Hoppert, et al., 1999; Morita et al., 2005), a nd is of importance functionally, as it produces complications in both uptake and secretion processes (Niederweis et al., 2010). Gram negative bacteria address this by embedding porins and other transport proteins into their membranes to ease the transfer of nutrients from the external environment into the cell (Bevridge, 2001). Indeed, Escherichia coli, a well studied gram negative bacteria, employs more than 60 outer membrane proteins, most forming channels for the transport of nutrients (Molloy et al., 2000; Nikaido, 2003).


19 Similarly, mycobacteria have been found to contain porins (Trias et al., 1992; Niederweis et al., 1999), and genome studies of M. tuberculosis have revealed more than 140 putative outer membrane proteins (Song et al., 2008). Thus, mycobacteria appear to have characteristics of both gram positive and gram negative bacteria, and like gram negative bacteria, this outer membrane serves as a functional barrier to the uptake of exogenous compounds, including antimicrobials and disinfectan ts (Connell and Nikaido, 1994). The mycobacterial cell wall is characteristic for its complex array of hydrocarbon chains perforated by porins, as well as the electron dense peptidoglycan layer that is surrounded by a hydrophobic arabinogalactan peptidogl ycan mycolic acid layer (Belisle et al, 1991; Inderlied et al., 1993; Wayne et al., 1993; Belisle and Brennan 1994). The presence of fatty acids, lipids, and waxes in the cell wall are also determinants of mycobacterial hydrophobicity. Medical The bes t known pathogens in this group are M. tuberculosis and M. leprae K nown for over a century, M. tuberculosis the causative agent of tuberculosis (TB), is responsible for more human deaths than any other microbe (Koch, 1890; Kaufmann, 2011). Despite bein g curable by antibiotics in most cases, TB affects more than two billion people, with 9.3 million new infections and 1.3 million deaths each year (WHO, 2010; Kaufmann, 2011). Similarly, leprosy, caused by M. leprae was first identified in the 19 th centur y and is largely treatable with antibiotics, yet approximately 250,000 new cases are reported every year (WHO, 2008). NTMs too have their share in human and animal morbidity and mortality (Primm et al 2004). T he incidence of infection with NTMs in huma ns is on the rise, with the


20 number of isolates of NTMs from infectious material exceeding those of M. tuberculosis within the United States (Sood et al., 2007). The increase in number of reported cases has been attributed to a number of factors, including increased awareness of these microbes as human pathogens, improved detection and culture techniques increased proportion of the population that is elderly or immunocompromised, the ubiquitous presence of NTMs, increased exposure to heated water, increase d selection of mycobacteria by certain human activities, and the widespread use of disinfectants (Sood et al., 2007). Numerous studies have demonstrated the clinical significance of these NTMs in both immunocompromised and healthy patients (Vaerewijck et al., 2005). Members of the Mycobacterium avium complex (MAC), (comprising M. avium and M. intracellulare ), are responsible for the majority of NTM infections in developed countries with the main presentations being: lymphadenitis in children, respiratory infections in the elderly, and intestinal and disseminated disease in the HIV infected population (Horsburgh, 1996; Vaerewijck et al., 2005 ). NTMs also cause nosocomial outbreaks and mini epidemics, hypersensitivity pneumonitis, arthritis, keratitis, teno synovitis, otitis media, corneal infections, endocarditis, immunologic dysfunction, and chronic disease states ( Moore, 1993; Howard and Byrd, 2000; Vaerewijck et al., 2005). The clinical scenario is complicated, because NTM infections often present with v ague symptoms, such as fever, anorexia, weight loss, and night sweats. The vagueness of symptoms often delays diagnosis which is problematic because NTM infections are a primary cause of death among immunocompromised persons (Howard and Byrd, 2000).


21 Di agnosis is further complicated by the ability of these organisms to colonize individuals. NTMs can be isolated from saliva, sputum, urine, and gastric washings even when no disease is present. This appears to be particularly true for respiratory isolates as most persons from whom environmental mycobacteria were recovered from the airways of did not appear to be harmed (Howard and Byrd, 2000). Mycobacteria can also be found in the stool of healthy persons (Portaels et al., 1988). Further evidence for th e transient, regular exposure of humans to NTMs is the finding that over 60% of men from the Southeastern coastal region of the United States tested positive on PPD B, but showed no signs of disease. Thus, it is believed that they were exposed and produce d an immune response to mycobacterial antigens, but never developed outright disease (Edwards et al, 1969; Reed et al., 2006). Further, it has been demonstrated that United States medical personal have a high rate of environmental mycobacterial skin test reactivity with no history of disease (von Reyn et al 2001). The regular rates of exposure may be due largely to the ubiquitous nature of NTMs; humans are constantly and continuously exposed to environmental mycobacteria at low levels, but overt disease generally does not occur without one or more underlying medical conditions (Primm et al 2004). Despite their growing importance, little is known about how these infections are spread. Respiratory Infections M. tuberculosis is well known as a respirat ory pathogen and some NTMs are also capable of causing tuberculous like lesions (Vaerewijck et al., 2005). Indeed, t he second most common presentation of NTM infection is pulmonary manifestations and the incidence around the globe is increasing (Moore et al., 2010; Lai et al., 2010; Winthrop et al., 2010). The majority of reported pulmonary cases of NTM infection within


22 the United States were from Southern coastal states, such as Florida (Falkingham, 1996; Bilinger et al., 2009) which correlates with the increased rates of skin tes t reactions seen in this region (von Reyn et al 2001). In addition to granulomas and cavitary disease similar to that seen in TB, pulmonary disease from NTMs can take on a variety of clinico pathologic presentations including asymptomatic indolent disease, interstitial disease, or hypersensitivity pneumonitis like granulomatous lung disease. Lesions occur predominantly in the upper lobes of the lung especially in sites of pre existing mycobacterial or fungal disease or bronch iectasis (Howard and Byrd, 2000; Sood et al., 2007). Although the clinical presentation of pulmonary NTM resembles that of TB, this disease is very different in that the host acquires the infection from environmental sources such as water, which may expla in the predilection for warm coastal regions (Pedley et al., 2004). Indeed, NTMs are ubiquitous in the environment and exposure so common, that a finding of NTMs in respiratory secretions requires supportive clinical symptoms prior to beginning treatment (Griffith et al., 2007). These cases have caused many to wonder if colonization independent of disease occurs or if these findings simply demark subclinical disease likely to progress (Wang et al., 2009). Regardless of location, pulmonary NTM infections can be quite severe, carrying a mortality rate of 14% (Howard and Byrd, 2000). The classic presentation for NTM induced pulmonary infection is cavitary lung disease in white males above the age of 60 who have some form of predisposing lung disease and a history of smoking and alcohol abuse (Wolinsky, 1979). These predisposing conditions include pneumoconiosis, chronic obstructive pulmonary disease, cavitary lesions from previous TB or bronchiectasis, smoking, black lung,


23 occupations where large amounts of dust and particulates are inhaled, cystic fibrosis, radiation therapy to the lung, or malignancies of the lung (Falkinham, 2003). Many of these conditions result in scarring and fibrosis of the lung, which is believed to allow subsequent colonization by NTMs (McGrath et al., 2010). The classic presenting signs are cough with sputum production, but those may be accompanied by shortness of breath, dyspnea, hemoptysis, fatigue, lassitude, weight loss, fever, or night sweats. Radiographically, these case s typically manifest with pulmonary cavities, pleural thickening, nodular infiltrates, consolidation, and various forms of bronchiectasis (Griffith et al., 2007; Arend et al., 2009). Historically, these cases have been mistaken for TB, but the patient is not infectious to relatives or clinical staff. This does not diminish the seriousness of these infections as they can often progress to respiratory failure and death (Field and Cowie, 2006). Delays in proper diagnosis often occur because of difficult y d ifferentiat ing symptoms due to underlying lung disease, such as sputum production in bronchiectasis or dyspnea in emphysema, and symptoms derived from the superimposed mycobacterial infection (Griffith et al., 2007). Further complicating the care of these patients, respiratory secretions often harbor an array of organisms including mixed mycobacterial species, fungi, and other pathogenic bacteria making appropriate antibiotic selection more difficult (Pedley et al., 2004; Arend et al., 2009). Once identif ied, NTM induced pulmonary disease can be quite challenging to treat and may require surgical removal of the diseased tissue (Howard and Byrd, 2000). The epidemiology of NTM pulmonary disease appears to be shifting toward non smoking older females with no underlying lung disease. There is an increasing number of sub acute pulmonary cases presenting with respiratory complaints, dyspnea and


24 cough being most common, occurring in this population with a lack of occupational exposure to dusts or other known pred isposing conditions (Falkinham, 2003; Sood et al 2007; Cassidy et al., 2009). Th is trend first described in 1989 when Prince et al. observed that 81% of the patients were female, 86% were white, and the mean age was 66 years (Prince et al., 1989) has b een noted multiple times and represents a shift from male dominated secondary infection to a primary infection in these patients (von Reyn et al., 2001; Chalermskulrat et al., 2002; Cassidy et al., 2009). Infected persons are often thin, and correlations have been drawn to particular body phenotypes including narrowing of the anterior posterior diameter, pectus excavatum, and mitral valve prolapse (Iseman et al., 1991). These patients typically show no cavitary lung disease, but instead show fibronodular bronchiectasis (Field and Cowie, 2006). In reported cases of this nature, pulmonary function tests showed a restrictive lung disease, chest radiographs showed diffuse interstitial or nodular opacities, high resolution computerized tomography (HRCT) showed diffuse ground glass opacities and centrilobular ill defined micronodules in both lungs, bronchoalvelolar lavage fluid (BALF) showed modest lymphocytic predominance with a high CD4/CD8 ratio, culture yielded primarily M. avium, M. kansasii, or M. abscessu s and histopathologic findings of transbrochial biopsy (TBB) showed well formed, centrilobular and bronchiolocentric non necrotizing granulomas (Aksamit 2002; Chalermskulrat et al., 2002; Sood et al., 2007). The increase in fibronodular bronchiectasis i s thought to be in part due to fewer cases of TB hence fewer pre existing cavitations for the establishment of NTM disease, as well as the increase in elderly persons within the United States (Field and Cowie, 2006). This disease should not be taken li ghtly, however, as it can be fatal (Prince et


25 al., 1989). Left untreated the nodular bronchiectactic disease can cavitate causing severe, often permanent, lung damage (Griffith et al., 2007). Treatment can be difficult and relapse is common when therapy is stopped (Saleeb and Olivier, 2010). Given the general increase in incidence and susceptible patients, as the population continues to age, the prevalence of fibronodular bronchiectasis can be expected to continue to increase (Field and Cowie, 2006). Hyp ersensitivity Pneumonitis NTMs can infect recreational water supplies creating a risk for hypersensitivity pneumonitis. For decades it has been recognized that persons exposed to long term aerosolization from swimming pools (i.e. lifeguards) were at risk for granulomatous pneumonitis (Havelaar et al., 1985; Emde et al., 1992; Rose et al., 1998). This form of NTM disease often affects healthy, immunocompetent people with aerosol exposure to mycobacteria such as lifeguards and people using aquatic sources for recreation or work (Havelaar et al., 1985; Emde et al., 1992; Rose et al., 1998; Embil et al., 1997; Mangione et al., 2001; Mery and Horan 2002; Kang et al., 2010). While M. avium complex is the most commonly reported NTM in hot tub lung, it should b e noted that cases due to M. fortuitum have also been reported (Thompson and Yew, 2009). Hot tubs, indoor swimming pools, and spas, in particular, are linked to human infection (Embil et al., 1997; Kahana et al., 1997; Khoor et al., 2001; Kang et al., 201 0). Mycobacteria are not only capable of surviving and reproducing in swimming pools and hot tubs, but may even comprise a significant fraction of the microbes in these locations (Angenent et al., 2005). Aerosolization is believed to be the major route o f infection from these sources, as NTMs have been found in higher quantities in the air above pools than in the pool water itself (Angenent et al., 2005).


26 It is unclear at the present time whether this is due to a hypersensitivity to M. avium complex is associated with an actual infection, or is an immune mediated illness (Vaerewijck et al., 2005). The pathology is believed to be due to pulmonary macrophages processing and presenting the NTM antigens to T lymphocytes, inducing a clonal expansion and pro liferation, which in turn induces granuloma formation within the lung (Sood et al., 2007). This extensive granulomatous reaction indicates that the in this disease (Howar d and Byrd, 2000). Subsequent symptoms include cough, dyspnea, fatigue, impaired exercise tolerance, and sputum production ; and chest radiograph and computed tomography scans indicate hazy or ground glass opacities and small peripheral no dules (Rickman et al., 2002). Acid fast smears of patient sputum are insensitive and should not be used for diagnosis (Khoor et al., 2001). A similar hypersensitivity reaction has been noted in persons exposed to metal working fluid (Hodgson et al., 2001; Wallace et al., 2002). In either case, avoidance of re exposure is key to treatment (Field and Cowie, 2006). Cystic Fibrosis (CF) It has long been known that the lungs of patients suffering from cystic fibrosis are colonized with bacteria. It is believed that the v iscous respiratory secretions, characteristic of CF, contribute to recurring pulmonary infections ( Gilligan, 1991 ). Mycobacteria were first isolated from patients suffering from CF in 1980, but the severity of disease has only been recognized in more rece nt years ( Boxerbaum, 1980; LiPuma, 2010 ). The prevalence of NTMs recovered from the sputum of CF patients was previously reported to be 13% (Olivier et al., 2002). However, determining the exact burden of disease in this population has proven difficult a s overgrowth of sputum


27 samples with other bacteria may lead to an underestimate of the infection rate of these patients with NTMs (Bange and Bottger, 2002). Better treatment of CF has lead to increased longevity largely thanks to better medications, inhal ed formulations improved nutrition, and improved sputum clearance techniques ( Simmonds et al., 2010 ). Ironically, however, studies have indicated that older CF patients (>10 years of age) were more likely to have NTM infections (Field and Cowie, 2006). T hus, there appears to be a correlation between age and risk for NTM disease, and is therefore reasonable to believe that more cases of NTM lung disease in CF patients will be reported over the coming decade s as patients survive longer. The increased age o f CF patients has also led to an increase in other pulmonary pathogens in these patients, including drug resistant Staphylococcus aureus ( Razvi et al., 2009 ). Interestingly, studies have found CF patients were more likely to have NTM infections if they we re co infected with Staphylococcus aureus (Field and Cowie, 2006). This co infected state makes it more difficult to determine the true extent of the damage derived from either disease state, so the contribution of NTMs to respiratory decline in CF patien ts is still an area of debate. Studies have suggested that NTMs produced no effect on clinical lung function tests in CF patients, but HRCT scans of the chest suggest NTM presence is predictive of disease progression ( Griffith, 2003 ). Additionally, CF pa tients whose sputum grows NTMs were more likely to show a progression of their pulmonary parenchymal disease (Field and Cowie, 2006). Therefore, it is recommended that any CF patient with repeated, persistent, infectious symptoms despite traditional antib iotics should be evaluated for a mycobacterial disease (Vaerewijck et al., 2005).


28 Disseminated D isease Having an immune deficiency carries the greatest likelihood for contracting disseminated disease due to NTMs or TB (Howard and Byrd, 2000). Disseminate d NTM infection has been identified in persons with leukemia (especially hairy cell), lymphoma, collagen vascular disease, bone marrow and solid organ transplants, familial immunodeficiences, chronic corticosteroid use, and with advanced AIDS (Weinstein et al., 1981; Zakowski et al., 1982; Horsburgh et al., 1985; Bennett et al., 1986; Newport et al., 1996; Roy and Weisdorf, 1997; Barcat et al., 1998; Nagy and Rubin, 2001; Griffith et al., 2007; Eneh et al., 2010). Of the immunocompromised states, AIDS carr ies the worst prognosis in the event of a disseminated disease due to an NTM, and occurs most commonly when CD4 counts drop below 75 100/mm 3 (Nightingale et al., 1992; Falkinham, 2003). The most common presenting symptoms are quite vague and include fever anorexia, malaise, weight loss, and night sweats. Abdominal pain and diarrhea are not uncommon (Horsburgh 1991; Benson and Ellner 1993; Griffith et al., 2007). Commonly there is also widespread involvement of the reticuloendothelial system with accom panying hepatosplenomegaly, lymphadenopathy, and severe anemia, frequently requiring transfusions (Havlik et al., 1992). The organism burden is often quite high in these individuals and is consistent with persistent bacteremia (Wong et al., 1985; Torriani et al., 1996). Pathology studies indicate involvement of the liver, spleen, bone marrow, and gastrointestinal tract often to levels as high as 10 7 to 10 10 CFU/g, as well as a possible association with nephrocalcinosis of the kidneys and peritoneal inflam mation (Falkoff et al., 1987; van der Reijden et al., 1989; Perazella et al., 1993). Diagnosis is typically confirmed through culture of blood or biopsied tissues and staining of tissues for acid fast organisms within foamy macrophages (Wong et al.,


29 1985; Torriani et al., 1996; Eneh et al., 2010). Ironically, pulmonary symptoms are not believed to occur in these patients (Field and Cowie, 2006). The risk of disseminated NTM in AIDS patients is high in developed countries and low or absent in developing nations (von Reyn et al., 1996; Gopinath 2010). NTMs are isolated from the environment in developing nations and healthy Africans have been shown to have significant reactivity to MAC antigens implying exposure does occur in Africa and other developing n ations (von Reyn et al., 1993). Despite this, disseminated NTM disease is relatively uncommon in developing countries (von Reyn et al., 1996; Gopinath 2010). The low rate of disseminated NTM has been largely attributed to the death from TB of people wit h AIDS before the CD4 count drops low enough to allow for disseminated NTM infection or from a potential mycobacterial immunity conferred by cross protection from prior TB or BCG vaccinations (von Reyn et al., 2002; Field and Cowie, 2006). The high preval ence of TB may also complicate diagnosis of NTM infection, especially in re source limited countries. In the terminal stages of AIDS when the CD4 count falls below 100, nontuberculous mycobacteria induced disease begins to manifest, and NTMs can be isolate d from blood, tissue, sputum, and fecal samples (Falkinham, 2003; Dos Santos et al., 2010). M. avium is isolated most frequently, specifically serotypes 4 and 8 within the United States (Hoffner et al., 1990; Tsang et al., 1992; Falkin g ham, 2003). Compli cating the issue, as many as 25% of persons infected with disseminated MAC within the AIDS population harbor two or more strains simultaneously (von Reyn et al., 1995). This raises the question of whether infection stems from exposure to mixed populations within a single source or from multiple exposures to single bacterial populations. An additional form of MAC has been


30 recognized within HIV infected individuals harboring previously unrecognized or subclinical MAC infection. In these persons, a local in flammatory syndrome involving culture positive lymphadenitis or other granulomatous disease with draining sinuses and negative blood cultures can occur within two months of beginning antiretroviral therapy (HAART), and so is termed immune reconstitution sy ndrome (DeSimone et al., 2000; Aramaki et al., 2010). Disseminated MAC cases have been decreasing in recent years. NTM disease is not reportable within the United States, so true infection rates must be passively deduced (Gopinath 2010). Despite this, trends suggest that cases of disseminated MAC were increasing and outnumbered the annual cases of TB prior to the introduction of effective prophylaxis against disseminated NTM in 1993 (Horsburgh et al., 2001). The peak incidence is believed to have occur red in 1994 when an estimated 37,000 persons were infected with disseminated MAC (Horsburgh et al., 2001). Indeed, disseminated MAC infection used to be one of the most common bacterial opportunistic infection in adults infected with HIV 1 in the develope d world ( Karakousis, et al., 2004). At that time, NTM disease in AIDS was second only to AIDS Wasting Syndrome as the most common cause of death in these patients with MAC being an independent predictor of mortality, even after adjustment for CD4 lymphocy te counts (Covert et al., 1999; Karakousis, et al., 2004 ). During this period, the burden within the American HIV population for NTM infection was as high as 50%, but HAART has reduced this rate in recent years (Horsburgh, 1991; Aberg et al., 1998; Horsbu rgh et al., 2001; CDC, 2002). Cases of disseminated NTM are now considered less common and thought to occur primarily in patients with advanced AIDS not under medical care or in persons non


31 compliant with HAART or MAC prophylaxis (Kovacs and Masur, 2000). Prior to these measures, disseminated MAC infection was associated with a four to five month reduction in survival (Horsburgh et al., 1991; Chin et al., 1994). Prophylactic treatment and treatment of disseminated MAC includes administration of clarithro mycin or azithromycin and ethambutol, as well as HAART therapy to reconstitute the immune system (Havlir et al., 1996; Aberg et al., 1998; Benson et al., 2000; CDC, 2002; Griffith et al., 2007). Treatments must be continued indefinitely in patients with a dvanced AIDS, but may be safely discontinued after 12 months in those persons achieving immune reconstitution, as defined by an increase in CD4 counts to >100/mm 3 for at least six months (Aberg et al., 1998; CDC, 2002; Griffith et al., 2007). Prophylaxis is important as, despite aggressive antibiotic therapy, disseminated NTM disease has reported to have only a 10% survival rate (Howard and Byrd, 2000). Though the dominant source of infection is unknown in many cases, studies have implicated water from ho spitals, patient homes, and recirculating hot water systems as sources of infection, with several identifying the identical isolates from water and patient samples (von Reyn et al., 1994; Aronson et al., 1999; von Reyn et al., 2002). Thus, it is likely th at water may be a potential source of infection in these persons. It is recommended that any water given immunocompromised patients be filtered, and that showering be avoided due to risk of aerosolization of these organisms (Vaerewijck et al., 2005). Immu nology While only a very small percentage of human mycobacterial interactions progress to outright infection, it has been noted that this progression is far more common in the immunocompromised, especially AIDS pat ients (Arasteh et al., 2000). NTMs primar ily


32 enter the body through the bronchial or intestinal mucosa after either inhalation or ingestion. Once inside, the NTMs are taken up into host macrophages via compliment or C3 mediated phagocytosis ( Swarz et al., 1988; Schlesinger et al., 1990; Schlesin ger and Horwitz, 1991; Bermudez et al., 1991). While most bacteria are killed within macrophages, NTMs inhibit phago lysosomal fusion, thereby preventing the oxidative burst (Frehel et al., 1986; Frehel et al., 1991; Crowle et al., 1991; de Chastellier et al., 1993; Sturgill Koszycki et al., 1994). Avoiding normal lytic functions of the macrophage, NTMs are able to reproduce within the phagosomal compartment (Frehel et al., 1991). Eventually the macrophage lyses releasing the bacteria. Whether they are t aken up by non activated or activated macrophages determines whether the bacteria is killed or undergoes a continued cycle of reproduction (Crowle et al., 1991; Sturgill Koszycki et al., 1994). Ultimately, a cell mediated immune response is needed for inf ection control. Severely immunocompromised persons, such as people who have AIDS, cannot mount an effective immune response, so the infection remains uncontrolled ( Nightingale et al., 1992; Falkingham, 2003 ). In the majority of persons, the immune system is able to clear these bacteria, but the subsequent release of potent immunomodulators derived from as allergies, pulmonary viral infections, and irritations of the bowel (Black, 2001; Primm et al., 2004). Mycobacterial infections can also disturb the immune system. Hypersensitivity pneumonitis induced by mycobacterial infections has been shown to cause a strong deregulation of pulmonary immunity, particularly by affectin g either TNF 12, or IFN (Howard and Byrd, 2000; Kitaura et al., 2001; Field and Cowie, 2006). Increased


33 susceptibility to NTMs infection has been associated with mutations in five genes: IFNGR1, IFNGR2, IL12RB1, IL12B, and STAT1 (Vaerewijck et al., 2005). Other reported risk factors of increased susceptibility include: rural residence, living in the Southeastern United States, Black race, birth outside of the United States, history of bronchoscopy, swimming in an indoor pool, 6 or more years of cumulative occupational exposure to soil, consumption of raw or partially cooked fish or shellfish, treatment with granulocyte colony stimulating factor, and owning or working with an aquariu m (von Reyn et al., 1996; Vaerewijck et al., 2005; Reed et al., 2006). Soft tissue/ Cutaneous Manifestations NTMs are a known cause of soft tissue diseases including tenosynovitis, panniculitis, fasciitis, synovitis, osteomyelitis, septic arthritis, meni ngitis, and sarcoidosis (Jacob et al., 1993; Hellinger et al., 1995; Li et al., 1999; Frosch et al., 2000; Weitzul et al., 2000; Arend et al., 2001; Cheung et al., 2010). The most common manifestation within the United States of NTM infection is granuloma (Philpott et al., 1963; Wolinsky, 1979; Littlejohn and Dixon, 1984; Vincenzi et al., 1992; Dobos et al., 1999; Cheung et al., 2010). These lesions occur when environmental mycobacteria gain entry into human skin via scrapes, punctures, or other forms of trauma. Once inside a human host, the NTMs cause a localized infection manifesting as papules, nodules, plaques, ulcers, or panniculi tis like lesions (Streit et al., 2008). These skin lesions occur most commonly on the extremities including elbows, hands, fingers, knees, feet, and toes (Collins et al., 1985). Biopsy and drainage material is usually negative for acid fast bacteria and usually heal spontaneously, though patients often remain positive on tuberculin skin tests long after the lesion has healed (Judson


34 and Feldman, 1974). In rare cases, satellite lesions occur that can ascend up the extremity via lymphatic spread (Wolinksky et al., 1972; Cheung et al., 2010). In the United States and Europe, these cases are usually caused by M. marinum through contact with infected water or infected animals, especially fish (Zeligman, 1972; Aubry et al., 2002; Cheung et al., 2010). M. avium complex, M. kansasii M. terrae, M. malmoense, M. xenopi, M. abscessus, M. chelonae, M. smegmatis, and M. fortuitum complex are examples of other NTM species known to cause cutaneous infections, and have similarly been associated with exposure to water in cluding hot tubs, public baths, and footbaths (Aubuchon et al., 1986; Zenone et al., 1999; Lee et al., 2000; Winthrop et al., 2002; Streit et al., 2008). These cases occur in both fresh and salt water and certain activities, such as aquatic farming and ow ning an aquarium, carry a greater risk of infection (Huminar et al., 1986). Compared with historical rates, it appears that the incidence of such diseases is increasing (Dobos et al., 1999). Worldwide, buru li ulcer caused by M. ulcerans is the most preva lent, but occurs exclusively in tropical locations (George et al., 1999). Buruli Ulcer One of the most common forms of NTM is the buruli ulcer caused by M. ulcerans Located in equatorial regions around the world with a particularly high prevalence in We st and Central Africa, buruli ulcers are a debilitating disease characterized by large necrotic skin ulcers involving massive necrosis of the subcutaneous fat that are often incurable (George et al., 1999). Death is an unusual result of buruli ulcers, but permanent deformities are common (Buntine et al., 2002). Treatment often involves a combination of surgery and multiple antimycobacterial drugs, placing a significant financial burden on infected persons (Drummond, 1998; Asiedu 1998). Buruli ulcer


35 most often infects healthy individuals with no known immunological dysfunction, and is usually acquired from environmental sources, particularly water and soil (George et al., 1999). The incidence of buruli ulcers is increasing in certain parts of the world w ith rates in some African villages reaching levels greater than 22% with reported annual incidences rates higher than that of TB (Amofah et al., 1993; Marston et al., 1995; Ragunathan et al., 2001). Thus, buruli ulcers are an important NTM disease as the i ncidence is increasing, it is expensive to treat, and is most common in regions lacking advanced medical facilities (Asiedu, 1998). M. ulcerans likely evolved from M. marinum. M. ulcerans is closely related to M. marinum the primary cause of fish tank g ranuloma, showing >99.8% similarity in their full 16S rRNA sequences and similarly high levels of sequence conservation between other genes (Stinear et al., 2000). Despite their genetic similarities, they are very distinct phenotypically, including slower growth in M. ulcerans differing host specificity, differing temperature requirements, and differing immunological responses to the two organisms. In M. marinum as with most NTMs, the bacterium replicates within the host macrophages and provokes the for mation of a granuloma, whereas in M. ulcerans histopathology shows a marked absence of a host inflammatory immune response and massive numbers of bacilli are found extracellularly (WHO, 2001). This unusual pathology has been attributed to a peptide, mycol actone, produced by M. ulcerans but not M. marinum (George et al., 1999). This mycolactone causes the characteristic necrosis of the skin and also has immunosuppressive properties (George et al., 1999). M. ulcerans was recently found to contain a large plasmid having all the genes necessary for mycolactone synthesis (Stinear et al., 2004). This has led to the belief


36 that M. ulcerans may be a clone of M. marinum that acquired a plasmid from another organism (Yip et al., 2007). Though the main role of my colactone in M. ulcerans has yet to be determined, it is thought that the molecule may confer fitness for the survival within the salivary glands of aquatic insects (Masollier et al., 2002). If M. ulcerans did truly evolve from M. marinum this would be a n excellent example of a significant human pathogen developing from environmental forebears. Traumatic W ound/ Surgery Contaminated water may lead to mycobacterial skin infections and nosocomial infections. Despite being a recognized problem for decades, the number of reports of pathogenic mycobacterial disease from the use of contaminated devices or invasive procedures has been increasing in recent years (De Groote et al., 2002; Cortesial et al., 2010). This is unsurprising given that some of the highest rates of contamination of drinking water have been reported in hospitals, hemodialysis units, anesthesia units, and dental offices (Carson et al., 1988; Schulze Robbecke et al., 1995; Fujita et al., 2002; Vaerewijck et al., 2005; Langevin et al., 2008). Indeed, the linkage between contaminated hospital waters and mycobacterial infections has been recognized for many years, and it is currently believed that the growth and persistence of these organisms in municipal and hospital water supplies combined with their inherent resistance to disinfectants provides a likely explanation for these cases (Graham et al., 1988; du Moulin et al., 1988; Peters et al., 1995; Wallace et al., 1998; El Sahly et al., 2002; Fujita et al., 2002; Lombardi et al., 2002; Falkingham 2002). Important reservoirs for these bacteria within the hospital setting include: potable water, bedside drinking water carafes, water fountains, sinks, faucets aerators, showers, immersion tubs, toilets, dialysis water, anesthesia breathing circuits, ice and ice machines, water baths, flower


37 vases, eyewash stations, dental unit stations, biofilms on equipment, and contaminated solutions and disinfectants (Carson et al., 1978; Safranek et al., 1987; Vaerewijck et al., 2005; Langevin et al., 2008; Corte sial et al., 2010). Despite this known risk, epidemiological tracking has proven problematic. There are 3 main factors that complicate investigation of waterborne transmission of NTMs. First, though some outbreaks do occur, infections are typically spora dic. Secondly, there are many potential sources of exposure other than water. Thirdly, the typing schemes routinely used are not sufficiently discriminating to confidently identify whether an environmental isolate is the same as one derived from a patien t (Pedley et al., 2004). Most of these cases can be traced back to contaminated devices and solutions or water used for washing instruments. M. abscessus is one of the most commonly reported causes of post surgical mycobacterial infection, especially afte r plastic surgery, but M. fortuitum, MAC M. gordonae, and M. xenopi have been implicated in skin infections following iatrogenic procedures such as liposuction, facial blepharoplasty, augmentation mammmoplasty, and other cosmetic procedures (Wolinksky, 19 92; Wallace et al., 1998; Murillo et al., 2000; Phillips and von Reyn, 2001; Vaerewijck et al., 2005). As with most mycobacterial infections, the presentation is often indolent with long incubation times, thus, the original exposure may have been long bef ore the clinical presentation which complicat es diagnosis and epidemiological studies (Howard and Byrd, 2000; Griffith et al., 2007). Clinically, most cases present with localized abscesses often accompanie d by purulent drainage, fistula formation, fever and cellulitis (Wallace et al., 1998; Murillo et al., 2000). Once suspected, these organisms are typically readily culturable, but can be very difficult to eradicate (Wallace et al.,


38 1998; Phillips and von Reyn, 2001). In addition to considering the tr eatment of individual patients in these situations, care must be taken to determine if these cases represent real or pseudo outbreaks from a shared contaminated device or solution (Phillips and von Reyn, 2001). Examples of contaminated equipment include e ndoscopes, bronchoscopes, injection needles, artificial breasts, vascular devices, pacemakers, and orthopedic devices (Robicsek et al., 1988; CDC, 1991; Gubler et al., 1992; Sniadack et al., 1993; Maloney et al., 1994; Griffiths et al., 1997; Wallace et al ., 1998; Verghese et al., 1998; Galil et al., 1999; Katz et al., 2000; Murillo et al., 2000; Astagneau et al., 2001; Kressel and Kidd, 2001). The contamination of these devices is often attributed to inadequate cleaning and disinfecting or to the water us ed in the process, and it is not uncommon for equipment such as automated bronchoscope disinfecting machines, to become heavily contaminated (Sniadack et al., 1993; Wallace et al., 1998). Due to the nature of these outbreaks, clinicians, nurses, laborator y workers and infection control and public health professionals often play important roles in the evaluation of individual cases and the determination of cause. Chronic Bowel Disease M. avium subsp. paratuberculosis (MAP) has been suggested as a cause o f Crohn's disease (CD) in humans, and has been a subject of much investigation over the last few decades. MAP was first identified at the Veterinary Pathology Institute in Dresden in 1895 as the causative organism in a case of chronic inflammation of the intestinal tract of a cow (Johne and Frothingham, 1895). This disease became known as decreased milk yield, and diarrhea (Doyle, 1956; Buergelt et al., 1978; Riemann an d Abbas, 1983; Chiodini et al., 1984 b ; Cocito et al., 1994; Clarke, 1997; Beth Harris and


39 Barletta, 2001; Manning and Collins, 2001). Though originally identified in cows, JD can affect ruminants, deer, bison, elk, dogs, pigs, horses, chickens, rabbits, b irds, foxes, insects, worms, and primates and is invariably fatal (Greig et al., 1999; Buergelt et al., 2000; Ferroglio et al., 2000; Nebbia et al., 2000; Pavlik et al., 2000; Beard et al., 2001; Fischer et al., 2001; Fischer et al., 2003). Internally, MA P causes chronic inflammation of the intestinal tract, specifically, the terminal ileum and colon with segmental lesions and rectal involvement. The gut wall becomes thickened, mucosal surfaces swell producing ulcers, and the regional mesenteric lymph nod es become enlarged (Buergelt et al., 1978; Cocito et al., 1994; Manning and Collins, 2001). In vivo, MAP falls into two categories: a pluribacillary form with abundant acid fast bacilli within intestinal macrophages (similar to lepromatous leprosy) and a paucimicrobial form with no visible acid fast bacteria but with chronic granulomatous inflammation (similar to tuberculoid leprosy) (Hermon Taylor, 1998). This paucimicrobial form of JD closely resembles CD in humans leading many to speculate MAP as the c ause of CD (Hermon Taylor, 1998; Timms et al., 2011). Given the similarity in disease state between JD of animals and CD in humans, Lammerding, 2001). There has been some microbio logical and clinical data suggesting M. avium subsp. paratuberculosis (MAP) as the cause of CD (Chiodini et al., 1984 a ; Chiodini et al., 1986; Chiodini et al., 1989; Hermon Taylor et al., 1998). T he main characteristics of chronic inflammatory bowel syndr ome seem to fit well with the notion of mycobacterial involvement. O ral infection of M. avium into immunocompromised mice results in a strong inflammatory response and necrosis of


40 the intestinal mucosa, similar to chronic bowel disease, and M. genavense i nfections in HIV patients often result in abdominal wall thickening, lymphadenopathy, and ulceration, all of which are symptoms of chronic inflammatory bowel disease (Kim et al., 1998; Monill et al. 2001). Proving these linkages, however, has proven to b e more difficult than expected. For starters, CD appears to have a genetic component and so causation is likely to be multifactorial (Orholm et al., 1991; Yang et al., 1993; Peeters et al., 1996; Koets et al., 2000; Orholm et al., 2000; Brest et al., 2011 ). Secondly, MAP grows slowly even for mycobacteria, requiring at least 16 weeks in culture before visible colonies can be noted (Zhang and Zhang, 2011). Further, MAP requires the supplementation of exogenous mycobactin, an iron transport protein, for in vitro growth (Merkal and McCullough, 1982; Zhang and Zhang, 2011). Given the slow growth and unique media requirements, it is easy to see how MAP could fail to be grown in many cases. Confounding the issue even further, the culture conditions used can d ramatically change phenotype and resistance of MAP isolates (Sung and Collins, 2003). MAP, for example, can switch between the traditional acid fast positive cells to a tough, acid fast negative form that is invisible by ordinary light microscopy (Van Kru ningen et al., 1986; Hermon Taylor, 1998; Thomas et al., 1998; Pedley et al., 2004). MAP is also capable of switching between activated cells and latent cells, which differ in regards to resistance to lysis and immunological interactions (Hermon Taylor et al., 2000; Naser et al., 2000; Odumeru et al., 2001). For all these reasons, MAP is a difficult organism to isolate, and many MAP strains cannot be grown at all (Scheibl and Gerlach, 1997; Pillai et al., 2001). Therefore, conventional laboratory culture is not a consistently reliable method of


41 detection for MAP which is problematic as fecal culture remains the gold standard for detection despite the development of new ELISA and IFN (Eamens et al., 2000; Kalis et al., 2000; Whit tington et al., 2000). People may be exposed to MAP by food and contaminated water. MAP has been isolated in high numbers excreted in large numbers in the feces of cattle and other animals and these are pathways assoc iated with high risk of transmission to humans (Doyle, 1954; Streeter et al., 1995; Millar et al., 1996; Hermon Taylor et al., 2000 ; Gao et al., 2002; Corti and Stephan, 2002; Moghadam et al., 2010). MAP organisms introduced through contamination from run off of heavily grazed pastures are believed to exist in both planktonic form and within protozoa. This growth within protozoal species such as, Acanthamoeba castellanii is likely the explanation for the ability of MAP organisms to survive in the environm ent for months to years (Barker and Brown, 1994; Falkingham, 1996; Ford, 1999; Hermon Taylor et al., 2000). Also, MAP organisms grown in protozoa have an increased capacity to infect human colonic cells, as well as an enhanced virulence in mice (Cirillo e t al., 1997). Thus, cycling through unicellular organisms may increase the virulence of these organisms once in the environment, and any MAP organisms surviving removal of suspended solids in water treatment are not likely to be killed by chlorination (Ta ylor et al., 2000; Whan et al., 2001). Indeed, conspicuous clusters of CD have been noted in areas with exposure to waters whose watersheds included heavily grazed pastures with significant fecal runoff (Mayberry and Hitchens, 1978; Allan et al., 1986; He rmon Taylor, 1993; Van Kruiningen and Freda, 2001; Pierce, 2009). Given the wide range of domestic and wild animal reservoirs for MAP and the ability of these organisms to


42 survive for long periods in the environment, it is easy to see how the excretion of such high numbers could translate into a n infection risk for humans (Pierce, 2009). Interestingly, geographical regions with acidic soils rich in humic and fulvic acids, such as those in Florida, have been suggested to favor accumulation of MAP in the en vironment (Kopecky, 1977; Kazda et al., 1990; Johnson Ifearulundu and Kaneene, 1997; Iivanainen et al., 1999; Kirschner et al., 1999; Reviriego et al., 2000). Cervical L ymphadenitis NTMs are a major cause of cervical lymphadenitis in children. In develop ing nations M. tuberculosis is the most common cause of sub acute and chronic lymphadenitis. In North America, NTMs are the more common cause with a cervical presentation being most common followed by inguinal and axillary adenitis (Wallace et al., 199 0; Inderlied, 1993; Chesney, 2002; Griffith et al., 2007). The linkage between NTMs and cervical lymphadenitis has been known since 1957 (Prissick et al., 1957). Since that time, many mycobacterial species have been implicated with M. avium intracellular e M. scrofulaceum and M. kansasii most commonly reported; in recent years, however, other mycobacterial species have emerged, including M. malmoense (McCrossin and Mailman, 2006). Cervical lymphadenitis is purported to be a result of exposure to environ mental mycobacteria from drinking water (Primm et al 2004). The age range for the majority of cases is between 6 months and 2 years with a mean age of 3.4 years, a male to female ratio of 1:1.5, and often coincides with the eruption of teeth and the pro ximity of the home to water (Wolinsky, 1979; Wolinsky, 1995; McCrossin and Mailman, 2006; Thegerstrom et al., 2008). Infection is generally limited to cervical and mandibular lymph nodes and accompanied by gradual onset of painless, unilateral cervicofaci al lymphadenopathy often lacking fever and is unresponsive to anti


43 staphylococcal antibiotics. If left untreated, the nodes will gradually enlarge producing a skin discoloration followed closely with fistula formation and external drainage (McCrossin and Mailman, 2006). Surgical removal of the infected lymph nodes has the best prognosis for cure, as antituberculous drugs and most antibiotics are ineffective (Schaad et al., 1979; Starke et al., 1995; Primm et al., 2004; Griffith et al., 2007). The most im portant issue for diagnosis is the differentiation between NTM and TB induced disease. Skin testing for TB (PPD) often show s p ositive results in both cases, so it does not differentiate between tuberculous disease and MAC cervical adenitis (Chesney, 2002) The gold standard of diagnosis remains isolation in culture which carries only a 50% sensitivity and requires weeks of culture (American Thoracic Society Statement, 1997; Pedley et al., 2004; Griffith et al., 2007). Thus, the mean time to correct diagn osis is often longer than 3 months (15 weeks), and the low level of suspicion for NTM lymphadentitis often causes diagnostic delays, multiple bouts of antibiotics, and delayed referral for surgery (McCrossin and Mailman, 2006). Moreover, it has been noted that the incidence of cervical lymphadenitis in children caused by environmental mycobacteria has increased in western countries, especially since the cessation of the BCG vaccination, leading many to wonder if vaccination was protective against this as w ell (Katila et al., 1987; Romanus et al., 1995; Thegerstrom et al., 2008). Wildlife and Veterinary Diseases NTMs have the ability to infect mammals, birds, fish, and humans, and have evolved mechanisms by which they can invade and grow within host cells. In addition to causing Johne's disease, NTMs have been isolated from a wide range of organisms including: aquatic insects, nematodes, earthworms, intestinal helminthes, water buffalo, pigs, deer, horses, cats, dogs, armadillos, cynomolgus and rhesus macaq ues,


44 marsupials, ferrets, chickens, white carneaux pigeons, emus, rheas, flamingos, and various fish species (Pond and Rush, 1981; Mann et al., 1982; Fleischman et al., 1982; Morse and Hird, 1984; Bellinger and Bullock, 1988; Goodwin et al., 1988; Odiawo a nd Mukurira, 1988; Robinson et al., 1989; Shackelford and Reed, 1989; Sills et al., 1990; Dhople et al., 1992; Schoon et al., 1993; Shane et al., 1993; Sanford et al., 1994; Fawcett et al., 1995; Miller et al., 1995; Kaufman et al., 1995; Hunter, 1996; Hel ie and Higgins, 1996; Leifsson et al., 1997; Montali et al., 1998; Bollo et al., 1998; Portaels et 2000; Pavlik et al., 2000; Astrofsky et al., 2000; Heckert et al., 2001; Ramasoota et al., 2001; Lloyd et al., 2001; Diniz et al., 2001; Freitas et al., 2001; Whittington et al., 2001; Marsollier et al., 2002; Fischer et al., 2003; Kane et al ., 2007; Stine et al., 2010). Because the number of organisms shed back into th e environment from infected animals can be relatively small, and heavy and widespread colonization of some environments occurs, it remains unclear what role animal/human infection plays in the life cycle of many of NTMs (Pedley et al., 2004). However, NTM s such as M. avium subspecies paratuberculosis difficult to recover from environmental samples, are excreted in large numbers in the feces of infected animals and are likely to be present in water sheds used for drinking water (Mayberry and Hitchens, 1978; Allan et al., 1986; Hermon Taylor, 1993; Van Kruiningen and Freda, 2001). Thus, NTMs may exert a significant economic impact on as potential reservoirs for human disease (Primm et al., 2004).


45 Intracellular Growth Mycobacteria can live intracellularly. Macrophages are important in spread of NTMS within the host. M. avium has also been shown to survive and grow in phagocytic prot ozoa ( Tetrahymena pyriformis ) and amoeba ( Acanthamoeba polyphaga and Acanthamoeba castellanii ). Intracellular habitats provide a safe haven when environmental conditions deteriorate, but this intracellular growth cycle also imparts other advantages and is important for several reasons (Cirillo et al., 1997; Steinert et al., 1998; Miltner and Bermudez, 2000; Skriwan et al., 2002). First, many protozoal species phagocytize and consume bacteria, so surviving phagocytosis is a major advantage to a water borne bacterium. NTMs, such as M. avium, M. intracellulare, and M. scrofulaceum achieve this anti phagocytic behavior by inhibiting lysosomal fusion within the amoeba (Primm et al., 2004; Vaerewijck et al., 2005). Avoiding production of the phagolysosome also imparts a unique virulence to these bacteria. When compared with culture grown M. avium amoeba grown M. avium have been demonstrated to be more invasive towards human epithelial cells and macrophages, as well as mouse intestinal cells, thereby demonstrat ing increased virulence after living intracellularly (Cirrillo et al., 1997). Moreover, growth rates for M. avium, M. intracellulare, and M. scrofulaceum were shown to be four to forty fold increased when grown within protozoa as compared to free living m ycobacteria, and mycobacteria that are grown intracellularly are more resistant to antibacterial agents than those derived from culture (Miltner and Bermudez, 2000; Stahl et al., 2001). Further, NTMs can survive the encystment process, and may use protozo al encystment as a means to survive starvation and toxic stresses (Steinert et al., 1998; Strahl et al., 2001). It follows then that this parasitic cycle may help explain the opportunistic nature


46 of NTM disease. Situations that allow these protozoal host s to thrive may increase the NTMs in the environment. Such was the case with an epizootic of MAC in flamingos that was found to be coincident with an algal bloom in water (Cirillo et al., 1997). Few studies have examined the risk of these intercellular m ycobacteria to human health or the water supply, but efforts to control biofilm levels in distribution lines would also likely result in lower amoeba and protozoal levels, as these organisms feed on biofilms (Loret and Greub, 2010). In summary, it is beli eved that protozoans may have played a crucial role in the evolution of pathogenicity of mycobacteria and the selection for NTMs that can infect protozoans has most likely resulted in the ability of mycobacteria to become intracellular pathogens in animals as well (Primm et al., 2004). Environmental Distribution Mycobacteria have been isolated from an extraordinarily large, ubiquitous range of habitats. NTMs are widespread in the environment with little evidence of person to person transmission, so it i s assumed that infections are derived from water, food, animals, or the environment (Pedley et al., 2004). The presence of NTMs ha s been reported in such varied environments as deionized sterile water, hot tap water, pools, spas, ice machines, municipal w ater sources, dental equipment, bronchoscopes, anesthesia breathing circuits, metalworking fluid, various animal species, Sphagnum vegetation, peat rich soils, brown water swamps of the Southeastern United States, water and soils with low dissolved oxygen content, and dust (Stine et al., 1987; Kirschner et al., 1992; Dawson et al., 1992; Katila et al., 1995; Langevin et al., 1999; Shelton et al., 1999; Falkingham, 2003; Primm et al., 2004; Vaerewijck et al., 2005; Field and Cowie, 2006; Sood et al., 2007).


47 The ubiquitous nature of NTMs may be due to their ability to utilize a wide array of carbon and energy sources such as hydrocarbons, and humic and fulvic acids which allow s them to survive in environments inhospitable to other organisms. Thus, the appa rent ubiquitous nature of NTMs in water, soil, and other environments is likely due to the ability of mycobacteria to exploit niches unoccupied by other, faster growing organisms (Pedley et al., 2004). NTMs metabolize a broad range of hydrophobic hydrocar bons including paraffin and chlorinated hydrocarbon pollutants, and the importance of these hydrocarbons in mycobacteria is emphasized by the large number of genes involved in lipid catabolism within the genomes of NTMs (Ollar et al., 1990; Rafii et al., 1 994; Primm et al., 2004). While mycobacteria are able to survive in water that is sterile or that contain s only trace amounts of nutrients, drinking water derived from environments rich in humic and fulvic acids have much higher numbers of mycobacteria an d more of these NTMs tend to be in the form of biofilms (Vaerewijck et al., 2005). The growth of NTMs from environmental sources also appears to be stimulated by humic and fulvic acids, and the number of MAC organisms recovered from environmental waterway s was similarly found to correlate with concentrations of humic and fulvic acids (Kirschner et al., 1999). These compounds are further thought to be of significance as they are the princip al organic compounds draining out of two locations whose high mycob acterial levels have been well documented peat rich boreal forests and acidic, brown water swamps, such as those present in Florida (Iivanainen et al., 1997; Kirschner et al., 1999). In addition to h umic and fulvic acids water chemist ry such as oxygen content, temperature, pH, or the presence of inorganic


48 molecules also appears to affect the survival of NTMs (Brooks et al., 1984; Kirschner et al., 1992). Water T here is significant regional variability in the number of reported NTM diseases around the c ountry. Significantly more NTM cases seem to be reported in persons residing in the Southeastern United States (Reed et al., 2006). In fact, the CDC found that over 41% of all reported isolates in the US were from the Southeast ( Dobos et al., 1999). Not surprisingly, M. avium complex organisms can be found in largest numbers in brackish swamps and estuaries of the Southeastern coastal United States (Kirschner et al., 1992; Kirschner et al., 1999). Further, members of the M. avium complex, M. scrofulaceu m, M. fortuitum and M. chelonae, all human pathogens all grow in water, including environmental waters with and without salt and drinking water distribution systems throughout the world (George et al., 1980; Covert et al., 1999; Falkingham et al., 2001). Moreover, exposure to water is the primary route of human infection by M. scrofulaceum and M. marinum (Falkingham, 1996). It is not unreasonable th e n to believe that water may be the main exposure route to all of these NTMs. Numerous situations exist in which the geographic and environmental distributions of humans and mycobacteria overlap leading to ecological impact on the mycobacteria themselves and exposure of humans to these potential pathogens. The most notable overlap is water H umans are ro utinely exposed to environmental mycobacteria through activities such as drinking water, swimming and bathing. Indeed, persons who work in and around water, such as fishery managers, anglers, and commercial fishermen, are at increased risk of mycobacteria l skin lesions (Panek and Bobo, 2006 ) In Sweden, persons living close to water have a higher proportion of positive reactions to NTM


49 sensitins (Thegerstrom et al., 2008). Within the United States, living or working in water damaged buildings or reconstr uction of these buildings is associated with major outbreaks of NTM induced pulmonary disease (Falkingham, 2003). In fact, the risk associated with NTMs as an emerging pathogen in water systems was acknowledged by the U.S. Environmental Protection Agency (EPA) by the placement of M. avium on the contaminate candidate list for possible regulation in drinking water (Torvinen et al., 2007). It naturally follows then that the primary mode of infection of humans with NTMs is via ingestion or aerosolization of water (Primm et al., 2004). Unsurprisingly, an use and consumption as well as diet, is believed to vary exposure levels (Vaerewijck et al., 2005). Consistent with the oral theory, M. avium has been shown to exhibit high bi le salt and acid tolerance, thereby allowing M. avium to pass through the intestinal tract to invade through the apical surface of epithelial cells in the terminal ileum of the human intestine (Bodmer et al., 2000; Bermudez and Sangari, 2000; Sangari et al ., 2000; Sangari et al., 2001). The invasion of human intestinal cells by M. avium is enhanced at 37C, high osmolarity, and low oxygen tension, but appears unaffected by iron limitation or acidic pH (Bermudez et al., 1997). Person to person contact is n ot believed to be a mode of transmission, but inhalation of dusts and soils, inoculation from environmental sources, food, traumatic exposure and tobacco have all been proposed as other source s of human exposure to environmental mycobacteria (Witty et al. 1994; Yajko et al., 1995; Eaton et al., 1995; Falkingham, 1996; Yoder et al., 1999; Argueta et al., 2000; Pedley et al., 2004; Primm et al., 2004; Vaerewijck et al., 2005). Water, however, appears to be the most probable source of infections.


50 Aerosoliz ation of contaminated water may be critical in allowing respiratory exposure to NTMs. Aerosolization occurs as a result of the high hydrophobicity leading to adsorption to rising air bubbles (van Oss et al., 1975; Blanchard and Hoffman, 1978; Weber et al. 1983). Adsorption to bubbles leads to concentration of mycobacteria within droplets and when these bubbles reach the surface, they burst resulting in several droplets 8 10 cm above the water surface (Blanchard and Szydek, 1978). These aerosolized parti cles associated with mycobacteria are within the size range capable of entering the human alveoli, and it is possible that significant numbers of NTMs can be transferred to the air by this mechanism (Falkingham et al., 1990; Pedley et al., 2004). Thus, it is possible aerosolization could provide a source of infection, particularly of the respiratory tract. By the same process of preferential adsorption to rising air, the high hydrophobicity also leads to mycobacteria concentrating at the air / water interfa ce where organic matter is typically concentrated (Blanchard and Hoffman, 1978; Wendt et al., 1980). This positions NTMs in an environment rich in organic matter where there are few competitors, but many opportunities for human interaction (Pedley et al., 2004). Water Quality Environmental parameters appear to have an impact on mycobacterial growth rates with some conditions more ideal than others for optimized NTM growth. A review of the literature suggests parameters such as temperature, pH, dissolv ed oxygen, dissolved organic carbon, zinc, iron, turbidity, and phosphorous may all play a role in optimizing the growth of mycobacteria (Kirschner et al., 1992; Howard and Byrd, 2000; Primm et al., 2004; Vaerewijck et al., 2005; Bland et al., 2005; Hilbor n et al., 2006; Reed et al., 2006; Torvinen et al., 2007; Sood et al., 2007; Langevin et al., 2008). While each


51 of these may contribute to the overall growth optimum, certain parameters such as dissolved organic carbon, salt tolerance, dissolved oxygen, t emperature, and pH, are believed to be more important DOC M. avium and other NTMs can grow in natural waters and municipal sources containing low dissolved organic carbon (DOC) (George et al., 1980; Falkingham et al., 2001). The presence of biodegradabl e organic matter in water is associated with mycobacterial growth (LeChevallier, 2003; van der Kooij 2003). Biodegradable organic carbon is often measured by AOC ( a ssimilable o rganic c arbon ), and AOC levels have been found to range between 20 to 214g/L w ith a median of 100g/L in North American drinking water systems (LeChevallier et al., 1996; Volk and LeChevallier, 2000). Studies of AOC on mycobacterial biofilm formation have indicated that at increasing AOC levels the density of biofilms increase, and more importantly that M. avium biofilms are capable of forming at levels as low as 40g/L (Falkingham et al., 2001; Norton et al., 2004). Further, increases in M. avium levels in drinking water were found to correlate with AOC levels (Falkingham et al. 2001). Thus, it is possible that decreasing the amount of available biodegradable carbon from a water source may decrease the relative number of mycobacterial biofilms, but is not likely to prevent their occurrence. Conversely low DOC may provide a com petitive advantage to NTMs over faster growing bacteria. Salt T olerance Mycobacteria are capable of growth under an array of salinities. While individual species may exhibit their own varying tolerance levels, mycobacteria have been isolated from both fre sh and brackish waters (George et al., 1980). Indeed, faster growth has


52 been reported in waters containing 1% NaCl (brackish) than in fresh water (Gruft et al., 1981; George et al., 1994; Pedley et al., 2004). This ability to grow in brackish waters helps explain the high numbers of NTMs isolated from the tidal waters of large estuaries, like the Gulf of Mexico and the Chesapeake Bay (Gruft et al., 1975; Gentry, 2004; Panek and Bobo, 2006; Kane et al., 2007). Contrarily, despite reaching appreciable numbe rs in brackish waters, mycobacteria do not appear to grow in high salinity situations, such as seawater (3% NaCl) (Falkingham et al., 1980). Thus, it appears that mycobacteria grow best over low to mid range salinity, but every species has its own unique optimum (Gruft et al., 1981). The salinity correlation is not limited to NaCl, however. Studies have suggested that NTMs are capable of shifting from Na+ rich environments, such as estuaries, to K+ rich environments, like intracellular conditions of mac rophages and protozoa, without loss of viability (Amin et al., 2008). Dissolved Oxygen Higher mycobacterial loads are recovered from waters and soils with reduced oxygen levels. Mycobacteria are obligate aerobes requiring oxygen for growth, but paradoxic ally, they also have the ability to survive and metabolize under hypoxia (Berney and Cook, 2010). While NTMs cannot grow anaerobically, they are capable of surviving rapid shifts in anaerobiosis (Pedley et al., 2004). Though surviving such shifts, mycoba cteria experience energetic challenges when placed in hypoxic conditions, and changing the oxygen level can dramatically affect the doubling time for mycobacteria ( Berney and Cook, 2010). The most rapid growth is said to occur between 12% and 21% oxygen, but growth has been reported at levels as low as 2.5% oxygen (Palamino et al., 1998; Pedley et al., 2004). To survive, mycobacteria employ three strategies under hypoxia: high affinity cytochrome oxidases scavenge oxygen,


53 they switch to NAD+/NADH independ ent enzymes, and they upregulate hydrogenases ( Berney and Cook, 2010). In fact, studies have previously found that in some mycobacterial species, specifically M. ulcerans growth stimulation was directly proportional to decreases in oxygen concentrations (Palamino et al., 19 98). Thus, it is not surprising that waters and soils that have low oxygen levels often yield the highest numbers of MAC (Brooks et al., 1984; Kirschner et al., 1992). Temperature Mycobacteria can grow over a wide range of temperatur es and individual species may survive either high heat or freezing conditions (George et al., 1980). Research has demonstrated that more NTMs tend to be isolated in warmer months of the year, and the ideal temperature range appears to be approximately 15 .5 20C though temperature sensitivities vary by species (Torvinen et al., 2007). Further, studies have indicated that temperature is an important factor influencing bacterial growth, and in climates where water temperatures are warm, bacterial growth may be very rapid (LeChevallier, 2003; van der Kooij, 2003). It follows then that the ability to grow at temperatures as high as 45C helps explain NTM presence in hot water systems as well as in coastal brown water swamps of the Southeastern United States w here summer temperatures can surpass 45C (du Moulin et al., 1988; Schulze Robbecke and Buchholtz, 1992; Mijs et al., 2002). Alternatively, the higher NTM numbers isolated from brown water swamps, as with peat rich boreal forests, may be due to the princi pal organic compounds draining from these waters, humic and fulvic acids (Kirschner et al., 1999; Primm et al., 2004; Vaerewijck et al., 2005). Further emphasizing the dynamic nature of these organisms, mycobacteria can survive freezing conditions and may actually have higher


54 counts after freezing, presumably as a result of disaggregation of bacterial c lumps (Iivanainen et al., 1995) pH NTMs have an acidic growth optim um of pH 4.5 to 5.5 (Portaels and Pattyn, 198 2; George and Falkingham, 1986) It is s till unclear, however, whether increased mycobacterial growth under acidic conditions is due to the utilization of acidic compounds in the water or whether these bacteria actually grow better in acidic environments independent of the organic acids Of part icular note, this acidic growth optimum noted for many mycobacteria falls below the pH of commonly used media (Middlebrook 7H9 and 7H10), and may be limiting in the recovery of certain mycobacterial species (Falkingham, 2009). Regardless, mycobacterial gr owth and tolerance within these low pH environments provides another possible explanation for the higher numbers of NTMs reported from soils and waters of peat rich boreal forests and brown water swamps (Kirschner et al., 1992; Iivanainen et al., 1999; De Groote et al., 2006). Interestingly increased survival through water treatment procedures was noted in M. fortuitum samples when the pH was increased from 5.7 to 10.1, suggesting a physiologic change with pH (Farooq et al., 1977). On the other hand myc obacteria are also capable of surviving low pH extremes such as those found in the human stomach (Bodmer et al., 2000). It is likely that mycobacterial growth is not driven by any one of these parameters alone, but by a unique interplay between them all Brown water swamps of southeastern US, such as those in Florida, have four of the major growth optim a demonstrating how difficult it can be to tease out which, if any, parameter driv es the numbers to higher levels in these places. Regardless of cause, t hese higher numbers are concerning


55 because these waters are used as sources for drinking water, and present a risk of introducing NTMs into the municipal water system (Kirschner et al., 1992; Iivanainen et esistance to disinfectants, once allowed to establish, NTMs may grow and persist in drinking water systems (Falkingham et al., 2000; Taylor et al., 2000). Drinking Water Efforts to control mycobacteria have proven difficult. The primary focus of public health efforts to control mycobacteria has been directed toward disease treatment rather than prevention (Saleeb and Olivier, 2010). One area of possible intervention is treatment of drinking water. M ultiple studies demonstrat e the health hazard of NTM exposure via pools, spas, whirlpools, footbaths, showers, and aquariums (Aubuchon et al., 1986; Embil et al., 1997; Kahana et al., 1997; Zenone et al., 1999; Lee et al., 2000; Khoor et al., 2001; Winthrop et al., 2002; Angenent et al., 2005; Streit et al, 2008; Feazel et al., 2009; Cheung et al., 2010). These exposures most commonly result in skin and soft tissue disease, but pulmonary disease has been linked to inhalation of contaminated aerosols in many of these settings (Collins et al., 1984; Embril et al., 1997; Shelton et al., 1999; Griffith et al., 2007; Feazel et al., 2009; Cheung et al., 2010). Additionally, nosocomial infections have also been reported from contaminated tap water and de ionized water used in procedures or to clean equipment for pr ocedures (Stine et al., 1987; Graham et al., 1988; Falkingham, 2002; De Groote et al., 2002; Cortesial et al., 2010). Thus, there is an increasing body of work linking contaminated water sources and NTM disease. Given this trend, it is increasingly more important to understand and control for these infections.


56 Various methods have been proposed for the control of NTMs within drinking water systems. Current water treatment strategies are unlikely to provide adequate protection due to the high level of re sistance of NTMs to disinfectants and their ability to grow as biofilms within distribution lines (Hall Stoodley et al., 1999; Taylor et al., 2000; Falkingham et al., 2001; Le Dantec et al., 2002; Steed and Falkingham, 2006; Falkingham, 2009). Previously, it was shown that some NTMs, such as M. kansasii could colonize cold water distribution systems, whereas M. xenopi and M. avium are more commonly associated from hot water systems (du Moulin et al., 1988; Falkingham, 2002; Pedley et al., 2004). Further, MAC organisms have been recovered from drinking water systems before and after treatment, from distribution lines, and from raw source waters (du Moulin et al., 1988; von Reyn et al., 1993; Glover et al., 1994; Peters et al., 1995; Covert et al., 1999; Ri stola et al., 1999; Falkingham et al., 2001). One MAC clone was isolated repeatedly from a water distribution system over an 18 month study, implying that MAC may not be a contaminant, but a normal inhabitant of drinking water systems (von Reyn et al., 19 94). Indeed, NTM numbers were found to be higher within the distribution system than immediately pre or post treatment, suggesting that NTMs are replicating within such systems (du Moulin et al., 1988; Falkingham et al., 2001). Mycobacterial growth with in these systems is believed to be primarily in the form of biofilms along the length of distribution lines, and the number of such mycobacteria isolated from drinking water can be very high, up to 700,000 CFU /L (Falkingham et al., 2001). Given the length of water pipes in an average distribution system can easily be hundreds even thousands of miles, the potential risk of human exposure is immense (Falkingham et al., 2001).


57 Mycobacterial growth in municipal systems is attributed to environmental factors and the inherent resistances of mycobacteria. Municipal water contamination takes place in three phases. First, NTMs derived from source waters must survive the treatment process. Secondly, NTMs must re grow from relatively low numbers. Thirdly, these NTMs must grow within the water distribution pipelines typically in the form of biofilms, thereby re contaminating the treated water (Pedley et al., 2004). The treatment of water does not entirely eliminate mycobacteria from municipal waters (Falkingham e t al., 2001). Most microbes are removed at treatment plants by two princip al mechanisms physical removal via coagulation, sedimentation or filtration and chemical inactivation via disinfectants (LeChevallier and Au, 2003; Dash et al., 2010; Falkingham, 2 010). The hydrophobic nature of the mycobacterial cell wall promotes attachment to surfaces such as suspended particulate material, thereby aiding in the removal of mycobacteria via physical means (Falkingham et al., 2001; Mazumder et al., 2010). The use of coagulants, however, can destabilize NTM adherence to these particles by neutralizing or reducing the surface electrical charges, thereby releasing the mycobacteria into the water or into a flocculent. Fortunately, flocculated particles often have suf ficient settling velocities to allow for sedimentation, but not all mycobacteria are collected through this process (Harrington et al., 2001; Bell et al., 2002; Bagga et al., 2008; Li et al., 2010). S ignificant reduction of mycobacteria after water filtra tion has been demonstrated but mycobacteria were not completely removed and the filter materials themselves were implicated as potential sources of NTM re contamination of the water distribution systems post filtration (Le Dantec et al., 2002; LeChevallie r and Au, 2003; Falkingham, 2010).


58 The second form of microbial control, inactivation through the use of disinfectants, can also be troublesome in mycobacteria which are among the most resistant microbes (Jacangelo et al., 2002). I ncreased resistance to disinfectants within strains has previously been reported in NTMs derived from low nutrient sources, such as tap water or diluted media, as compared with rich laboratory media (LeChevallier et al., 1988; Taylor et al., 2000; Le Dantec et al., 2002; Steed and Falkingham, 2006). Additionally, clumping, a natural mycobacterial property, imparts strain variability in resistance largely by decreasing the surface area and access to porins (Woelk et al., 2003; Danilchanka et al., 2008; Steinhauer et al., 2010). Given their inherent resistance to disinfectants, it is easy to see how many NTMs would be able to survive water treatment procedures (Taylor et al., 2000). The number of mycobacteria immediately post treatment, however, is believed to be low, suggesting the occurrence of re growth within distribution systems (Feazel et al., 2009). Tap water is known to be a low nutrient system, and for most microbes this creates an inhospitable environment which prevents re growth (Taylor et al., 2000; Radomski et al., 2010; Lautenschlager et al., 2010). Mycobacteria, however, are capable of growing in low nutrient environments by utilizing trace levels of minerals and organic carbon (van Ingen et al., 2010; Radomski et al., 2010; Lautenschlager et al., 2010). Indeed, stored distilled water, the epitome of a low nutrient source, has been demonstrated to harbor NTMs at levels as high as 10 5 to 10 6 mycobacterial cells/mL (Carson et al., 1978; Falkingham et al., 2001; LeChevallier, 2003). Further, studies involving eight water distribution systems indicated that M. avium and M. intracellulare (both MAC species) were frequently isolated from biofilms within municipal samples


59 (Falkingham et al., 2001; LeChevallier et al., 2001; Konstantinos et al., 2010). This finding impl ies that NTMs, even potentially pathogenic species, are regular inhabitants of water distribution systems, and are not likely the result of experimentally derived contamination (Falkingham et al., 2001; Thompson et al., 2008; Konstantinos et al., 2010). T he human activity of treating potable water with chlorine or other disinfectants, such as ozone, has led to selection for environmental mycobacteria by providing a unique ecological niche. For example, MAC, like many NTMs, are relatively resistant to chlo rine, monochloramine, chlorine dioxide, and ozone (Taylor et al., 2000). In the absence of disinfection, M. avium cannot compete effectively for limited nutrients, but disinfection kills competitors permitting growth of M. avium on the available nutrient s (Falkingham et al., 2001). This phenomenon is most likely responsible for the growth of MAC within municipally distributed waters, as well as hot tubs, spas, and showerheads (Embil et al., 1997; Falkingham et al., 2001; Feazel et al., 2009). Moreover, different mycobacteria have differing susceptibility to chlorine and other chemical disinfectants which may lead to human derived shifts in which mycobacteria species are in greatest abundance in water and thereby alter the risk of human exposure to these. For example, before 1970, the majority of cases of cervical lymphadenitis in children were due to M. scrofulaceum which is fairly chlorine sensitive (Wolinsky, 1979). Since 1975, however, M. avium has predominated (Colville, 1993; Wolinsky, 1995). The change is believed to be due to the Clean Water Act of the United States that increased chlorination rates of waters beginning in 1978 (Primm et al., 2004). Similar trends were also noted in England and Australia following changes in their water treatmen t procedures (Colville, 1993; Pedley et al., 2004). In short, the implementation of


60 improved methods for disinfection of drinking water combined with mycobacterial resistance to disinfectants and their presence in the source waters led to selection for MA C and other mycobacteria within distribution systems. Of the drinking water sources analyzed thus far, higher mycobacterial numbers were encountered from systems using surface water and applying ozonation as an intermediate treatment or post treatment than those using non ozonated surface waters, ground water, or mixed water (Vaerewijck et al., 2005). Once through the treatment system, the re growth of NTMs in municipal water systems is believed to be influenced by the concentration of biodegradable organ ic matter, sediment accumulation/ turbidity, microbially available phosphorous and nutrients, concentration of free residual disinfectants, residence time, microbial interactions, pH, temperature, diameter of the pipes, hydraulics, and the characteristics (composition, porosity, and roughness) of the pipes themselves (Thofern et al., 1987; LeChevallier et al., 1993; Vaerewijck et al., 2005). In general, it is accepted that old, corroded pipes containing dead ends and spaces favor mycobacterial growth, as d oes having brass, bronze, iron or galvanized pipes as compared with PVC or copper surfaces, but all these composites yield significantly lower growth than hot water silicon tubing (Schulze Robbecke and Fischeder, 1989; Falkingham et al., 2001; LeChevallier et al., 2001; Vaerewijck et al., 2005). Pipelines may also favor the formation of biofilms due to their hydrophobic character e nhancing bacterial adherence. NTMs have been known to form biofilms for decades (Schulze Robbecke and Fischeder, 1989; Iivanai nen et al., 19 99; Falkingham et al., 2001). The intermittent use of many of these lines leads to stagnation of an entire water column for extended periods of the day which allows for


61 undisturbed bacterial proliferation and potential aerosolization when u sed (Vaerewijck et al., 2005). This makes it possible for high numbers of NTMs to be swallowed, inhaled, or inoculated into wounds which in turn leaves potential for colonization, infection, and immunization (Vaerewijck et al., 2005). As such, the presen ce of MAC in biofilms helps to explain how groundwater derived drinking water systems could test negative for MAC in their source waters, but the distribution lines themselves could test positive for MAC (Falkingham et al., 2001). If one considers the siz e of pipes used for distributing drinking water and the length and number of pipes within the system, the contribution of these biofilms to the microbial flora of drinking water could be substantial (Falkingham et al., 2001; Pedley et al., 2004). More imp ortantly, the presence of NTMs in biofilms represents not only a mechanism for the persistence and growth of mycobacteria within these tubes, but also a reservoir for these organisms (Schelonka et al., 1994). Thus, biofilms associated with piping, such as those in showers, catheters, etc, serve as a potential mechanism for direct human exposure to NTMs. Recontamination of the distribution system can occur via cross connections, backflows, and intrusion events (Ford, 1999; Craun and Calderon, 2001; EPA, 20 02; Sadiq et al., 2003). M ost recognized microbial outbreaks resulting from such recontamination events involve acute gastrointestinal disorders (Swerdlow et al., 1992; Semenza et al., 1998; Mermin et al., 1999; Yassin et al., 2006; Reynolds et al., 2008; Colford et al., 2009). Thus, slowly developing infections, such as those caused by NTMs, would not be easily identified, and so little is known about the risk these pose ( Hoffman et al., 2009 ). Increasingly people are becoming aware of the opportunities for re introduction of microbes into the system, especially through transient negative


62 pressure events (Karim and LeChevallier, 2005; Teunis et al., 2010; Besner et al., 2011 ). These occur as the result of sudden changes in water velocity, usually as the result of main breaks, fire flows, or pump shutdowns, which allow contaminated water and soil to enter the distribution system through cracks, seals, or pipe leaks (LeChevallier et al., 2003; Karim et al., 2003; Karim and LeChevallier, 2005; Teunis et al. 2010; Besner et al., 2011 ). While no studies have examined NTMs specifically in these situations, fecal coliforms and virus introductions are well documented, as is the introduction of organic material, which would promote NTM growth (Kirschner et al., 1992; Iivanainen et al., 1997; Karim et al., 2003; LeChevallier et al., 2003; Gullick et al., 2005; Teunis et al., 2010 ). When soil or water enter the pipe lines, such as during the repair of main breaks, the traditional decontamination step in these situ ations, chlorine swabs, likely do little to inactivate any NTMs that may have been introduced (Taylor et al., 2000; Teunis et al., 2010 ). High velocity flushing is likely to remove any introduced sediment from the system, but carries the added risk of bio film shearing, thereby resulting in a net increase of NTMs within the water column itself (Geldreich and LeChevallier, 1999; Lehtola et al., 2006 ). While this is not believed to be the so urce of free mycobacteria, the current study propose s this as a pote ntial means of introducing mycobacteria into distribution systems. I t is likely that NTMs could be introduced into water distribution systems in this manner, but given the dilutional effect of the water, the relevance of this is more likely as an opportun ity to seed biofilms already existing within the system rather than posing a direct public health concern for single inoculums. Regardless of source, controlling the growth of NTMs within distribution systems is


63 believed to be necessary to ensure the safe ty of municipally distributed wat ers (van Ingen et al., 2010). In summary, efforts to control mycobacteria in water distribution systems have proven difficult. Current water treatment strategies are unlikely to provide adequate protection due to the high level of resistance of NTMs to disinfectants and their ability to grow as biofilms within distribution lines (Hall Stoodley et al., 1999; Taylor et al., 2000; Falkingham et al., 2001; Le Dantec et al., 2002; Steed and Falkingham, 2006; Falkingham, 2009). Source minimization of NTMs is difficult given the ubiquitous nature and variety of sources for contamination (EPA, 2009; Saleeb and Olivier, 2010). Thus, new strategies must be developed to control the risk to the water supply. One suggested strategy t o reduce MAC and other NTMs from water distribution systems is to reduce the particulates (turbidity) in raw and treated waters (Falkingham et al., 2001). Mycobacteria are known to aggregate on particulate matter and turbidity rates of 2 NTU or greater ha ve been demonstrated to enhance the detection rate of MAC from raw water, thereby indicating the concentrations of NTMs, notably MAC, are significantly associated with these higher turbidity levels (Falkingham et al., 2001). Therefore, filtration could be used to reduce turbidity, and has previously been shown to minimize some NTM related pseudo outbreaks in hospitals (Stine et al., 1987; Graham et al., 1988). As discussed, however, MAC and other mycobacteria can grow to high numbers on filters turning th e filters into sources of NTM contamination (Ridgeway et al., 1984; Rodgers et al., 1999; Falkingham, 2009; Falkingham, 2010). Thus, any filters used must be sampled and replaced often (< 3 weeks) (Falkingham, 2009). If filters are to be used, it has bee n proposed that the filters be coated in a hydrophobic material, such as


64 paraffin, to help selectively remove NTMs (Falkingham, 2009). Based on the hydrophobicity of NTMs, it is believed NTMs would aggregate on a hydrophobic surface, and indeed previous w ork demonstrated that almost all (>99.9%) NTMs were removed through the use of one hydrophobic substance, hexadecane (Stormer and Falkingham, 1989). Hydrophobic coatings, however, may reduce the number of non mycobacterial species adhering to the filters (Falkingham, 2009). Other approaches could involve the identification of novel disinfectants active against mycobacteria or the identification of factors contributing to disinfectant resistance. Disinfection, however, would likely kill off most other org anisms thereby selecting for any NTMs that survive, thereby allowing them to flourish in a niche lacking competitors (Falkingham, 2009). Alternatively, short wave length ultraviolet irradiation (UVC) may be an option. Mycobacteria, like most bacteria, ar e susceptible to UVC, and UV irradiation of aq uarium tanks has previously been demonstrated to effectively reduce the numbers of NTMs (Collins, 1971; David et al., 1971; David, 1973; McCarthy and Schaefer, 1974; Agbalika et al., 1984). Thus, UVC may be a means of reducing the numbers of waterborne NTMs from drinking water systems and plumbing, but unfortunately, UV irradiation is also mutagenic, risking the selection for of resistant mutants ( Konickova Radochova and Malek, 1968 ; Falkingham et al., 2009). Another option is the use of copper silver ions as an anti mycobacterialcidal agent. Systems generating copper silver ions are already in place in some hospitals as a means of reducing Legionella and fortunately, NTMs, such as M. avium have previously b een demonstrated to be susceptible to these ions, although at higher levels than those required for Legionella (Liu et al., 1998; Lin et al., 1998; Kusnetsov et al., 2001; Wolschendorfa, et al., 2011 ). The utility of these ions, however,


65 has not been expl ored for NTMs. For recreational waters, it has been suggested that careful maintenance and cleaning as per manufactures instructions be strictly adhered to, as well as periodic shock treatments or daily superheating of water to over 70C to control for NT Ms, and immunocompromised persons and those with scratches and scrapes should be advised to avoid swimming pools, hot tubs, and the like (Embil et al., 1997; Freije 2000; WHO, 2000). Geographical Mapping With the number of cases of NTM related disease increasing every year, the distribution and epidemiology of NTM disease is of critical importance. While NTM disease affects both humans and animals, its ecology is complex and its distribution remains poorly understood (Pedley et al., 2004; Vaerewijck e t al., 2005; Winthrop 2010). A number of studies have evaluated the physiological niche of these organisms within the environment, but few studies have addressed the geographical distribution of infections or the distribution of environmental parameters t hat promote mycobacterial growth (Edwards et al, 1969; von Reyn et al., 2001; Reed et al., 2006; Sood et al., 2007; Langevin et al., 2008; Winthrop, 2010). In order to investigate the geographical distribution of NTMs and any areas where persons may be at an increased risk, studies focusing on the relationships between the biological requirements of NTMs themselves, the ecological conditions that support their survival and growth, and the areas where these overlap are needed. Understanding these fields is crucial to developing or implementing a disease control program (Blackburn, 2010). Determining the spatial distribution of NTM disease requires spatially explicit predictive models, as well as available data on the known occurrence of disease (Blackburn, 2010). For the current study


66 for Health Care Administration (AHCA) database and spatial models and analyses were produced using Geographic Information Systems (GIS). GIS is a f ast growing field in international research, particularly research focusing on epidemiology, ecology, or disease distribution (Clarke et al., 1996; Rogers, 2006; Blackburn et al., 2007; Blackburn, 2010). GIS entails a combination of computer software, com puter hardware, and databases for storing, editing, visualizing, and analyzing spatial data (Curtis et al., 2007). The strength of a GIS is the ability to establish relationships between data sets and analyze them spatially (Blackburn, 2010). Disease dis tributions can easily be reviewed in a GIS, as associations intrinsically exist between the locations of disease occurrences and other factors, such as ecologies promoting long term surv ival, environmental reservoirs, vectors that transmit the disease or at risk populations (Smith et al., 2000; Rogers, 2006; Eisen et al., 2006; Blackburn, 2010). Within a GIS, dissimilar data sets are linked through relational databases to produce dynamic maps portraying spatial associations (Blackburn, 2010). Stated simp ly, GIS evaluates data in space through integration of databases and map visualizations. Visualizing data in the form of maps can be considered the first step in determining spatial patterns (Anselin, 2005). While these maps contain no statistical examin ation, they are informative for localizing disease outbreaks. The second step in the assessment process is the use of spatial autocorrelation techniques to identify statistically significant patterns within the data sets (Anselin, 2005). These statistics are often done through local indicators of spatial autocorrelation (LISA) to determine whether statistically significant spatial patterns exist within the distribution of the data (Anselin, 1995). Places where more occurrences happen than would be expect ed by


67 random chance alone are defined as hot spots, and similarly, areas with significantly fewer occurrences than would be expected by random chance are called cold spots (Getis and Ord, 1992; Anselin, 1995). These tests involve iterative algorithms exam ining the association between the occurrence of disease and neighboring rates (Anselin, 1995 ; Anselin, 2005). For th e current study, neighbors were defined as those polygons sharing a border (rook matrix ) (Anselin, 2005). Final Thoughts NTMs, such as M avium have historically been isolated in the highest numbers in the s outhe a stern US (Falkingham, 1996; Primm et al., 2004), and significantly more NTM infections, approximately 41% of the US total, were reported from persons residing in that region (Dob os et al., 1999; Reed et al., 2006) In fact, approximately 15% of pulmonary mycobacterial infections are diagnosed annually in the state of Florida alone (Dobos et al., 1999; Lauzardo, pers. comm.) and the incidence is rising (Bilinger et al., 2009). Th is led to the hypothesi s that some environmental parameters are likely affecting the species distribution and density of mycobacteria in the environment, and that changes in these parameters may affect the number and diversity of mycobacteria in an area t hereby altering the relative risk to the general population for NTM infections. Given the ever increasing population of at risk individuals ( Day, 1996; Rappaport, 2007 ), it is more important than ever to understand factors that govern the spread of NTM di sease. This study will provide important insights into the nature of mycobacterial infections within the state of Florida, and will provide a base for further research into epidemiological trends surrounding NTM infections. The following chapters include the development of novel molecular probes for the rapid and accurate detection of NTMs directly from clinical or environmental samples, the investigation of selected surface


68 waterways and municipal distribution systems in Florida for environmental paramet ers governing NTM occurrence and quantities, the evaluation of hospital discharge data for demographical trends of persons hospitalized with NTM disease, as well as spatial analysis of home zip codes of persons hospitalized with pulmonary or disseminated N TM disease. This project was the first to provide field based data examining the functional association between environmental parameters, NTM presence in the environment, and clinical incidence in Florida, and has made much needed inroads to provide linka ges to ultimately discern NTM transmission and risk factors in future studies.


69 CHAPTER 2 NONTUBERCULOUS MYCOBACTERIA DETECTED USING NOVEL QPCR PROBES Background The genus Mycobacterium contains gram positive microaerophilic bacteria, and is one of several mycolic acid containing genera within the order Actinomycetales (Howard and Byrd, 2000; Falkingham, 2003). There are currently thought to be over 130 species of in the genus, with many others still unidentified. Although this genus of bacteria is best kno wn for the causative agents of tuberculosis and leprosy ( M. tuberculosis and M. leprae respectively), the vast majority of mycobacteria are free living environmental species that are opportunistic pathogens. Mycobacteria can be divided into three non phyl etic groups based upon clinical significance. The first grouping is an assemblage of obligate pathogens including the Mycobacterium tuberculosis complex ( M. africanum, M. bovis, M. canettii, M. caprae, M. microti, M. pinnipedii, and M. tuberculosis), and M. leprae and M. lepraemurium that are usually not found in the environment. Non tuberculous mycobacteria, NTMs, comprise the remaining two groups; the facultative pathogens ( M. avium M. marinum M. ulcerans etc.), commonly found in aquatic and terrest rial environments (Covert et al., 1999; Vaerewijck et al., 2005), and the non pathogenic or rarely pathogenic species that are generally saprophytic. (Covert et al., 1999; Vaerewijck et al., 2005 ) NTMs are associated with a variety of chronic, debilitating human and animal diseases. Those within the Mycobacterium avium complex (MAC, i.e., M. avium and M. intracellulare ), are important human pathogens in non immunocompromised persons as well as HIV co infected individuals (Karakousis et al., 2004; CDC, 2005 ; Vaerewijck et al., 2005 ). M. avium ssp. paratuberculosis, the agent of Johne's disease in cattle and


70 other hoofstock also has a significant economic impact on agriculture (Primm et al., 2004). Other human pathogens include M. abscessus, M. kansasii, M marinum, and M. xenopi, which have been associated with pulmonary disease, hypersensitivity pneumonitis, cervical lymphadentitis, osteomyelitis, arthritis, keratitis, tenosynovitis, disseminated disease, otitis media, corneal infections, endocarditis, im munologic dysfunction, and chronic disease states ( Howard and Byrd, 2000; Vaerewijck et al., 2005 ). NTM infection in humans is on the rise, with the number of isolates exceeding those of M. tuberculosis within the United States (Sood et al., 2007). This includes otherwise healthy subjects, particularly middle aged to older, below average weight, caucasian women (Moore, 1993). NTMs are also associated with nosocomial outbreaks and mini epidemics ( Vaerewijck et al., 2005) Clinical diagnosis of NTM disea se is complicated because patients typically present with nonspecific symptoms including fever, anorexia, weight loss, and night sweats. The vagueness of the symptoms often leads to misdiagnosis. Delay in accurate diagnosis is problematic because NTM inf ections are one of the primary reasons for death in immune compromised populations (Howard and Byrd, 2000). Despite this, the epidemiology and ecology of NTM disease remains poorly discerned. The current gold standard for clinical detection is based on id entification of mycobacteria using culture based methods (Wagner and Young, 2003; Griffith et al., 2007). Many mycobacteria, however, are fastidious and difficult to culture due to slow growth characteristics and specific nutrient requirements (Griffith et al., 2007). These techniques obviously provide bias for organisms that are readily cultured (Crosby and


71 Criddle, 2003). As an example, based on culture results, the primary agent of mycobacteriosis in pet birds was previously considered to be M. avium which is relatively easy to culture. Non culture based methods, however, have shown that M. genavense which is difficult to culture, is responsible for up to 96% of companion bird mycobacterioses (Manarolla et al., 2009). Traditional PCR based technique s require a growth enrichment step prior to extraction, and therefore do not allow direct detection of mycobacteria from environmental or clinical samples (Wagner and Young, 2003). Extraction of DNA from mycobacteria is also difficult due to their thick, waxy cell wall (Kotlowski et al., 2004; Griffith et al., 2007), further complicating sensitive detection of these microorganisms in both clinical and environmental samples. Tools for assessing NTMs are needed. The goal of this study was to develop a non culture based, quantitative PCR (qPCR) method of detection for mycobacteria, and to compare physical and chemical DNA extraction techniques. The proposed qPCR techniques do not require culture of the bacteria, and provide selectivity, better sensitivity, and the ability to quantitatively measure relative number of copies from environmental samples (Fang et al., 2002; Crosby and Criddle, 2003). Probes developed through this study will be valuable for determining the relative abundance of NTMs in environmen tal reservoirs, which is expected to correlate with risks to humans, domestic animals, and wildlife. Materials and Methods Primer Development Mycobacterial genus specific primers were developed based on the 16S rRNA gene sequence (Genbank, National Center for Biotechnology Information, Bethesda, MD) from 23 mycobacterial specie s and 6 closely related species. Sequences were


72 aligned and visualized using MUSCLE s oftware ( Edgar, 2004 ) The species of mycobacteria represented all major clades from within the genus level phylogenetic tree ( Migard and Flandrois, 2008 ) DNA sequences from closely related genera in the order Actinomycetales, including Corynebacterium, Rhodococcus, Nocardia, and Actinobacter were also used to represent non Mycobacterium sequence s. Aligned sequences were reviewed for regions of similarity within all mycobacteria that bore inherent differences from the other Actinomycetales. Regions matching such parameters were analyz ed with Primer3 s oftware (Howard Hughes Medical Institute, Che vy Chase, MD) to ensure the feasibility of these primers based on tendency to self bind, melting temperature, size, and G/C content. S equences were then tested for specificity using Primer BLAST (National Center for Biotechnology Information, Bethesda, MD) by scanning all sequences in Genbank and identifying all DNA sequences that might be amplified with the selected primers and probe. The designed primers and probe were synthesized (Applied Biosystems, Foster City, CA). The forward primer ( GAAGAACCTTACCTG GGTTTGACATG ) and reverse primer ( ACAGCCATGCACCACCTGC ) were used to amplify an 88 bp portion of the 16S rRNA gene from roughly positions 920 to 1007 of the published M. fortuitum sequence. The probe ( CAGGCCACAAGGGAAYVSMY ATCTCT FAM fluorescen t label. This development process was repeated to develop primers and probe for MAC using the hsp65 gene. The forward primer ( ACCTGCTCAAGGCCGGYGT ), reverse primer ( GCCTCGGTSGTCAGGAACA ), and probe ( CCGGTGARGGTGWCCCGT ) were


73 used to amplify a 96 bp portion of the hsp65 gene from roughly positions 830 to 926 of the published MAC sequence. S pecificity of both primer sets was confirmed in the laboratory using M. fortuitum, M. sengalense, M. chelonae, M. goodii and M. avium c omplex (MAC), as well as the close ly related species, Rhodococcus equi, Rhodococcus corynebacteroides, Nocardia nova, Nocardia brasiliensis and unrelated bacteria ( Escherichia coli and Vibrio parahaemolyticus ) as negative controls Mycobacterium fortuitum 16S rRNA DNA was used to discern sensitivity of the genus primer/probe set, and Mycobacterium avium subspecies avium Hsp65 DNA was used to examine both the genus and the MAC primer/probe s ets. The standard curve used a 10 fold serial dilution of a Mycobacterium fortuitum 16S rRNA PCR am plicon or a Mycobacterium avium subspecies avium Hsp65 PCR amplicon, ranging from 10 6 to 10 copies The copies per L was calculated by the total amplicon length multipli ed by the average base pair weight (656.6x10 9 ). Each 20 L reaction was run in triplicate, and included 0.9 of each primer, 0.25 of probe, 1 L DNA extract and 10 L of a commercial universal qPCR mix (TaqMan Fast Universal PCR Master Mix, Applied Bios ystems, Carlsbad, CA). A 7500 Fast Real Time PCR System (Applied Biosystems, Carlsbad, CA) was used to amplify the reaction with the standard fast protocol : initial denaturation at 95C for 20 sec; 40 cycles of 95C for 3 sec followed by 60C for 30 sec Data was analyzed using the 7500 Software v2.0.3 (Applied Biosystems, Foster City, CA). Serial Dilutions Mycobacterium fortuitum (ATCC 6841) and M. avium subspecies avium (ATCC 700898) cultured on were used to provide master


74 standards for subsequent dilutions and extraction protocols. Inocula from each of the two mycobacteria cultures were used to prepare a 1.0 McFarland standard in T E buffer (Promega, Madison, WI). S uspensions were mixed thoroughly to minimize clumping and a series of ten fold dilutions were derived Aliquots from each dilution were frozen at 20 C for subsequent DNA extraction via physical methods with traditional PCR amplification, or extractio n via chemical methods with qPCR amplification. A separate aliquot of 75 L from each dilution series was plated onto replicate Middlebrook 7H10 plates and incubated at 35 C for 7 days to determine colony counts. Two p lates from each dilution series were u sed to generate approximate colony forming units (CFU) numbers. After 7 days of growth at 35 C, the plates from the dilution series were examined. CFU numbers were generated for each plate (Table 1) Standard calculations were then performed to determine t he approximate CFU/ mL for each dilution in the dilution series. Extraction by Physical Disruption A liquots of bacterial dilutions from the two mycobacteria species were placed into a pre heated 95 C water bath for 15 minutes. The heat killed solutions wer e vortexed at low speed, and 400 L of each dilution was added to a new tube containing 25 L of sterile 0.1 mm glass beads. Suspensions were agitated at high speed via vortexer (Fischer Scientific, Pittsburgh, PA) for 5 minutes, and then centrifuged at 13, 500 x g for 15 minutes. Supernatant ( ~ 350 L ) from each dilution was transferred to a new tube and re centrifuged at 13,500 x g for 15 minutes. Aliquots of supernatant were frozen at 20 C. This physical DNA extraction is standard operating protocol for h andling clinical samples at a NTM diagnostic reference laboratory.


75 Extraction by Chemical Disruption DNA was also extracted through chemical disruption via a commercially available kit Qiagen DNeasy Blood and Tissue ( Valencia, CA ) Cells were lysed usi ng proteinase K and DNA was purified through a silica membrane Frozen, serially diluted bacterial samples were brought to room temperature and centrifuged for 15 minutes at 21,000 x g. The supernatant was carefully removed from each tube to av oid disturb ing the pellet. DNA was extracted from the p ellets using the Qiagen DNeasy Blood and instructions ( Valencia, CA ) DNA extracts were held at 4 C until ready for use. F ast qPCR reactions were performed as described above to compare the efficiency of physical versus chemical extraction methods. Comparison of qPCR and Traditional PCR To demonstrate the utility of these novel primers, we examined detection limits of DNA isolated via physical disruption (as des cribed above) via both qPCR and traditional PCR. 3 L and 5 L starting quantities of each of these reactions were subjected to 1% gel electrophoresis PCR was performed using the mycobacterial Tb11 and Tb12 primers as previously described (Shinnick, 1987; Ringuet et al., 1999 ) to verify successful DNA extraction. Each dilution was subsequently subjected to qPCR testing as described above. Results Primer Sensitivity and Specificity Specificity of the genus specific primers was confirmed by positive qPCR re sults on DNA from M. fortuitum, M. sengalense, M. chelonae, M. goodii and M. avium Complex (MAC), as well as negative results on the closely related species,


76 Rhodococcus equi, Rhodococcus corynebacteroides, Nocardia nova, and Nocardia brasiliensis and th e unrelated species Escherichia coli and Vibrio parahaemolyticus (Figure 2 1). DNA from all bacteria within the Mycobacterium genus were amplified above the threshold of detection, while DNA from other species failed to cross the threshold of detection. S imilarly, the MAC qPCR assay specificity was confirmed by positive results with MAC and negative results with M. fortuitum M. goodii M. sengalense N. nova N. brasiliensis R. equi R. corynebacteroides E. coli and V. parahaemolyticus (Figure 2 2) S ensitivity testing found that b oth the genus and MAC standard curves demonstrated the ability to detect down to 10 DNA copies (Figure 2 3) We did not test for detection below this level. The standard curve for the genus specific qPCR assay had a slope of 3.42 and a high correlation coefficient (R 2 ) of 0.998, and the standard curve for the MAC qPCR assay had a slope of 3.33 and a high correlation coefficient (R 2 ) of 0.996. Chemical versus Physical Disruption Since DNA extraction from mycobacteria is kno wn to be challenging, we compared the physical versus the chemical extraction methods of the same dilution series of 2 different mycobacterial species, M. fortuitum and MAC. The limit of detection for the physical disruption extraction of both M. fortuitu m and MAC was 10 3 CFU/ mL (Figure 2 5). Chemical disruption of M. fortuitum and MAC, however, were both d etected at the level of 1 CFU/ mL (Figure 2 5), a 3 fold increase in the level of detection. Culture Confirmation After 7 days of growth, the dilution series of M. fortuitum and MAC colonies were assessed based on colony counts from replicate culture plates. Colonies were


77 enumerated and calculations were made from the dilution with counts between 50 300 to estimate the number of bacteria throughout the series ( Table 2 1). Comparison of qPCR and Traditional PCR Results of traditional PCR indicated that only dilution 1 (~ 10 7 ) was visualized for M. fortuitum and dilutions 1 3 (~ 10 5 ) of MAC are clearly visualized with partial visualization of dilution 4 (~ 10 4 ) for MAC (Figure 2 4). Thus, the limit of detection for DNA extracted using physical disruption, visualized using traditional PCR, is 10 4 10 7 copies For direct comparison, the same DNA was tested using the qPCR technology as described above. This me thod demonstrated reliable detection down to 10 3 CFU/ mL for both M. fortuitum and MAC (Figure 2 5). Partial detection was also observed at 10 2 in both M. fortuitum and MAC; at this level, however, with 1/3 of M. fortuitum and 2/3 of MAC triplicate reactio ns crossing the threshold of detection. In summary, the level of detection for the physical disruption extraction was above 10 3 using qPCR and above 10 5 using traditional PCR. Discussion Data from this study demonstrates that the qPCR probes have a notabl y better sensitivity for NTMs than traditional PCR. DNA extracted by physical disruption and then subjected to standard PCR amplification required at least 10 6 bacteria or more for detection. Further, BLAST a nalysis (National Center for Biotechnology Inf o rmation, Bethesda, MD) of the Tb11 and Tb12 primers reveal ed that they can amplify mycobacteria as well as closely related actinomycetales ( Steingrube et al., 1997 ), thus suggesting the potential for false positives using this method.


78 T he qPCR method used in this study provided excellent s pecificity for mycobacteria ( Figure 2 1 ). The graph of these results show that only mycobacteria were amplified, and that neither the closely related actinomycetales, R equi, R corynebacteroides, N nova, and N brasil iensis nor the unrelated bacteria, E coli and V parahaemolyticus were amplified using these primers. This increased specificity is critical for detecting low levels of mycobacteria Environmental samples, for example, often contain a host of bacteria l species, and being able to say with confidence that the bacteria in a sample are actually mycobacteria could yield new insights into the true composition of the flora. Additionally, the use of qPCR in the analysis of environmental samples allows for qua ntization of the relative abundance of mycobacteria which a standard PCR and gel electrophoresis cannot provide. An additional benefit of qPCR is t he added sensitivity. T he detection limit of the standard PCR and gel electrophoresis was approximately 10 6 bacteria per mL whereas the qPCR data showed detection down to approximately 10 2 bacteria per mL from the same extraction. This added sensitivity could be of major importance in a clinical diagnostic lab. Mycobacteria are often notoriously difficult to culture and detect, allowing for many inherent delays in the time before proper diagnosis and treatment can begin. This study also finds chemical disruption to be a better extraction method than physical disruption, detecting two orders of magnitude lowe r CFU counts. Further, the physical disruption method showed variability of detection at the 10 2 CFU/ mL level; at this level, only 1/3 of M. fortuitum and 2/3 of MAC triplicate samples crossed threshold. Thus, we can only show confidence in detection down to the 10 3 CFU/ mL level using


79 the physical disruption method. Chemical disruption provided a 3 fold increase in our detection level, ~1 CFU/ mL (Figure 2 5), as compared with physical disruption It is important however, to note that mycobacteria are know n to clump. Thus, one CFU may not correlate with one mycoba c terial cell. Thus, we are not implying that we can detect 1 bacterial cell, despite our results indicatin g the ability to detect 1 CFU/ mL N on culture based, molecular probes provide an improve d approach to diagnosing clinical mycobacterial cases. Current standards require culture, which can prove exceedingly difficult given the variety of temperature requireme nts and media requirements for the different mycobacteria ( Falkingham 2003; Griffith e t al., 2007 ). These specimens are then subjected to PCR amplification using primers shown to amplify non mycobacterial Actinomycetales as well as mycobacteria ( Steingrube et al., 1997 ). Here we demonstrate a method for detection tha t allows for higher se nsitivity and specificity, without the biases and need for weeks of growth involved in standard culture based methods for detection of mycobacteria.


80 Table 2 1. CFU and calculated CFU for serial dilutions of mycobacterial cultures. Dilution Series Plate Count Estimated CFU/ mL M. fortuitum 1 TNC 1.7 x 10 7 M. fortuitum 2 TNC 1.7 x 10 6 M. fortuitum 3 TNC 1.7 x 10 5 M. fortuitum 4 616 1.7 x 10 4 M. fortuitum 5 53 1.7 x 10 3 M. fortuitum 6 3 1.7 x 10 2 M. fortuitum 7 0 17 M. fortuitum 8 1 1.7 MAC 1 TNC 1.3 x 10 7 MAC 2 TNC 1.3 x 10 6 MAC 3 TNC 1.3 x 10 5 MAC 4 464 1.3 x 10 4 MAC 5 48 1.3 x 10 3 MAC 6 1 1.3 x 10 2 MAC 7 0 13 MAC 8 0 1.3 Note: TNC indicates a plate with colonies too numerous to count.


81 Figure 2 1. Genus Specificity Curves. Ampl ification of bacterial DNA showing specificity of genus spe cific primers. Only mycobacteria ( M. fortuitum M. goodii M. sengalense and MAC) crossed the threshold for detection, showing specificity of the prime rs and probe for mycobacteria. Nocardia nova Nocardia brasiliensis Rhodococcus equi Rhodococcus corynebacteroides and Esherichia coli were also tested, but failed t o cross threshold of detection. Additionally, Vibrio parahaemolyticus was also tested, but fluorescence was not d etected at any point measured. Error bars = SD from triplicate PCR runs.


82 Figure 2 2. MAC Specificity Curve Amplification of bacterial DNA showing specif icity of MAC specific primers. Only MAC DNA crossed the threshold of detection, while M. fortuitum M. goodii M. sen galense Nocardia nova Nocardia brasiliensis Rhodococcus equi Rhodococcus corynebacteroides Esherichia coli Vibrio parahaemolyticus did not. Error bars = SD from triplicate PCR runs.


83 Figure 2 3. Standard Curves. A) Mycobacterium genus specific a nd B) MAC specific standard curves. Curves generated from dilution series ranging from 10,000,000 copie s down to 10 copies of DNA. Data indicate detection limit of 10 copies of DNA per mL sample. Error bars = SD from triplicate PCR runs.


84 A B Figure 2 4 Traditional PCR Results. Gel electrophoresis to discern limit of detection of A) M. fortuitum and B) MAC In each gel, lanes 1 2 represent dilution 1, 3 4 dilution 2, etc with the ladder inserted centrally for optimal visualization. For M. fortuitum only dilution 1 is visualized. For MAC, dilutions 1 4 are visualized. The positive control for both was run in lane 18 on the MAC gel.


85 Figure 2 5. qPCR Results. qPCR results from dilution series of M. fortuitum and MAC extracted using A) physical an d B) chemical disruption methods. The physical disruption method showed reliable detection down to approximately 10 3 CFUs/ mL with partial success at 10 2 CFUs/ mL Partial success was defined only one or two of the triplicate amplifications crossing threshold. Threshold of detection (0.016921) was the same for eac h of the 4 datasets presented. The chemical disruption method showed reliable detection for both M. fortuitum and MAC down to approximately 1 CFU/ mL in each of the triplicate samples amplified. Error b ars = SD.


86 CHAPTER 3 NONTUBERCULOUS MYCOBACTERIA IN FLORIDA SURFACE AND MUNICIPAL WATERS Background Mycobacteria are a highly diverse, species rich assembledge of bacteria within the genus Mycobacterium Although mycobacteria are commonly associated with tuberculosis and leprosy ( cased by M. tuberculosis and M. leprae respectively), the vast majority of mycobacteria are free living environmental species that are opportunistic pathogens of humans and wildlife. Environmental mycobacteria, collectively kno wn as nontuberculous mycobacteria (NTMs), are ubiquitous throughout a broad range of habitats ranging from soils and surface waters to hot tubs swimming pools, fish tanks, and municipal water distribution systems (Kirschner et al., 1992; Katila et al., 1 995; Langevin et al., 1999; Falkingham, 2003; Primm et al., 2004; Vaerewijck et al., 2005; Field and Cowie, 2006; Sood et al., 2007). Water chemistry has been reported to influence the presence and distribution of NTMs in surface waters (Falkinham et al. 2001; Primm et al., 2004), although there is a lack of published data to substantiate this. Notably, Florida and the southeastern US are associated with study sites that have recovered many NTM isolates (Falkingham 1996), and this region appears to have a relatively high incidence of human NTM disease (Dobos et al., 1999; Reed et al., 2006). NTMs relevant to human disease include species and subspecies within the Mycobacterium avium complex (MAC), as well as M. kansasii, M. fortuitum, M. chelonae, M. gas trii, M. scrofulaceum, M. ulcerans and others ( Howard and Byrd, 2000; Vaerewijck et al., 2005 ; Griffith et al., 2007 ). I nfection s with these bacteria are associated with pulmonary and disseminated disease s hypersensitivity pneumonitis,


87 cervical lymphade ntitis, osteomyelitis, arthritis, keratitis, teno synovitis, otitis media, corneal infections, endocarditis and immunologic dysfunction ( Horsburgh, 1996; Howard and Byrd, 2000; Vaerewijck et al., 2005; Griffith et al., 2007 ). The frequency of NTM infection s appears to be increasing in both healthy and immunocompromised subjects particularly in the southeastern US (Primm et al., 2004). H uman exposure to NTMs is associated with water exposure, involving some combination of drinking water or ingestion of fi eld irrigated leafy vegetables inhalation of aerosols during show er ing, use of hot tubs, and contact with fish or natural surface waters (Witty et al., 1994; Yajko et al., 1995; Eaton et al., 1995; Falkingham, 1996; Yoder et al., 1999; Argueta et al., 200 0; Pedley et al., 2004; Primm et al., 2004 ) A variety of mycobacteria, including M avium, M. chelonae, M. fortuitum, M. gordonae, M. kansasii, and M. xenopi have been reported from municipal water distribution systems ( Fischeder et al., 1991; Glover et al., 1994; Covert et al., 1999; Falkingham et al., 2001 ; Vaerewijck et al., 2005 ; Falkingham, 2011), and treatment with chlorination or chloramination is believed to have little effect on their presence (Taylor et al., 2000; Vaerewijck et al., 2005). W at er use patterns and diet may alter individual exposure risk (Vaerewijck et al., 2005). This study applied novel Mycobacterium genus and MAC specific qPCR probes to discern the presence and density of mycobacteria in surface and municipally distributed wat er in Florida, and examine possible water quality relationships that might relate to mycobacterial density in these waters. Materials and Methods De identified areas in Florida were chosen for water sampling based on regional proximity to municipal water d istribution systems, housing developments that


88 incorporate landscape scale surface water features, and irrigation canals associated with agriculture The two m unicipal water distribution systems were sampled to represent source water from the Floridan and the Biscayne aquifer. Sampling for M ycobacterial DNA Water samples for mycobacterial quantification were all collected on February 16 th 2010 using sterile 50 mL conical tubes (VWR Scientific, West Chester, PA ) S urface waters were collected from the ai r/water interface. S amples from the two municipal water distribution facilities were taken from sampling valves, immediately up and downstream from the treatment /distribution facilities, as initial bol uses without flushing Filled tubes were capped, imm ediately placed on ice transported to the laboratory and frozen at 20 C until processing, within 48 hours. D uplicate sample tubes were taken from each sampling site for water chemistry that, depending on the analysis, were processed at the time of colle tion in the field or laboratory analyzed the same day DNA Extraction DNA was extracted from thawed water samples using a combination of both chemical and physical disruption. Upon thawing to room temperature and mixing, 1 mL of sample was centrifuged at 2 1,000xg for 15 minutes. DNA was extracted from the resulting pellet using the PowerBiofilm DNA Isolation Kit directions ( MO BIO Laboratories Inc., Carlsbad, CA ). DNA extraction product s were held at 4 C until ready to use. Quantitati ve PCR (q PCR) Three primer/probe com binations were used to quantify pan bacterial DNA, genus specific mycobacterial DNA, and MAC specific DNA. For pan bacterial DNA, the universal primer/probe set targeted the 16s rDNA gene as described by Nadkarni et a l.,


89 ( 2002). Genus specific mycobacteria primers and MAC specific primers targeted the mycobacterial 16s rDNA and hsp65 gene s respectively (Yarnell et al., 2011). Briefly, each 20 L and L of extracted DNA and 10 L of a commercial universal qPCR mix (TaqMan Fast Universal PCR Master Mix, Applied Biosystems, Carlsbad, CA) using a standard fast protocol. Mycobacterium fortuitum 16s r DNA was used as a control for the genus primer/probe set, and Mycobacterium avium subspecies avium h sp65 DNA was used as the control for the MAC primer/probe set. A standard curve, ranging from 10 to 10 6 copies was run on each plate, and contained a 10 fold dilution series of a Mycobacterium fortuitum 16s rRNA PCR amplicon or a Mycobacterium avium subspecies avium h sp65 PCR amplicon. A 7500 Fast Real Time PCR System (Applied Biosystems, Carlsbad, CA) was used to amplify the reaction with cycling conditions as follows : initial denaturation at 95C for 20 sec; 40 cycles of 95C for 3 sec followed by 60C for 30 sec (see Figure 3 1 ). Conformation of N ear T hreshold qPCR D ata S amples with a cycle threshold (C t ) less than 10 copies were c onfirmed using hemi nested PCR (this applied to MAC samples only, based on data collected). The CGCCACCGGTGAGTACGAG ) CGCCTTCTCCGGCTTGTC ) for the first round, and forward primer MAC FP and reverse primer MAC RP as a second round (Yarnell et al., 2011). Amplifications were performed using an Eppendorf AG Mastercycler (Eppendorf, Hamburg, Germany), using Platinum Taq DNA Polymerase (Invitrogen, Carlsbad, CA) with the following conditions: 15 min denaturation at 95C, f ollowed by 40 cycles of denaturation at 95C (30 sec), annealing at 59C (30 sec), extension at 72C (30 sec),


90 with a final elongation step at 72C for 10 min. Amplification products, along with, positive control DNA, positive environmental DNA, a no temp late control, and an open air negative control were run in 1% agarose gels, and bands of interest were excised from the gel and extracted using the Qiaquick gel extraction kit (Qiagen Valencia, CA). Direct sequencing was performed using the Big Dye Ter minator Kit (Applied Biosystems Foster City, CA) and ABI automated sequencers ( DNA Sequencing Facilities, Center for Mammalian Genetics, University of Florida) Sequences received two fold coverage in each direction. Sequence results were reviewed usi ng 4Peaks Software ( Mekentosj Amsterdam, NL), and aligned and visualized using MUSCLE Software ( Edgar, 2004 ). Culture Confirmation Culture techniques were used to confirm the presence of mycobacteria in water samples analyzed using molecular probes. A s ubset of water samples, representing surface water collection sites as well as municipal water distribution lines, were plated onto selective 7H11 medium plates containing 10 g mL 1 malachite green, 36 g mL 1 cycloheximide, 50 g mL 1 ampicillin, and 25 U m L 1 nystatin, and incubated at 35C for > 2 weeks (Bland et al., 2005). Subsequent colonies were subcultured onto standard Middlebrook 7H11 medium plates incubated for 10 days, and then acid fast stained. Acid fast positive colonies were extracted for D NA, amplified using PCR and sequenced C onfirmatory nested PCR targeted the ITS1 region of the 16s rDNA gene using forward primer ITS16F (Whipps et al., 2003) and reverse primer SP2R (Roth et al., 2000) for first round and forward primer SP1F (Roth et al., 2000) and reverse primer SP2R (Roth et al., 2000) for the second round. Amplifications were performed on an Eppendorf AG Mastercycler (Eppendorf, Hamburg, Germany) using Platinum Taq


91 DNA Polymerase (Invitrogen, Carlsbad, CA) as follows: 15 min denatu ration at 95C, followed by 40 cycles of denaturation at 94C (1 min), annealing at 58C (1 min), extension at 72C (1 min), with a final elongation step at 72C for 10 min. Products were prepared for sequencing as described in the previous section. Wate r C hemistry Temperature, pH, conductivity, and dissolved oxygen were measured in the field using a YSI pH10 meter, a YSI 33 SCT conductivity meter, and a YSI 55 dissolved oxygen meter (YSI Incorporated, Yellow Springs, OH), respectively. Other analyses, discerned using standard EPA laboratory methods (EPA, 1993; Clescerl et al., 1999), included dissolved organic carbon by (SM 5310 C method), nitrates+nitrites (EPA 353.2 method), total and dissolved phosphorous (EPA 365.1 method), total and dissolved Kjel dahl nitrogen (EPA 351.2 method), and total and dissolved nitrogen by calculation. Statistics Statistical differences between sampling sites were assessed for water chemistry parameters and relative bacterial loads using a Mann Whitney test, and correlatio ns were evaluated using Pearson correlation. Statistical tests were run in SPSS ( IBM Corporation, Somers, NY ). P values of < 0.05 were considered statistical significant. Results Quantification Bacterial counts were estimated based on qPCR reactions agai nst a standard curve. E stimated bacterial count s, based on number of DNA copies, revealed that the pan bacterial count >>> mycobacteria genus count > MAC count ( Figure 3 1 ). The majority of the bacteria detected were not mycobacteria My cobacteria, incl uding MAC,


92 however, were detected in all samples tested from surface waters associate with housing developments, agricultural irrigation canals, and municipal water distribution systems Several patterns emerged from the bacterial count estimates from mun icipal water distribution systems : (1) the number of total bacteria in Floridan and Biscayne aquifer sources was reduced by municipal treatment prior to distribution (P=0.002) (Table 3 2); (2) distribution water from Municipal System 1 had higher mycobacte rial genus counts than Municipal System 2 distribution water (P= 0.027) and (3) estimated counts for mycobacteria were not reduced by municipal treatment (P=0.395; Table 3 2) unl ike total bacteria counts Additionally, while treated municipal samples had lower estimated total bacterial and mycobacteria compared with environmental surface water samples, municipal samples had a notably higher percentage of mycobacteria in the total bacterial load co mpared to environmental samples ( 0.03 1.07%, compared with 0.51 2.63%; P=0.001). This trend appeared to be correlated with pH ( P<0.001) across all sample sit es (Figure 3 2 ). MAC was detected in all municipal and surface water samples tested albeit near the limit of detection Therefore t o differentiate whether these data represented true low level detection (between 1 and 10 DNA copies) or false read s MAC samples were screened using heminested PCR PCR and Sequencing To rule out false negatives due to limitations of threshol d of detection, samples with a c ycl e threshold (C t ) less than 10 copies were confirmed with hemi nested PCR. Only MAC qPCR products showed C t ) < 10 copies, hence hsp65 gene n ested primer sets were used for targeting. Heminested PCR products (electrophoresis bands ) were


93 extracted and sequence d and aligned and compared against published h sp65 sequences in Genbank ( National Center for Biotechnology Information, Bethesda, MD ) for MAC and other closely related Actinomycetales Sequences from extracted bands matched published MAC sequence s and w ere confirmed as MAC using both BLAST analysis ( National Center for Biotechnology Information, Bethesda, MD ) and manual comparison. These results suggest that bands visualized from the heminested PCR confirmed the presence of MAC in these samples, many at low copy rates. Culture Confirmation M ycobacteria were isolated from 4/8 municipal water samples, representing both treatment facilities yielded 10 colonies, and 13/15 surface water samples yielded 21 colonies Sequence results from these cultured isol ates were confirmed to be M intracellulare, M abscessus, M chelonae, M avium subspecies avium, M fortuitum, M immunogenum, M gordonae, and M flavescens (Appendix ). Water Quality Water chemistry data from all sample sites are presented in Table 3 1 alongsid e estimated bacterial counts. All water quality parameters were graphed (data not shown) and were observed for trends in estimated mycobacteria ( genus level) c ounts No trend, positive or negative, from any single water quality parameter was ob served in relation to the presence or density of genus level mycobacteria. There were, however, differences in water chemistry between discharge (i.e., post treatment) water from Municipal 1 and Municipal 2 distribution systems. Municipal 1 discharge had higher total and dissolved phosphorous (P < 0.001 ) and lower dissolved organic carbon (P < 0.001 ) compared to Municipal 2 discharge samples (Table 3 1). It is not clear, however, if these differences are related to the positive 2 fold difference in


94 estimat ed mycobacterial counts (4,239 1,634 versus 2,532 1,119 respectively; Table 3 1) since other factors could be associated with these differences Discussion This study demonstrated the presence and relative density of NTMs in environmental and municipa l water samples in Florida using quantitative PCR methodology Analyses from surface water samples taken proximal to housing communities, agricultural irrigation canals, as well as municipally distributed potable water, all revealed the presence of mycoba cteria including species within the Mycobacterium avium complex. E stimated tota l bacterial counts and genus level mycobacteria counts from environmental samples were within the range of observations previously reported ( Table 3 3 ). In general, qPCR base d estimates of bacterial counts are typically greater than culture based CFU inventories due to the comprehensive detection of all DNA by qPCR (Boehm et al ., 2009; Walters et al ., 2009; Bae and Wuertz 2009; Lavender and Kinzelman 2009; Byappanahalli et al 2010). Thus, it is reasonable that our estimates are at the higher end of the range o f reported culture based data (Table 3 3) Growth of mycobacteria within potable water distribution systems has been well documented (Fischeder et al., 1991; Glover et al., 1994; Covert et al., 1999; Falkingham et al., 2001; Falkingham, 2011). This study demonstrated the presence of mycobacteria and MAC species within two drinking water distribution systems in South Florida. These data also suggest that the effectiven ess of chloramine treatment of municipal distribution water for removing or reducing mycobacteria is relatively poor compared with the overall bacterial population (Table 3 2).


95 R esistance to chemical disinfectants such as chlorine, monochloramine (the di sinfectant used in these facilities), chlorine dioxide, and ozone is associated with the relatively high concentration of mycolic acids in mycobacteria l cell walls that imparts a reduced efficacy of these treatments on mycobacteria (Taylor et al., 2000; V aerewijck et al., 2005). Thus, differences noted between the municipal post treatment waters may be associated with (1) differences in the mycobacterial species/strain composition in the respective (Floridan versus Biscayne aquifer pre treatment) source w aters and (2) the species composition of mycobacteria post treatment based on a combination of both species and strain susceptibility to disinfectants (Taylor et al., 2000). These differences are reasonable since the two municipal systems are supplied b y two different aquifers, Floridan and Biscayne, that vary in water quality ( Fernald and Purdum, 1998 ). Municipal samples, regardless of the aquifer water source, had a higher relative proportion of mycobacteria than environmental samples (Table 3 1), ass ociated primarily with the effective reduction of the pan bacterial population associated with chloramine disinfection. Small sample sizes in this initial study precluded comparison of mycobacterial loading between pre treatment sources. In an effort to b etter understand post treatment differences, however, water quality parameters were examined for differences between the two municipal distribution facilities. Municipal 1 post treatment samples revealed higher levels of total and dissolved phosphorous co mpared with Municipal 2 post treatment samples (Table 3 1). The source of phosphorous in Municipal 1 distribution water was the addition of AquaCros (Harcrocs Chemicals Inc., Kansas City, Kansas) at the water treatment


96 facility. This additive, used to r educe pipe corrosion within older neighborhoods, was not added to Municipal 2 post treatment waters, and elevated phosphorous was not noted in these waters. Phosphorous has previously been linked to enhanced microbial growth (Appenzeller et al., 2001; Vae rewijck et al., 2005 ; Torvinen et al., 2007), and so mycobacterial growth may be aided by added phosphorous, especially in municipal sources where general bacterial competition is reduced by chlorinamination. Mycobacterial numbers relative to total bacter ia counts may be influenced by pH. When we evaluated water quality parameters and the percentage of mycobacteria relative to the total bacterial counts in bo th municipal and surface waters, a higher mycobacteria l contribution to the pan bacterial counts w as positively correlated with higher pH (Figure 3 2 ). This is consistent with M. fortuitum studies conducted by Farooq et al. (1977) where NTM survival was higher at pH 10.1 compared with pH 5 .7 to 10.1 Phosphorus levels and the relationship between pH and the relative contribution of mycobacteria to the total bacterial load may be important constructs to focus on in follow up studies However, water quality and biological factors driving the growth of environmental mycobacteria remain unclear. Regardl ess, t his study contributes to a growing body of literature demonstrating the growth of mycobacteria within municipal distribution lines (Falkingham et al., 2001; Briancesco et al., 2010; Falkingham, 2011) ; this time in South Florida Previous studies ha ve demonstrated high exposure rates to MAC in S outh Florida based on antigenic skin reactivity (Reed et al., 2006 ) implying there must be an environmental source for these in this area. Our study found NTMs and MAC to be


97 ubiquitous in the environment, a lbeit with MAC at very low levels. The apparent low levels found in our study does not eliminate these as possi ble sources of infection. The minimum infectious dose, defined as the minimum amount of bacteria within a sample required to cause disease is frequently used to determine the infectious level of a certain quantity of disease organisms Exposure to doses below this level will not result in disease, whereas doses in excess will, with increasing probability, result in disease (French et al., 2002), such that a large inoculum of organisms increases the chance of infection (McCue, 1990). This has been demonstrated in organisms such as Salmonella E. coli Foot and mouth disease virus, and mycobacteria (Shepard et al., 1965; Blaser and Newman, 1982; T uttle et al., 1999; Alexandersen et al., 2002; French et al., 2002). T he infectious dose levels also vary between modes of transmission (French et al., 2002; Alexandersen et al., 2002) which is particularly significant for pathogen transmission from the environment, where numbers are often low (Smith and Rose, 1990). Mycobacteria are thought to grow along the length of distribution lines in the form of biofilms ( Falkingham et al., 2001; Briancesco et al., 2010; Falkingham, 2011 ). Indeed, m ycobacterial numbers were previously shown to be on average 25,000 fold higher in distribution systems than immediately post treatment (Briancesco et al., 2010) consistent with the idea of growth along the length of the pipeline Therefore, NTM numbers at the househo ld level could potentially be higher than those detected close to the treatment facility (Falkingham et al., 2001). Within the home NTMs may form biofilms in stagnant water lines, washing machines, whirlpools, showerheads, etc. and


98 may provide exposure levels leading to infection ( Primm et al., 2004; Griffeth et al., 2007; Feazel et al., 2009). Biofilm s undergo a continuous process of gro wth and detachment of aggregates, which can lead to the ingestion or inhalation of condensed infective dose s (Hall S t oodley and Stoodley, 2005). This detachment process is well studied under fluid flow and is affected by changes in flow rate (Stoodley et al., 1998; Stoodley et al., 2001). Detached particles can contain high numbers of organisms within a small area such that pathogen cell densities may reach 10 7 cells/cm 2 (Hall Stoodley and Lappin Scott, 1998). Such detachments have been previously noted in mycobacteria (Asuncion et al., 1999; Stoodley et al., 2001), and so it has been suggested that NTM biofilms may dis perse large clumps of mycobacteria into waters and aerosols (Hall Stoodley and Stoodley, 2005) thereby potentially contributing to NTM transmission by facilitating a sufficient infective dose to be ingested, inhaled or abraded into the skin (Hal l Stoodley and Stoodley, 2005). South Florida is densely populated, has an ever increasing high risk population of children, elderly, and immunocompromised persons and is a major tourist destination. Therefore, understanding the ecology of NTMs in s outh Florida is important and requires further exploration. This study attempted to identify variables regulating the growth of NTMs in both environmental and municipal sources using a quantifiable method of detection. This study suggests mycobacteria are ubiquitous in surface and municipal distribution water s, and that further studies are essential in order to discern environmental reservoirs, exposure pathways and risk factors associated with NTMs and associated infections.


99 Table 3 1. Water quality data pan bacteri al c ounts, mycobacteria counts and percentage mycobacteria from municipal and environmental water samples A B C D E F G H I J K L M Mun1 2.49 243,526 6,068 439 0.13 6.06 8.89 0.44 0.44 0.95 1.00 20.1 Mun1 1.91 213,372 4,079 446 0.13 6.92 8.98 0.43 0.44 1.06 0.83 22.3 Mun1 1.47 213,247 3,141 428 0.18 7.06 8.64 0.43 0.42 1.04 1.05 21.0 Mun1 0.99 265,742 2,639 429 0.10 6.95 8.94 0.41 0.42 1.10 0.91 21.5 Mun1 2.63 231,582 6,080 411 0.14 6.51 9.01 0.48 0.46 0.98 0.98 18.1 Mun1 2.35 265,819 6,234 423 0.16 7.13 8.91 0.42 0.41 1.02 0.70 20.8 Mun1 1.28 195,934 2,500 407 0.18 4.67 9.00 0.41 0.40 0.97 0.90 20.9 Mun1 2.02 157,000 3,168 405 0.15 5.91 8.99 0.41 0.40 0.93 0.94 21.4 Avg 1.89 223,278 4,239 424 0.15 6.40 8.92 0.43 0.42 1.01 0.91 20.8 Stdev 0.60 36, 705 1,634 15 0.03 0.84 0.12 0.02 0.02 0.06 0.11 1.2 Mun2 1.31 295,539 3,885 195 1.58 9.34 9.06 0.03 0.03 1.29 1.19 19.0 Mun2 0.99 157,839 1,557 193 1.42 7.65 9.10 0.02 0.03 1.20 1.18 20.5 Mun2 0.99 150,679 1,490 193 1.78 7.81 9.09 0.03 0.0 3 1.13 1.12 19.4 Mun2 1.29 194,524 2,515 204 1.39 5.45 9.10 0.02 0.02 1.04 1.07 20.5 Mun2 2.48 181,850 4,517 228 1.80 6.46 9.13 0.04 0.02 1.14 0.94 17.9 Mun2 0.70 250,870 1,764 198 1.57 5.07 8.87 0.03 0.03 1.24 1.03 15.0 Mun2 1.11 233,261 2,595 183 1.6 7 5.06 8.87 0.04 0.03 1.03 1.06 15.0 Mun2 0.51 379,868 1,929 180 1.67 5.42 9.05 0.02 0.02 1.04 0.79 23.2 Avg 1.17 230,554 2,532 197 1.61 6.53 9.03 0.03 0.03 1.14 1.05 18.8 Stdev 0.60 77,713 1,119 15 0.15 1.58 0.10 0.01 0.01 0.10 0.13 2.8 SurfA 0.09 15,437,705 13,355 2,110 23.80 6.50 7.80 0.06 0.03 2.83 2.78 18.0 SurfA 0.34 1,641,078 5,586 1,150 29.40 7.60 8.10 0.05 0.05 3.50 3.49 16.0 SurfA 0.47 3,030,670 14,147 1,490 29.70 12.50 8.50 0.03 0.03 2.85 2.64 16.5 SurfA 1.07 14,919,250 160,3 37 1,250 33.10 6.20 8.80 0.79 0.15 6.83 3.75 20.0 Avg 0.49 8,757176 48,356 1,500 29.00 8.20 8.30 0.23 0.07 4.00 3.17 17.6 Stdev 0.42 7,439,363 74,754 431 3.85 2.93 0.44 0.37 0.06 1.91 0.54 1.8 SurfB 0.32 4,278,803 13,604 425 12.50 9.40 8.2 0 0.09 0.08 0.94 0.76 18.5 SurfB 0.50 1,291,208 6,425 415 12.50 8.80 8.10 0.09 0.08 0.97 0.84 18.0 SurfB 0.39 2,829,216 10,983 410 13.20 8.90 8.30 0.09 0.08 0.59 0.53 18.0 Avg 0.40 2,799,742 10,338 417 12.73 9.03 8.20 0.09 0.08 0.83 0.71 18.2 Stdev 0.0 9 1,494,016 3,633 8 0.40 0.32 0.10 0.00 0.00 0.21 0.16 0.3 SurfC 0.37 2,753,082 10,099 355 12.20 7.50 7.50 0.12 0.11 0.95 0.66 17.0 SurfC 0.03 13,072,934 3,901 360 12.20 9.70 7.70 0.09 0.08 0.73 0.55 16.5 SurfC 0.28 6,578,069 18,141 405 11 .10 7.70 7.50 0.17 0.12 0.93 0.83 18.0 SurfC 0.17 7,711,563 13,395 230 7.52 9.70 7.60 2.41 2.35 0.65 0.52 15.6 SurfC 0.51 1,899,708 9,626 240 12.90 9.40 8.00 0.05 0.02 1.05 0.69 17.0 SurfC 0.51 2,409,751 12,394 320 12.50 8.80 8.10 0.06 0.03 1.42 1.13 19 .0 SurfC 0.50 1,079,535 5,408 350 9.33 9.70 8.20 0.02 0.02 1.29 1.30 18.0 SurfC 0.57 2,684,834 15,254 285 8.18 8.70 8.10 0.04 0.03 0.67 0.64 19.0 Avg 0.34 5,072,092 10,423 323 11.11 8.93 7.80 0.42 0.39 1.00 0.81 17.3 Stdev 0.19 4,083,158 4,798 62 2.11 0.90 0.29 0.83 0.81 0.28 0.28 1.2 Note: A denotes sampling location, B denotes percentage mycobacteria, C denotes pan bacterial count, D denotes genus count, E denotes conductivity (umhos/cm), F denotes DOC (mg/L), G denotes DO (mg/L), H denotes pH, I den otes total phosphorous (mg/L), J denotes dissolved phosphorous (mg/L), K denotes total nitrogen (mg/L), L denotes dissolved nitrogen, and M denotes temperature (C).

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100 Table 3 2. Comparison of estimated total bacterial and mycobacterial counts from aqui fer source water (pre treatment) and municipally distributed water (post treatment) from two municipal distribution systems. System treatment (chlor a mination) appears to uniformly reduce estimated counts for total bacteria, but not estimated counts for myc obacteria. Sample source Est. total bacterial count/mL Mean Est. Mycobacterial count/mL Mean Municipal 1 Pre treatment 562,534 711,726 2,604 2,960 860,918 3,316 Municipal 1 Post treatment 157,000 223,278 2,500 4,239 195,934 2,639 213,247 3,14 1 213,372 3,168 231,582 4,079 243,526 6,068 265,742 6,080 265,819 6,234 Municipal 2 Pre treatment 1,111,995 6,502,420 2,976 8,532 11,892, 845 14,088 Municipal 2 Post treatment 150,679 230,554 1,490 2,532 157,839 1,557 181,8 50 1,764 194,524 1,929 233,261 2,515 250,870 2,595 295,539 3,885 379,868 4,517

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101 Table 3 3 Range of environmental bacterial counts (total bacteria and mycobacteria) reported from previous studies. Reported Bacterial Grouping Estim ated CFUs Sample source Methodology Reference Heterotrophic bacterial plate counts 10 0 10 6 CFU/ mL Municipal Water Culture Payment et al., 1997 Heterotrophic bacterial plate counts 10 5 10 6 CFU/ mL Municipal Water Culture Norton et al., 2004 NTM 10 1 1 0 2 CFU/ mL Municipal Water Culture Falkingham et al., 2001 NTM 10 4 CFU/cm 2 Municipal Water, biofilm swabs Culture Falkingham, 2011 NTM 10 2 10 3 CFU/ mL Environmental Water qPCR Jacobs et al., 2009 MAC 10 1 10 3 CFU/ mL Municipal Water Culture Fattorini et a l., 2002 MAC 10 4 10 5 CFU/ mL Municipal Water Culture Norton et al., 2004 MAC 10 1 10 3 CFU/ mL Municipal and Environmental Waters Culture von Reyn et al., 1993 M. cheloneae, M. fortuitum 10 4 10 5 CFU/ mL Commercial distilled water Culture Carson et al., 1978 M. xenopi 10 1 10 5 CFU/ mL Municipal Water qPCR Hussein et al., 2009 Total Bacterial Count 10 5 cells/ mL Municipal Water qPCR Yarnell et al., 2011 NTM 10 3 cells/ mL Municipal Water qPCR Yarnell et al., 2011 MAC 10 0 10 2 cells/ mL Municipal Water qPC R Yarnell et al., 2011

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102 Figure 3 1 Estimated counts of total bacteria, mycobacteria, and MAC based on qPCR determination of number of DNA copies

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103 Figu re 3 2 Effect of pH on estimated bacteria counts for surface and municipal waters.

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104 CHAPTER 4 DEMOGRAPHICS OF NONTUBERCULOUS MYCOBACTERIA CASES IN FLORIDA, 2006 2008 Background Mycobacteria represent a highly diverse, species rich group of microorganisms within the genus Mycobacterium Although M. tuberculosis and M. leprae the causative agents of tuberculosis and leprosy, are obligate pathogens the vast majority of mycobacteria are free living environmental species that can be opportunistic pathogens and are known as nontuberculous mycobacteria (NTM). Over the past 20 years, the number of clini cal NTM isolates has exceeded that of tuberculosis isolates within the United States (US) (American Thoracic Society, 1997; Falkingham, 2002; Sood et al., 2007) NTMs, such as M. avium, M. kansasii, M. xenopi, M. scrofulaceum and M. marinum have been as sociated with pulmonary disease, bone and soft tissue disease, as well as disseminated diseases (Howard and Byrd, 2000; Vaerewijck et al., 2005) Disseminated infection with Mycobacterium avium complex (MAC) had been one of the most common bacterial oppor tunistic infection s in adults infected with HIV 1 in the developed world, and at one point was second only to AIDS Wasting Syndrome as the most common cause of death in those patients (Covert et al., 1999; Karakousis et al., 2004) With the availability o f highly active antiretroviral therapy, there has been a dramati c decline in mortality in the US HIV population due to NTM disease (Horsburgh, 1991; Aberg et al., 1998; Horsburgh et al., 2001; CDC, 2002). However, t he incidence of NTM infections appears to be increasing in otherwise healthy subjects (Moore, 1993; Griffith et al., 2007 ; Marras et al., 2007; Thomson, 2010 ) with the majority of clinical isolates associated with environmental sources (Fordham et al., 1993) The majority of these immunocompete nt persons also have

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105 underlying structural lung disease, such as bronchiectasis or COPD (Griffith et al., persons, that is persons with no known risk factors. T he p rimary mode s of transmission of NTMs to humans appears to be ingestion of water or inhalation of aerosols containing mycobacteria though more studies are needed to conclusively link the occurrence of NTM disease and these exposure routes (Falkingham, 1996 ; Primm et al., 2004; Feasel et al., 2009 ; Winthrop, 2010 ). Given the increasing prevalence of NTM infections, a growing population of susceptible, elderly and immunocompromised persons, there is a critical need to better understand the ecology of this gro up of pathogens, as this may help explain the environmental distribution, and thereby the transmission routes. There appears to be substantial regional variability in the number of reported NTM diseases across the US, with notably more NTM cases and highe r isolation prevalence being reported in persons residing in the Southeastern US, particularly along the Atlantic and Gulf coasts (Reed et al., 2006; Bilinger et al., 2009). Navy found that 60% of men from the Southeastern coastal regio ns of the US tested positive on Purified Protein Derivative Battery (PPD B) antigen tests, but showed no signs of disease (Edwards et al., 1969). To put that in context, only 2 7% of persons from the Northeast were found to react positively to MAC PPD B t ests (von Reyn et al., 1993). The PPD B test is used to discern skin reactivity to MAC antigens, and is used to detect antibodies present within a person associated with previous immunologic reaction. Thus, it was believed that these young men were expos ed and produced an immune response to mycobacterial antigens, namely MAC, but never developed outright disease (Edwards et al., 1969; von Reyn et al., 1993; Reed et al., 2006). The

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106 CDC reported that 41% of NTM isolates nationwide were from the Southeast U S ( Dobos et al., 1999). Further, previous studies have documented finding the highest numbers of M. avium complex organisms from brackish swamps and estuaries of the Southeastern coastal US ( Kirschner et al., 1992; Kirschner et al., 1999) The state of F lorida, in particular, was reported to have the highest rate of hospital admissions for NTM disease out of 11 states surveyed (Bilinger et al., 2009). Bilinger et al. (2009) also reported that prevalence of pulmonary NT M associated hospitalizations was in creasing in Florida for both men and women, a trend they noted only in Florida (Bilinger et al., 2009), though other studies have indicated similar trends elsewhere (Marras et al., 2007; Cassidy et al., 2009; Thomson, 2010). Based on this background, it i s relevant to gain an understanding of the epidemiology of NTM disease in Florida. This study evaluated hospital discharge data for trends in gender, race, age, seasonality, payer status, or associated co illness relative to NTM disease to determine any potential risk factors This study begins to unravel the epidemiology of NTM disease within the state of Florida, and will begin to provide linkages to ultimately discern NTM transmission and risk factors in future studies. Materials and Methods Data So urce De Administration (AHCA) database of hospital discharge diagnoses for all hospital admissions 2006 2008. The AHCA data base contains records of all hospital discharges within the stat e of Florida (Bean et al., 1992). Records containing an International Classification of Diseases, 9 th Revision, Clinical Modification code (ICD 9

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107 code) for NTMs (031.0, 031.1, 031.2, 031.8, and 031.9) were included in the initial screening. Due to low nu mbers of reported cases for the other NTM codes, only pulmonary NTM, 031.0, and disseminated NTM, 031.2, were included in the final analyses. The study population included all hospitalized persons within the state of Florida with either pulmonary or disse minated NTM disease listed as a primary or secondary discharge diagnosis. Data Analysis I describe NTM cases for year of hospitalization, zip code of home residence, quarter of the year when hospitalized, length of stay, age when hospitalized, sex, rac e, state of residence, payer status, and co illness ICD 9 codes associated with the hospitalized individual. Incidence s were determined by averaging the caseload across all three years (2006 2008), dividing by the state population estimate s for various ag e and racial categories ( US Census Bureau 2009 ; Florida Demographic Estimating Conference, 2010 ), and multiplying by 100,000. Statistical differences between pulmonary NTM disease observations and disseminated NTM disease observations were assessed for a ge, race, gender, and payer status, using a chi square test and linear regressions in SPSS ( IBM Corporation, Somers, NY ). P values of < 0.05 were considered statistically significant. Multivariate Analysis Variables of interest for the multivariate ana lysis were selected based on a review of the literature and prior clinical experience. The variables included in this study were demographic characteristics including age, gender, race, length of stay, payer status, year of hospitalization, quarter of the year hospitalized, as well as co illnesses including: HIV, anemia unspecified, candidiasis, cachexia, anemia of other chronic illness, atrial

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108 fibrillation, bronchiectasis without acute exacerbation, coronary atherosclerosis of the native coronary artery, obstructive chronic bronchitis with acute exacerbation, heart failure, acute respiratory failure, chronic airway obstruction not elsewhere classified, unspecified acquired hypothyroidism, nondependent tobacco use disorder, fever and other physiologic distu rbances of temperature, diarrhea, pancytopenia, acute kidney failure, esophageal reflux, and unspecified protein calorie malnutrition. The primary outcome of interest was hospitalization with pulmonary NTM disease as compared with all other forms of NTM d isease and likewise hospitalization with disseminated NTM disease as compared with all other forms of NTM disease. To determine significant, clinically relevant risk factors for hospitalization with either pulmonary or disseminated NTM disease, these outc omes were dichotomized and variables compared between the two outcomes. Factors with a P value <0.05 were considered significant. Adjusted odds ratios and corresponding 95% confidence intervals were calculated. Analyses were performed with SAS version 9.1.3 (SAS Institute Inc, Cary, NC). Results Demographic profiles for pulmonary and disseminated NTM were examined. This study attempted to examine key demographic components of NTM disease, including age, gender, race, quarter of the year hospitalized, payer status, length of stay, and associated co illnesses within hospitalized patients in the state of Florida. These were examined separately for both pulmonary and diss eminated NTM disease. It is my belief that these profiles may help to shed light on why these disease states appear to be increasing in Florida (Bilinger et al. 2009). Data from this study were categorically associated with either disseminated or pulmonary NTM disease based on observations through the SNTC (Michael Lauzardo, personal com munication) as well as previous

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109 studies suggesting that one type of NTM does not convert to the other. Our dataset does, however, include a limited number of persons (n=49, 0.96%) with both pulmonary and disseminated diseases. Our data set lacked signifi cant year to year variability ( 2 =3.25, df=2, P=0.20 ), and so our results were aggregated to show totals across all three years of the study. Pulmonary NTM A total of 2,535 cases of pulmonary NTM were reported in Florida through the ACHA database from 2 006 2008. I examined potential contribution of race, gender, age, quarter of year, payer status, length of hospitalization, and most common co illness from these cases. The racial distribution of NTM hospitalizations was examined for pulmonary NTM cases. White and Black/African Americans had significantly more cases, 70.85 and 19.21%, respectively than persons of other race s (Figure 4 1). Normalizing hospitalization incidences by race suggests differences between racial categories ( 2 =24.47, df=5, P <0.001 ), and indeed, incidence rates were 2 7 fold higher for whites and b lack/African Americans (Figure 4 2). Gender was found to differ statistically for normalized hospitalization incidence in older age groups ( 70yo) ( 2 =45.94, df=1, P<0.001) although the biological relevance of this difference across all age groups (47.81% male; 52.19% female ) is not clear Females make up the majority of cases (64.88%) in older ( 70yo) pulmonary NTM hospitalizations (Figure 4 3) and carry the highe st incidence rates, up to 22.11/100,000 population (Figure 4 4). Age distribution for pulmonary NTM cases was evaluated based on decadal age categories The distribution of normalized hospitalization incidence among age

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110 categories was not homogeneous ( 2 = 17180.54 df= 8, P <0.001 ), and was positively correlated with age (Pearson R=0.91, P=0.001). While both linear and exponential models demonstrated a correlation with increased age and pulmonary NTM caseload, the exponential model was a better fit (R 2 =0.9 6), suggesting an exponential increase of risk with age. The highest caseloads appeared in 70 year olds (44.14%; Figure 4 3), as did normalized hospitalization incidence ( 2 = 71.87 df= 1, P <0.001 ) with incidences as high as 19.59/100,000 for both sexes combined (Males ranged from 11.50 to 15.72/100,000; females ranged from 14.98 to 22.11/100,000 population) (Figure 4 4). Quarter of the year did not appear to influence the number of hospitalized cases reported, roughly 25% for each quarter Payer status: t he majority of patients were insured by Medicare, 57.84%, surpassing other methods of insur ance or no insurance ( 2 =3481, df=5, P <0.001 ) ( Figure 4 7 ). Average length of stay of the se patients was 11.25 days. My calculated statewide incidence rate of hospitalization of persons with pulmonary NTM disease was 4.41 per 100,000, but dramatic differences were noted in a ge adjusted categories, up to 22.11/100,000 population (Figure 4 4). Commonly associated co illnesses were primarily associated with underlying lung conditions, although other conditions were not uncommon (Table 4 1). To understand the contribution chroni c obstructive pulmonary disease (COPD) as a pre existing condition, data for obstructive chronic bronchitis with and without exacerbation (ICD 9 CM 491.21 and 491.22), emphysema not elsewhere classified (492.8), chronic obstructive asthma (493.20), and chr onic airway obstruction not elsewhere classified

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111 (496) were analyzed together. Overall, at least one of these conditions was p resent in 40.28% of pulmonary NTM cases. An additional 20.4% of patients had a personal history of tobacco use. Disseminated NTM A total of 2,326 cases of disseminated NTM were reported through the ACHA database from 2006 2008. I examined potential contribution of race, gender, age, quarter of year, payer status, length of hospitalization, and most common co illness from these cas es. The racial distribution of NTM hospitalizations was examined for disseminated NTM cases. White and b lack/African Americans had significantly more cases, 41.23 and 47.29%, respectively than persons of other race (Figure 4 1). Normalizing hospitalizati on incidences by race suggests differences between racial categories ( 2 =86.049, df=5, P <0.001 ) with b lack/African Americans carrying the highest incidence of all races, 12.47/100,000 population (Figure 4 2) Indeed, incidence r ates were 5 11 fold higher for b lack/African Americans (Figure 4 2 ). Gender was found to differ statistically for normalized hospitalization incidence in middle aged persons ( 30 49 year old ) ( 2 = 39.24, df=1, P<0.001) although the biological relevance of this difference across all age groups ( 52.41% male; 47.59% female) is not clear Males make up t he majority of cases ( 57.39%) in middle aged, disseminated NTM hospitalizations (Figure 4 5) and carry the highest incidence rates, up to 9.14/100,000 population (Figure 4 6). Age distribution for disseminated NTM cases was evaluated based on decadal age categories The distribution of normalized hospitalization incidence among age categories was not homogeneous ( 2 = 4246, df=8, P<0.001 ) Hospitalization caseload

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112 was relatively low for <20 year old patients ranging from ( 0.08 1.38% of cases; 0.03 0.69/100,000 population), while the majority of cases from other age groups ranged from 8.21 10.96% (Figure 4 5). The e xception was in the 30 49 year old groups which had a higher percentage of the total caseload, 23.52 25.32% (Figure 4 5), and represented the highest normalized incidence rates, 7.29 7.77/100,000 population ( 2 =45.10, df=1, P<0.001 ) (Figure 4 6 ). Within g ender adjusted categories, males aged 40 49 had the highest incidence noted, 9.14/100,000 population (Figure 4 6). Quarter of the year did not appear to influence the number of hospitalized cases reported, roughly 25% for each quarter Payer status: t he majority of patients were insured by either Medicare or Medicaid, 39.46% and 33.62%, respectively, surpassing other methods of insurance or no insurance ( 2 =1178.12, df=4, P <0.001) ( Figure 4 7 ). Average length of stay of these patients was 11.34 days. Our calculated incidence rate of hospitalization of persons with dissemin ated NTM was 4.03 per 100,000, though incidences as high as 9.14/100,000 populatio n were noted in age/sex adjusted populations (Figure 4 6). Commonly associated co illnesses were primarily associated with HIV/AIDS, however other co illnesses were not uncommon (Table 4 2). Discussio n Age Pulmonary NTM disease appears more common in the l ater decades of life consistent with data from other studies (Bilinger et al., 2009; Cassidy et al., 2009; Thomson, 2010) My study found the highest percentage of cases occurred in persons aged 70 79 (22.09%), but with similarly high rates in the 80+ gr ouping (22.05%). Age

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113 adjusted incidences were also found to be the highest in persons greater than 70 (19.59/100,000), consistent with data from other studies (Bilinger et al., 2009). This increased caseload in persons greater than 50 years of age sugges ts a disease process with an onset in the 5 th or 6 th decade of life. This may be due to some underlying genetic susceptibility or to the onset of underlying illness, such as COPD (Griffith et al., 2007). As NTM pulmonary disease is considered a chronic d isease (Griffith et al., 2007), the highest incidence in the elderly likely reflects the accumulation of old cases as well as new cases. For this reason, no further conclusions could be drawn regarding age of onset. Additionally, as persons are more like ly to be hospitalized later in the course of the disease, our data may be skewed toward an older population (Bilinger et al., 2009), and as our study was derived from hospitalized patients only, this potential bias can be difficult to rule out. Previous s tudies from outpatient data, however, have shown a similar trend toward the elderly, making this less likely (Prince et al., 1989; Huang et al., 1999; Kim et al., 2008). Further, Florida has long been associated with the number of retirees that choose the warmer climate in their later years, so the possibility exists that pulmonary NTM is more common in the elderly due to immigration of retirees from other areas. This is unlikely the sole reason for the noted increases in Florida as young naval recruits f rom the southeast were found to have a higher prevalence of NTM exposures as measured by skin hypersensitivity reactions to purified protein derivative (PPD B), as well as multiple studies linking the southeast to higher exposure rates ( Smith, 1967; Edward s and Smith, 1969; Dobos et al., 1999 ; Reed et al., 2006; Bilinger et al., 2009).

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114 Conversely, disseminated NTM disease appears to be more common in the m iddle years of life, ages 30 49, and age adjusted incidence rates over this range were similarly foun d to be highest. Disseminated NTM is closely linked to immunocompromised states including those persons on long term steroid therapy or, most notably, those persons living with HIV (Horsburgh et al., 1985). In HIV negative persons, disseminated NTM is pr imarily linked to defects in cellular immunity, while in the HIV population it is linked to CD4 counts of less than 75 100/mm 3 (Nightingale et al., 1992). Given that the highest numbers of both new cases of HIV/AIDS and the highest number of cumulative ca ses of HIV/AIDS occur in persons aged 35 44 and 30 44 respectively (CDC, 2006), it follows that disseminated NTM w ould also follow this trend. I believe the younger distribution of disseminated cases of NTM to be correlated with the younger pool of suscep tible persons, particularly the HIV infected population. Gender Gender was statistically different in pulmonary NTM disease associated hospitalized patients. Older studies from the 1970s 1980s historically documented a 1987). Recent studies including both hospitalized discharge data and single site studies, however, have reported a female predominance for pulmonary NTM disease (Prince et al., 1989; Kennedy et al., 1994; Huang et al., 1999; Kim et al., 2008; Bilinger e t al., 2009). Our study found a modest female predominance, 52.19%, within pulmonary NTM cases. Thus, our finding does follow previously reported trends, but the degree of female predominance was not strong enough to draw any definitive conclusions. Loo king at age adjusted figures, however, females over the age of 70 were found to have the highest incidence of all age/sex categories examined, up to 22.11/100,000. It is still unclear at this time if pulmonary

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115 NTM disease predominates in more recent clini cal studies because women outnumber men in the older age groups or if this modest increase in females may be linked to a bias inherent to the data. AHCA data, for example, does not include VA hospitals, and so may be missing large numbers of male subjects particularly elderly males. Further, a large proportion of patients had COPD as an associated diagnosis (40.3%) and an additional percentage (20.4%) used tobacco products. Since males predominated in the earliest studies of NTM and the majority of these had COPD, it is possible that the risk of hospitalization with NTM is increased for men because of an increased incidence of COPD and the associated increased risk of hospitalization (Timpe and Runyon, 1981). Gender was significantly different in dissemi nated NTM disease in th e middle years of life (30 49 year olds ). My study found that 52.41% of patients hospitalized with disseminated NTM were male, but 57 % were male in the middle aged groups. As the highest normalized incidence was found in persons in the middle years of life and the majority of HIV infected persons are in the middle years of life ( CDC, 2006 ), I expected gender would follow HIV status, and, indeed, the majority of per sons infected with HIV are male (CDC, 2006). Thus, I believe HIV sta tus may be governing this trend. Race Pulmonary NTM disease is more common in persons identified as w hite and disseminated NTM is more common in b lack/ African Americans. Studies have long suggested that NTM disease is increasing in otherwise healthy per sons, especially elderly, w hite females (Moore, 1 993; Griffith et al., 2007). I found persons hospitalized with pulmonary NTM within the state of Florida to be white 70.85% of the time, thus supporting these observations although normalized yearly incide nce implied a higher risk for b lack/African Americans than whites Disseminated NTM had a more even

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116 mixture between b lack/ African Americans (47.29%) and white persons (41.23%) but normalized incidence ra tes show an increased risk for b lack/African Americ ans (12.47/100,000 population) As HIV incidence rates for African Americans are 6 7 times higher than for whites, the African American predominance was not unexpected (CDC, 2006; Hall et al., 2008). It has previously been hypothesized that African Americ ans are at an increased risk of tuberculosis (Stead et al., 1985) and here I demonstrate increas ed risk for both NTM states in b lack/African Americans, suggesting there may be some underlying genetic susceptibility within African Americans to mycobacterial disease. Further, the concentration within these two races, white and black, implies a possible genetic contribution to susceptibility, but as regional variability is also reported (Kirschner et al., 1992; Kirschner et al., 1999; Dobos et al., 1999; Bili nger et al., 2009) it is likely that NTM disease has both a genetic and ecological component. Seasonality Quarter of the year was monitored as a marker for seasonality. NTM related diseases were reported to be higher in the southeastern United States ( Edwards et al., 1969; Reed et al., 2006), and it has been hypothesized that the higher average temperature and humidity in these areas may favor mycobacterial growth and/or survival within aerosol droplets (Bilinger et al., 2009). These conditions imply t hat exposure should be roughly year round and so no major difference was expected between quarte rs (von Reyn et al., 2001). My results demonstrate that NTM caseloads are similar year round, roughly 25% of the caseload per quarter. These data support the theory that year round exposure may be correct (von Reyn et al., 2001). It does not, however, dismiss the notion that hospitalizations are similar throughout the year, but the timing of exposure(s) may be independent.

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117 Payer S tatus Payer status was anal yzed as a marker for socioeconomic status. In both pulmonary (16.13%) and disseminated (15.00%) NTM diseases, only a small subset of the population carried commercial health insurance. The vast majority of persons relied on government issued insurance su ch as Medicare and Medicaid. Persons with pulmonary NTM primarily paid with Medicare (57.84%), whereas most persons with disseminated NTM paid with either Medicare (39.46%) or Medicaid (33.62%) ( Figure 7 ). Medicare is a program designed to provide health coverage for the individuals aged 65+ years of age, and so the increased number of persons with pulmonary NTM paying with Medicare was not unexpected as the majority of persons with pulmonary NTM are of advanced age. The younger demographics associated w ith disseminated NTM may explain why fewer persons paid with Medicare, and why there were more Medicaid claims for disseminated NTM patients compared with pulmonary NTM patients. Interestingly 39.46% of patients with disseminated NTM disease paid with Med icare while only 27.82% were over the age of 60. This implies that a portion of persons with disseminated NTM disease are qualifying for Medicare for reasons other than age. Ultimately, the majority of persons hospitalized with NTM disease rely on governm ent insurance programs. Length of S tay were. There was no difference between length of stay for pulmonary versus disseminated NTM disease patients (11.25 vs 11.34 day s, Z= 0.006, P =0.50). Based on previous studies (DeFrances et al., 2003), however, patients admitted for either pulmonary NTM or disseminated NTM stayed on average twice as long as patients

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118 admitted for any reason (4.8 days) or for an infectious disease (6 .4 days). This suggests that persons admitted with an NTM disease are likely to be much sicker than the average person admitted for any cause or admitted for infectious diseases. As the admitted time was extended for both pulmonary and disseminated NTM, which have different age distributions, it is not believed that this finding is based solely on age, and may instead be related to the immunocompromised state of individuals infected with NTM disease. The immune system often fails in the elderly leading t o immunocompromised states (Kendall et al., 2003), and persons with disseminated NTM are likely to have HIV or some other underlying immunocompromised state (Howard and Byrd, 2000; Falkingham, 2003). Thus, it is likely the extended hospital stays reflect that NTM patients are often far sicker than average, as many are immunocompromised. Co illness es Heart disease and COPD were the most commonly associated co illnesses with pulmonary NTM. Analysis of the most common ICD 9 codes associated with pulmonary NTM revealed that most patients had underlying heart or lung disease. A previous study similarly found underlying heart and lung disease to be the most commonly associated co illnesses with pulmonary NTM (Bilinger et al., 2009). Combining percentages fr om the underlying heart conditions such as hypertension, atrial fibrillation, atherosclerosis of the coronary artery, and heart failure we found that 72.97% of patients admitted with pulmonary NTM had underlying heart disease. It is not clear at this time if the correlation of pulmonary NTM and heart disease is additive, as it seems more likely that the heart disease component is explained by the increased age of persons admitted with pulmonary NTM, as heart diseases are more common in the elderly (Kannel et al., 1998). Underlying lung disease was also common in patients

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119 admitted for pulmonary NTM. Bronchiectasis and other underlying structural damage (COPD) have long been linked to pulmonary NTM disease (Griffith et al., 2007), and were both found as com mon co illnesses in previous studies of pulmonary NTM disease (Bilinger et al., 2009). Similarly, we found bronchiectasis in over 14.79% and COPD in 40.28% of persons admitted for pulmonary NTM. Pneumonia was previously reported as the most common reason for admission (Bilinger et al., 2009), and we found pneumonia in 24.97% of our patients, thereby supporting this as a common co illness in these patients. Taken together, underlying heart and lung disease appear to be common co illnesses to pulmonary NTM. It is possible these co morbidities may drive physicians to hospitalize these patients, and so may be over inflated in our hospitalized population, as well as skewing towards an elderly population base. The lack of one predominant co illness is not insi gnificant, as it supports the possibility that NTM disease is caused by diverse etiologies, and is consistent with single site studies suggesting an increasing proportion of cases with no known risk factors (Prince et al., 1989; Kennedy et al., 1994; Huang et al., 1999; Kim et al., 2008). Disseminated NTM was closely linked to HIV. Persons with immune compromising conditions have the greatest risk of contracting disseminated NTM with AIDS carrying the worst prognosis in these patients (Howard and Byrd, 200 0; Falkingham, 2003). NTM disease often begins to manifest in AIDS patients when CD4 counts drop below 100/mm 3 with NTM organisms often isolated from the blood, tissue, sputum, and fecal material of these patients (Nightingale et al., 1992; Falkingham 200 3). My study found 65.56% of persons with disseminated NTM were co infected with HIV. Given the decline in both overall health as well as immune failures associated with HIV/AIDS,

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120 especially late stage AIDS (Horsburgh, 1991; Karakousis et al., 2004), it w as unsurprising to find opportunistic diseases and other diseases associated with general poor health such as candidiasis, diarrhea, cachexia, and dehydration were among the most commonly reported co illnesses in this study. Other associated co illnesses, such as anemia (41.79%), electrolyte imbalances (32.94%), and malnutrition (10.45%), are likely to be related to the overall decline. Each of these disease states are too general to make any concrete conclusions, but taken together, it seems that the co illnesses associated with disseminated NTM are largely driven by the HIV positive status of most disseminated NTM patients. Several disease states were common to both pulmonary and disseminated NTM. Hypertension, anemia, HIV, pneumonia, chronic airway ob struction, tobacco use, esophageal reflux, hypoosmolality and/or hyponatremia, hypopotassemia, cachexia, dehydration, protein calorie malnutrition, and candidiasis were common to both pulmonary and disseminated NTM. The presence of hypertension may be exp lained by the high prevalence rate within the US population, but this does not hold true for the other co illnesses common to both NTM diseases. Wasting syndromes have long been associated with AIDS, but in the last decade a growing number of studies have reported pulmonary disease in elderly, thin, white, women (Griffith et al., 2007). It is possible then that being underweight lends some increased risk for the acquisition of NTM disease. It is unlikely that weight loss itself would have this effect, bu t cachexia may help explain some of the other states, such as malnourishment, dehydration, and electrolyte imbalances, which may contribute to increased susceptibility.

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121 Anemia has previously been reported in both disseminated and pulmonary NTM patients ( Havlik et al., 1992; Field and Cowie, 2006; Bi linger et al., 2009), but to my knowledge this is the first study reporting this in both disease s tates together. Given this long standing trend, confirmed in the present study, anemia may be a risk factor for all NTM diseases. Esophageal reflux was found to be common to both NTM diseases in this study. Anectodal reports suggest that persons taking proton pump inhibitors are at increased risk of pulmonary NTM disease (David Ashkin, AG Holly Tuberculosis Hospi tal, personal communication ). Possible rationale associating reflux disease with NTM disease may include aspiration of regurgitated stomach contents or through irritations in the esophageal lining. Pneumonia, chronic airway obstruction, and tobacco use have long been documented risk factors for pulmonary NTM disease (Griffith et al., 2007), but it has long been suggested that persons with disseminated NTM did not show lung manifestations (Field and Cowie, 2006). Given these were commo n in both NTM disea se states, I question the validity of observations suggesting persons with disseminated NTM do not show signs of pulmonary disease. Finally, HIV is common to both pulmonary and disseminated NTM. HIV is commonly associated with disseminated NTM, as descr ibed above, but it is far less commonly studied in the co ntext of pulmonary disease. My finding that over 20% of persons with pulmonary NTM also have HIV supports the idea that this group of persons, those co infected with pulmonary NTM and HIV, are an un derstudied group of clinical importance.

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122 Incidence Incidence rates for persons hospitalized with pulmonary NTM appears higher than previously reported. Previously, non AIDS related mycobacterial diseases was estimated to infect around 1.8 out of 100,000 et al., 1987). S tatewide incidence of NTM infection, however, cannot be reasonably estimated based on nationwide data since there appear to be regions where differences in health status (e.g., HIV status, nutriti onal status) may increase susceptibility to disease ( Pradhan et al., 2003; Deaton, 2008 ; Tan et al., 2010 ) Also, substantial regional variation in reported infections with different NTM organisms (i.e., MAC, M. scrofulaceum etc.) makes geographic genera lization problematic ( Marion et al., 2010 ; Tan et al., 2010 ) To help address these discrepancies a follo w up study by Bilinger et al. (2009) focused on regional incidence rates for 11 individual states. The average incidence in Florida was 2.1 hospita lizations per 100,000 persons for pulmonary NTM in 1998, increasing to 2.4 hospitalizations in 2005 the highest for all states observed Incidence of hospitalizations per 100,000 persons for pulmonary NTM from the present study (2006 2008) was 4.41, 1.8 fold higher compared with 2005 Florida data from the Bilinger et al. (2009) study Incidence rates of hospitalization for disseminated NTM were also found to be high in my study with a statewide incidence of 4.03 per 100,000 hospitalizations. As my rate s are not uniform across the state, there are likely some external factors controlling distributions of NTMs within the state and will be explored further in a follow up study. Multiple hospitalizations for a patient in a given year in the present study cannot be ruled out, based on the de identified data that was analyzed. Therefore, data reported

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123 in this study may slightly overestimate incidence if patients were admitted multiple times for the same disease in a given year. Nevertheless, the present stu dy does represent data from a hospitalized population It is important to note that most pulmonary NTM diseases are diagnosed and managed in an outpatient setting, not in hospitals, with approximately 10:1 ratio of outpatient to inpatient NTM cases (Micha el Lauzardo and Kevin Fennelly, SNTC personal communication ). Therefore, this study likely grossly underestimate s the actual caseload of NTM disease in the state of Florida some ten fold higher than hospitalized inciden ce This may be particularly true of children with Cystic Fibrosis (CF), a known risk factor of NTM disease (Griffith et al., 2007), as they are likely managed in an outpatient setting. Additionally, the use of outpatient data might allow for inclusion of other mycobacterial diseases such as cutaneous manifestations, which are believed to be the most common NTM manifestation (Griffi th et al., 2007). Without a database of outpatient diagnoses, such a study would be extremely difficult at this time, as th ese are not reportable diseases and rarely report for inpatient treatment. Additionally, the validity of IDC 9 codes for reporting NTM diseases is unclear, and therefore may underrepresent hospitalization incidence since these diseases are rarely observed in hospital evaluations (Bilinger et al., 2009). Multivariate Analysis With the multivariate analysis 11 factors were found to be risk factors for hospitalization with pulmonary NTM disease (age, payer status, HIV, candidiasis, bronchiectasis, bronchitis respiratory failure, tobacco use, fever, pancytopenia, and chronic airway obstruction) and 5 factors were risk factors for hospitalization with

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124 disseminated NTM disease (payer status, HIV, cachexia, fever, and pancytopenia) (Table 4 3). This study had s ignificant limitations as we only had information on persons hospitalized with NTM disease and not information on all hospitalized persons. However, The data revealed some interesting results. The results of the multivariate analysis demonstrated that age increases the odds of hospitalization with pulmonary NTM disease, but only to a small effect. Payer status is significant. The lack of a diagnosis of HIV, fever, and pancytopenia increases your chances of being hospitalized with pulmonary NTM disease as compared with other NTM diseases while a lack of candidiasis, bronchiectasis, bronchitis, respiratory failure, chronic airway obstruction, and a history of tobacco use may be protective against hospitalization for pulmonary NTM as opposed to other NTM dis eases. This suggests these predisposing lung conditions may increase your chances of developing pulmonary NTM disease and is consistent with previous clinical observations (Griffith et al., 2007). Similarly, the payer status was significant for hospitali zation with disseminated NTM over other NTM disease while a lack of conditions such as HIV, cachexia, fever, and pancytopenia may be protective against hospitalization with disseminated NTM disease. Again, this suggests that having these conditions would likely increase your chances of developing disseminated NTM disease. Though limited, this study begins to tease out the important risk factors differentiating between hospitalization with pulmonary and disseminated NTM disease within the state of Florida. Final Thoughts In summary, NTM cases are likely increasing within the United States and in particular, Florida (Bilinger et al., 2009). The present study suggests that s tatewide

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125 incidence for pulmonary (4.41/100,000) and for disseminated (4.03/100,000 ) NTM disease s in Florida was over 1. 8 fold higher than previously reported (2.4/1 00,000; Bilinger et al., 2009). This study documented the demographic profile of persons hospitalized with NTM disease in Florida. This study demonstrated that hospitaliza tions with p ulmonary NTM disease were more common in elderly ( 70 year old) w hite females, whereas hospitalizations with disseminated NTM disease were more common in middle age ( 30 49 year old ) white and b lack/African American males Normalized incidence data for both diseases, however, i mplies that race, specifically b lack/African American, is a risk factor. The most common co illnesses associated with pulmonary NTM disease related to either underlying heart or lung conditions. The most common co illnes ses associated with disseminated NTM disease appear to be driven primarily by health status associated with HIV infection. Coverage of hospitalizations for both diseases was primarily through government based programs, Medicare and Medicaid, and length of stay was longer than hospitalizations associated with other infectious diseases or any other reason.

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126 Table 4 1. Co HealthCare Administration (AHCA) database of hospital discharge diagnoses, 2006 2008. ICD 9 Code Description Percentage of c ases with co reported illness 401.9 Unspecified essential hypertension 32.58 486 Pneumonia organism unspecified 24.97 42 Human immunodeficiency virus (HIV) 20.63 285.9 Anemia unspecified 19. 57 496 Chronic airway obstruction not elsewhere classified 17.48 305.1 Nondependent tobacco use disorder 17.04 530.81 Esophageal reflux 15.66 427.31 Atrial fibrillation 14.83 494 Bronchiectasis without acute exacerbation 14.79 414.01 Coronary atheros clerosis of native coronary artery 14.16 272.4 Other and unspecified hyperlipidemia 14.12 491.21 Obstructive chronic bronchitis with (acute) exacerbation 14.00 276.1 Hyposmolality and/or hyponatremia 13.69 276.8 Hypopotassemia 12.35 276.51 Dehydration 11.76 428 Heart failure 11.40 518.81 Acute respiratory failure 11.28 799.4 Cachexia 11.16 244.9 Unspecified acquired hypothyroidism 10.89 263.9 Unspecified protein calorie malnutrition 10.77 285.29 Anemia of other chronic illness 10.57 112 Candidia sis 10.22

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127 Table 4 2. Co for HealthCare Administration (AHCA) database of hospital discharge diagnoses, 2006 2008. ICD 9 Code Description Percentage of cases with co reported illnes s 42 Human immunodeficiency virus (HIV) 65.56 285.9 Anemia unspecified 23.13 112 Candidiasis of mouth 19.78 799.4 Cachexia 19.65 285.29 Anemia of other chronic illness 18.66 486 Pneumonia organism unspecified 18.40 401.9 Unspecified essential hyper tension 18.27 276.8 Hypopotassemia 17.89 305.1 Nondependent tobacco use disorder 17.46 276.51 Dehydration 15.56 276.1 Hyposmolality and/or hyponatremia 15.05 780.6 Fever and other physiologic disturbances of temperature regulation 13.03 787.91 Diarrh ea 12.94 284.1 Pancytopenia 12.21 584.9 Acute kidney failure, unspecified 11.13 530.81 Esophageal reflux 10.58 263.9 Unspecified protein calorie malnutrition 10.45 496 Chronic airway obstruction not elsewhere classified 10.06

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128 Table 4 3. Significan t results of the multivariate analysis. Variable Chi Square P value Odds Ratio 95% Confidence Limit Pulmonary NTM Disease Age 112.8132 <0.0001 1.025 1.02 1.03 Payer Status 37.0119 0.0007 0.14 0.039 0.560 HIV 80.0749 <0.0001 2.481 2.033 3.027 Candidias is 4.1407 0.0419 0.823 0.682 0.993 Bronchiectasis 21.1161 <0.0001 0.627 0.513 0.765 Bronchitis 5.037 0 0.0248 0.799 0.657 0.972 Respiratory Failure 4.7863 0.0287 0.792 0.643 0.976 Tobacco use 15.1422 <0.0001 0.727 0.619 0.853 Fever 8.2495 0.0041 1.396 1.112 1.752 Pancytopenia 7.3785 0.0066 1.447 1.108 1.890 Chronic Airway Obstruction 4.5173 0.0336 0.83 0 0.699 0.986 Disseminated NTM Disease Payer Status 28.2359 0.0132 2.98 0.599 14.622 HIV 408.2841 <0.0001 0.115 0.093 0.141 Cachexia 6.2671 0. 0123 0.793 0.661 0.951 Fever 4.0926 0.0431 0.809 0.658 0.993 Pancytopenia 13.5337 0.0002 0.617 0.477 0.798

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129 Figure 4 1. Racial distribution of p ulmonary versus disseminated NTM hospitalizations White persons predominate in pulmonary NTM while both white and African American persons contribute significantly to disseminated NTM caseloads. of hospital discharge diagnoses, 2006 2008.

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130 Figure 4 2 Racial distribution of p ulmon ary versus disseminated NTM normalized yearly incidence rates African Americans and Whites have elevated risk in pulmonary NTM disease and African Americans are at increased risk of disseminated NTM disease. Adm inistration (AHCA) database of hospital discharge diagnoses, 2006 2008.

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131 Figure 4 3 Age and gender distributions of p ulmonary NTM cases based on Agency for Health Care Administration (AHCA) database of hospital discharge diagnoses, 2006 2008. Pulmonary NTM cases appear to increase with age (P<0.001).

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132 Figure 4 4 Normalized yearly incidence distributions broken down by age and gender for p ulmonary NTM disease based on Administration (AHCA) database of hos pital discharge diagnoses, 2006 2008. Pulmonary NTM disease risk increases with age (P= 0.001 ) with the highest risk in elderly females (P <0.001 ).

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133 Figure 4 5 Age and gender distributions of disseminated NTM cases based on are Administration (AHCA) database of hospital discharge diagnoses, 2006 2008. D isseminated NTM disease caseload appears highest in middle age persons, 30 49 years old (P <0.001)

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134 Figure 4 6 Normalized yearly incidence distributions broken down by ag e and gender for disseminated NTM disease based on Administration (AHCA) database of hospital discharge diagnoses, 2006 2008. D isseminated NTM disease risk appears highest in middle age persons, 30 49 years old (P <0.001) particularly males (P <0.001 ).

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135 Figur e 4 7 P ayer status for patients hospitalized with either pulmonary or disseminated NTM disease based on (AHCA) database of hospital discharge diagnoses, 2006 2008. T he majority of persons admitted with pulmonary NTM paid with Medicare, whereas the majority of persons admitted with disseminated NTM paid with either Medicare or Medicaid.

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136 CHAPTER 5 SPATIO TEMPORAL PATTERNS OF REPORTED NONTUBERCUL OUS MYCOBACTERIA CASES IN FLORIDA, 2006 2008 Background Overview T he genus Mycobacterium represent s a highly diverse, species rich group of microorganisms. Although best known as obligate pathogens and the causative agents of tuberculosis and leprosy, the vast majority of mycoba cteria are free living environmental species known as nontuberculous mycobacteria (NTM), which can be opportunistic pathogens ( Vaerewijck et al., 2005 ) Over the past 20 years, the number of clinical NTM isolates has exceeded that of tuberculosis isolate s within the United States (US) (American Thoracic Society, 1997; Falkingham, 2002; Sood et al., 2007) NTMs such as M. avium, M. kansasii, M. xenopi, M. scrofulaceum and M. marinum have been associated with pulmonary disease, bone and soft tissue disease and disseminated diseases (Howard and Byrd, 2000; Vaerewijck et al., 2005) Indeed, d isseminated infection with Mycobacterium avium complex (MAC) was one of the most common bacterial opportunistic infection s in HIV 1 infected adults in the developed wor ld, and at one point was second only to AIDS Wasting Syndrome as the most common cause of death in such patients (Covert et al., 1999; Karakousis et al., 2004) The advent of highly active antiretroviral therapy (HAART) has led to a dramatic decline in mo rtality attributable to NTM disease among HIV infected individuals in the US (Horsburgh, 1991; Aberg et al., 1998; Horsburgh et al., 2001; CDC, 2002). The incidence of NTM infections appears to be increasing among otherwise healthy subjects (Moore, 1993; G riffith et al., 2007 ; Marras et al., 2007; Thomson, 2010 ) But since most of these immunocompetent persons also have underlying

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137 structural lung disease such as bronchiectasis or COPD (Griffith et al., 2007), it remains to be seen if disease prevalence is t known risk factors. Most clinical NTM isolates are associated with environmental sources (Fordham et al., 1993) T he primary mode s of transmission NTMs to humans appears to be ingestion of water or inhala tion of aerosols containing mycobacteria though more studies are needed to conclusively link these exposure routes to the occurrence of NTM disease (Falkingham, 1996; Primm et al., 2004; Feasel et al., 2009 ; Winthrop, 2010 ). Given the increasing prevalenc e of NTM infections, a growing population of susceptible, elderly and immunocompromised persons, there is a critical need to better understand the ecology of this group of pathogens, as this may help explain the environmental distribution, and, in turn, th e transmission routes. Immunologic, epidemiologic and environmental microbiology studies together suggest that the southeastern US may have higher NTM exposure risk compared with other parts of the country (Falkingham, 1996; Dobos et al., 1999; Reed et al ., 2006), but do not provide the basis for definitive conclusions. Nevertheless, this literature sets the stage for questions about risk factors in the Southeast. Clinical NTM cases have a particularly high prevalence along the Atlantic and Gulf coasts co mpared with other parts of the country (Reed et al., 2006; Bilinger et al., 2009). Purified Protein Derivative Battery (PPD B) antigen tests used by the Navy in the 1960s revealed that 60% of men from the southeastern coastal regions of the US tested posit ive for MAC exposure (Edwards et al., 1969), compared with 2 7% in men in the

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138 Northeast (von Reyn et al., 1993). Further, the majority (41%) of diagnostic laboratory NTM isolates nationwide were from the Southeast US ( Dobos et al., 1999). The state of F lorida, in particular, has higher NTM related hospital admissions compared with other parts of the country, and hospital admissions continue to increase (Bilinger et al., 2009). That might be attributable to prevailing environmental conditions such as fres h waters rich in humic and fulvic acids, and brackish coastal swamps and estuaries, which appear to foster the growth of NTMs and MAC ( Kopecky 1977; Kazda et al., 1990; Kirschner et al., 1992; Johnson Ifearulundu and Kaneene 1997; Kirschner et al., 1999 ; Reviriego et al., 2000 ) Nonetheless, other geographic regions with differing environmental conditions, such as Ontario, Canada (Marras et al., 2007), Oregon (Cassidy et al., 2009) and Queensland, Australia (Thomson, 2010). also have seen increasing numbe rs of cases. Geospatial Analysis T he ability to discern the distribution and e pidemiology of NTM disease is critical, given the increasing numbers of cases in various regions (Marras et al., 2007; Bilinger et al., 2009; Cassidy et al., 2009) Spatial st atistics and geographic information systems (GIS) were used in this study to assess regional patterns of NTM related hospitalization Blackburn (2010) provided a framework for employing Exploratory Spatial Data Analysis (ESDA) to evaluate spatial patterns of disease case data. ESDA is a set of tools to describe and visualize spatial distributions, identify atypical localizations, detect spatial associations such as hot or cold spots, and suggest spatial heterogeneity (Haining, 1990; Bailey and Gatrell, 1995 ; Anselin, 1998; Anselin, 1998). S patial autocorrelation an important ESDA, is used to discern coincidence of value simil arity with locational similarities (Anselin, 2000). Tests of spatial

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139 autocorrelation are inferential and used to identify spatial p atterns. For example, a p ositive spatial correlation occurs when high or low values for a given variable cluster in space Likewise, a negative spatial correlation occurs when a geographical area is surrounded by neighbors with dissimilar values. Patter ns that exhibit neither positive nor negative autocorrelation can be defined as spatially random. Spatial autocorrelation analyses can be global, aimed at determining if spatial dependence is present across a study region; or local, identifying where on th e landscape spatial dependence occurs (Anselin, 1995). L ocal spatial autocorrelation s can be discerned using local indicator s of spatial association LISA (Anselin, 1995), which evaluates the spatial relationship between attribute values of a local geogra phic unit (e.g., county, zip code, etc.) with those of its neighboring units in a hypothesis testing framework that compares local observations against a spatially random distribution. Anselin (1995) introduced the local of each aerial unit to the global measure, identifying where on the landscape patterns of autocorrelation are occurring. While NTM disease affects both humans and animals, its ecology is complex and i ts distribution remains poorly understood (Pedley et al., 2004; Vaerewijck et al., 2005; Winthrop 2010). A number of studies have evaluated the physiological niche of these organisms within the environment (Edwards et al 1969; von Reyn et al., 2001; Re ed et al., 2006; Sood et al., 2007; Langevin et al., 2008; Winthrop 2010 ) but few have addressed the geographical distribution of infections or the distribution of environmental parameters that may promote mycobacter ial growth (Bloch et al., 1998; Claudi a et al., 2004; Duker et al., 2004; Judge et al., 2005; Chan Yeung et al., 2005; Rushton et al.,

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140 2007; Jacobs et al., 2009; Charti and Kazemnegad, 2010 ). Other studies focusing on the geographical distribution of M. tuberculosis or M. leprae caseloads (e. g., Claudia et al., 2004; Chan Yeung et al., 2005; Charti and Kazemnegad, 2010), do not aid discerning of patterns for NTM, because those organisms are not environmental, and they have very different modes of transmission ( Vaerewijck et al., 2005 ). Geosp atial studies of NTMs, while limited, give interesting results. Environmental studies suggest that NTMs may be influenced by arsenic levels in soils (Duker et al., 2004), water chemistry conditions (Jacobs et al., 2009), and host species habitat (Judge et al., 2007). Human NTM diseases have been associated with areas of poverty and high HIV prevalence (Bloch et al., 1998), and general health deprivation (Rushton et al., 2007). Extensive efforts are clearly warranted to provide a better understanding of e nvironmental risk factors associated with NTM disease. Thus, the purpose of th e current study was to : 1) e valuate the spatial distribution of NTM hospitalization incidence in Florida across a three year period for pulmonary and disseminated cases in both HIV positive and HIV negative persons, and 2) e mploy LISA to test for spatial autocorrelation of NTM cases of each group in the state. This is the first study to examine the geographical distribution of NTM disease in Florida using geospatial modeling te chniques. These efforts are aimed at identifying local hotspots of cases that may inform hypotheses on NTM transmission and risk factors for future studies. Materials and Methods Data Source De identified data were provided by the Florida Agency for He alth Care Administration (AHCA) database of hospital discharge diagnoses from 2006 2008

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141 (Bean et al., 1992). Records containing an International Classification of Diseases, 9 th Revision, Clinical Modification code (ICD 9 code) for NTMs (031.0, 031.1, 031. 2, 031.8, and 031.9) were included in the initial screening. O nly pulmonary NTM, 031.0, and disseminated NTM, 031.2, were included in the final analyses because of low numbe rs of reported cases for other NTM codes. The study population included all hospit alized persons within the state of Florida with either pulmonary or disseminated NTM disease listed as a primary or secondary discharge diagnosis. Data Analysis A queryable database was constructed and linked to a zip code data layer in a GIS. To estim ate annual zip code level incidence, case counts were identified to the zip code by year divided by US C ensus Bureau population estimate s for 2008 ( US Census Bureau 2008 ) then multiplied by 100,000. Population estimates for 2008 were available for most zip codes, and when they were not, federal estimates for 2005 ( US Census Bureau 2005) were used. Incidence of NTM related hospitalizations was determined using the field calculator within ArcGIS software (ESRI, Redlands, CA), and subsequently mapped usi ng ArcGIS software to the zip code level. A guide map was created to visualize major roadways, cities and waterways (Figure 5 1). Confidentiality Confidentiality was maintained through HIPPA standards and approved protocols reviewed by the University o f Florida Institutional Review Board (IRB). Data from any zip codes with fewer than 20,000 persons were masked (Leitner and Curtis, 2006). It was determined that 273/946 zip codes ( 29%) required masking One method is to dissolve (i.e., adjoin) zip codes with neighboring zip codes to form larger units with > 20,000 persons (Curtis et al., 2011). Since t he primary focus of this project was to use

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142 local measures of autocorrelation to evaluate local (zip code level) spatial patterns and identify hot spots o f NTM hospitalizations (Anselin, 1995 ) such modifications in spatial aggregation would greatly affect the outcome of the analyses ( Grubesic, 2008 ). Instead, a spatial masking strategy was employed that preserved approximate spatial relationships while re moving specific identifiers of a zip code suc h as exact shape and size, through the use of a Thiessen polygon surface (Curtis and Leitner, 2006; Curtis et al., 2007). This method works b y assigning a centroid (center point of the spatial unit) to the geog raphic center of the zip code in a GIS layer, creating a series of vertices at the midpoint of any two points in the distribution, and connecting those vertices to create unrecognizable polygons in the approximate location of the zip codes (Brassel and Rei f, 1979; Anselin et al., 2006). To prevent re engineering of specific zip codes (Curtis et al., 2006; Brownstein et al., 2006; Curtis et al., 2011 ), an additional layer of masking was needed. A stratified random sampling approach was used to generate a r andomly located point within each zip code to replace the true centroid (Epstein et al., 2002) T hese points do not directly correspond to the center of a zip code boundary, but may lie anywhere within the zip code. Thiessen polygon boundaries were then drawn around the new, masked points using the Proximity tool in ArcGIS Toolbox 9.3.1 Thus, this polygon surface maintain ed the spatial patterns of the zip code data with relative polygon locations, but the loc ations were not directly linked to the actual zip code of reporting. Figure 5 1 illustrates the Thiessen polygon surface and references several landmarks used to describe cluster patterns.

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143 Smoothing Data sets for many diseases are based on relatively low case numbers and variable population data a cross a study area ( Beroll et al. 2007 ), and accommodations must be made for this. Bayesian methods have been employed to reduce the heterogeneity in variance associated with disease reporting data prior to performing hypothesis test based analyses ( Happo ld et al. 2008; Chen et al. 2010 ). Spatial empirical B ayes smoothing also referred to as a shrinkage metric, applies the global incidence estimate Areas with low variance, associated with larger populations, are adjusted li ttle, while high variance estimates associated with small samples sizes (rural zip codes) are adjusted toward the regional mean. T he resulting smoothed incidence rates are arguably better representations of true spatial patterns as compared with raw incide nce rates (Haddow and Odoi, 2009). In the absence of smoothing, it is single zip codes with a high NTM incidence surrounded by zip codes with low or no incidence, as those NTM rates may exceed estimates of the actual occurrence of disease ( Owusu Edusei and Owens, 2009 ). The spatial B ayes smoothing routine in GeoDa 0.9.5 i (GeoDa Center, Tempe AZ ) was used to adjust incidence rates from low case numbers in some zip c odes ( Bernardinelli and Montomoli, 1992; Clayton and Bernardinelli, 1997; Bithell, 2000; Odoi et al., 2003). Our results indicated similar calculated average and maximum incidences from raw and smoothed data, suggesting that this method did not significant ly change our results (Table 5 1). Spatial Analys e s To evaluate spatial autocorrelation and dependency for pulmonary and disseminated NTM hospitalizations both with and without HIV co illness for each year,

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144 the univariate (Anselin, 1995) was employed in GeoDa 0.9.1 i. A 1 st order rook weights matrix was used to define neighbors as Thiessen polygons that shared a common boundary. Significance was tested with 999 perumations and = 0.05. Outputs were defined as spatial clusters when polygons with high or low incidence are associated with neighbors of similar high or low incidence (high high and low low clusters, respectively). Conversely, spatial outliers are defined as a polyg on of high or low incidence surrounded by opposite values (Anselin, 1995). Twelve incidence maps and 12 LISA analyses were generated. Results This study determined the incidence of pulmonary and disseminated NTM disease with and without HIV co illness in Florida based on hospital discharge diagnoses. HIV co illness occurs in 20.63% and 65.56% of pulmonary and disseminated NTM disease cases, respectively T he incidence of pulmonary and disseminated NTM hospitalizations were individually estimated for all F lorida zip codes and were geospatially analyzed. Geographic location for NTM patients was mapped based on home zip code. Spatial Distribution of P ulmonary NTM I ncidence of pulmonary NTM hospitalization ranged from 0 to 130.28 per 100,000 persons ( Table 5 1 ) D istribution was wider than for disseminated NTM hospitalization with approximately 65% of all zip codes reported at least one case of pulmonary NTM for all three years combined (Table 5 1). Cases with HIV co illness were reported in 21% of zip code s and without HIV co illness in 60% of zip codes. Yearly ranges were 9 12% with HIV co illness and 34 37% without HIV co illness.

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145 Pulmonary NTM hospitalizations with HIV co illness tended to occur around urban areas such as Jacksonville, Tallahassee, Ga inesville, Orlando, Tampa, St. Petersburg, Sarasota, Naples, Fort Pierce, Boca Rato n, Fort Lauderdale, and Miami, as well as around Lake Okeechobee Cases with out HIV co illness had a more widespread distribution that included urban areas ( Jacksonville, Daytona Beach, Orlando, Tampa, St. Petersburg, Bradenton, Fort Meyers, Naples, Melbourne, Port St. Lucie, Fort Lauderdale, Miami, and Homestead), as well as major roadways ( I 4, I 10, I 75, I 95, and the Florida Turnpike ) and waterways Waterways included both the Atlantic and Gulf of Mexico coastal areas from central Florida southward, Lake Okeechobee, the Santa Fe River, the Aucilla River and in 2008 the addition of the (Figure 5 2) Spatial Distribution of D isseminated NTM Dis seminated NTM hospitalizations ranged from 0 to 121.46 per 100,000 persons ( Table 5 1 ) A pproximately 55% of all zip codes reported at least one case of disseminated NTM disease for all three years combined. Cases occurred in 32% and 41% of zip codes with and without HIV co illness, respectively Y early ranges for disseminated NTM hospitalizations ranged from 17 20 % regardless of HIV co illness status Disseminated NTM hospitalizations with HIV co illness occurred almost exclusively in metropolitan areas s uch as Jacksonville, Fort White Tallahassee, Orlando, Tampa, St. Petersburg, Sarasota, Naples, Fort Lauderdale, Miami and Homestead, rarely occurring outside of cities O ne Fort Lauderdale zip code cons istently reported the highest case counts and incide nce rates in all three years.

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146 Cases with out HIV co illness had a more widespread distribution that included primarily urban areas (Pensacola, Jacksonville, Tallahassee, Orlan do, Clearwater, St. Petersburg, Tampa, Sarasota, Fort Meyers, West Palm Beach, F ort Lauderdale, Miami and Homestead), as well as major roadways (I 4, I 75, I 95, and the Florida Turnpike) L ake Okeechobee )(Figure 5 3). Clustering of NTM Hospitalization Incidence data for hospitalizations for both pulmonary and disseminated NTM disease were analyzed for spatial clustering trends. To rule out the possibility that incidence distributions noted above were due to random chance, a LISA statistic was used to d etermine non stochasticity ( Anselin, 1995; Fosgate et al., 2002 ) Geographical trends for both pulmonary (Figure 5 4) and disseminated (Figure 5 5) NTM hospitalizations were analyzed with and without HIV co illness for 2006 2008, looking for any spatial c (Pfeiffer et C luster s were noted in all four disease states, suggesting that the distribution of hospitalizations for pulmonary and disseminated NTM w ith and without HIV, are not due to chance alone. Pulmonary NTM H ospitalizations Cluster analysis for pulmonary NTM hospitalizations with HIV co illness demonstrated a linkage to cities (Figure 5 4) Cases with HIV co illness revealed hot spots i.e., a reas with high incidence surrounded by areas of low incidence in major metropolitan areas including Jacksonville, Tallahassee, Orlando, Tampa, West Palm Beach, Fort Lauderdale, Miami and Homestead No hot outliers, i.e., areas with high incidence surrou nded by areas of low incidence, were found. C old spots i.e., areas

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147 with low incidence surrounded by other areas of low incidence were found in areas containing state or nationally protected lands including Four Creeks State Forest, Nassau Wildlife Mana gement Area, Pumpkin Hill Creek Preserve State Park, Big Talbot Island State Park, Thomas Creek Conservation Area, Jennings State Forest as well as areas of the state that are scarcely populated. Cold outliers, i.e., areas with lower incidence rates than the surroun ding areas, were found on the edges of cities such as Jacksonville, Tallahassee, Fort Lauderdale, and Miami. Pulmonary NTM hospitalizations without HIV co illness also appeared to cluster primarily around cities (Figure 5 4). Cases without HIV co illness revealed hot spots in metropolitan areas, primarily coastal cities on bays or estuaries, including Melbourne, Palm Bay, Port St. Lucie, Stuart, Clearwater, Palmetto, Bradenton, Punta Gorda, Port Charlotte, Naples, Ocala, and Orlando Suburbs, as well as at the intersection of I 75 and the Florida Turnpike and along the Aucilla River. Two hot outliers were found that demonstrated no clear correlation. Cold spots were noted in areas containing state and nationally protected lands including: Ecofi na Creek Water Management Area, Lake Talquin State Forest, Apalachicola National Forest, Lake Kissimmee State Park, Kissimmee Prairie Preserve State Park, Everglades National Park, Osceola National Forest, Ocala National Forest, Greenswamp, Greenswamp Wild life Management Area, Withlacoochee State Forest, Waccasassa Bay Preserve State Park, Crystal River Preserve State Park, Fakahatchee Strand Preserve State Park, Osceola National as well as scarcely populated areas particularly those in the pan handle. Cold outliers were

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148 found on the edges of cities such as Ocala, Orlando, Sarasota, Port Charlotte, Naples, and West Palm Beach. Dis seminated NTM H ospitalizations Spatial clustering analysis (Figure 5 5) revealed hot spots of disseminated NTM hospitalizations with HIV co illness in metropolitan areas including Jacksonville, Tallahassee, Orlando, Tampa, West Palm Beach, Boca Raton, Fort Lauderdale, Miami, and Homestead. No hot outlie rs were identified C old spots were noted in areas containing state and nationally protected lands including the Biscayne National Park, Everglades National Park, Lake Talquin State Forest, and the Apalachicola National Forest as well as portions of the s tate that are relatively unpopulated or scarcely populated Cold outliers were found on the edges of cities such as Jacksonville, Lake Butler, Tallahassee, Orlando, Fort Lauderdale, and Homestead For cases without HIV co illness, c luster data revealed h ot spots in cities and towns, including Vernon, Fernandina Beach, Jacksonville, Starke, Lake Butler, Crystal Riv er, Ocala, Orlando Sarasota, Port Charlotte, Venice, Vero Beach, Fort Pierce, Port St. Lucie, and Homestead, as well as at the intersection of points of I 75, I 4, and the Florida Turnpike Only one hot outlier was noted, corresponding to the town of High Springs. C old spots were noted in areas containing state and nationally protected lands including Ecofina Creek Water Management Area, Lake Butler Wildlife Management Area, Santa Fe Swamp Conservation Area, Seminole State Forest, Crystal River State Preserve, Escambia River Wildlife Management Area, Blackwater River State Forest, Yellow River Water Management, Three Forks Marsh Conservation Ar ea, Blue Cypress Conservation Area, Big Talbot Island State Park, Pumpkin Hill Creek Preserve State Park, and Four Creeks State Forest, as well as scarcely

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149 populated areas of the state, many in the northern half of the state. Cold outliers were found on t he edges of cities such as Lake Butler, Starke, Orlando, Melbourne, Sarasota, Port St. Lucie, and West Palm Beach. Discussion The main objective of this study was to evaluate the spatial and temporal patterns of pulmonary and disseminated NTM hospitalizati on rates, respectively, across Florida between 2006 and 2008. Our results clearly show that both pulmonary and disseminated NTM tend to cluster around urban areas. There may be a correlation with roadways and coastal living that needs to be explored furt her. The use of hospital discharge data may grossly underestimate the number of cases of NTM disease across the state of Florida. First, our data represents a hospitalized population, w hereas most pulmonary NTM diseases are diagnosed and managed in an ou tpatient setting and that information is not reported to the AHCA database Based on clinical observations, there may be approximately a 10:1 ratio of outpatient to inpatient NTM patients (M Lauzardo and K Fennelly, Southeastern National Tuberculosis Ce nter, personal communication ). Thus, incidence trends are likely to be different for outpatient settings, and may be up to tenfold higher than rates based on hospitaliz ation Additionally, the use of outpatient data might allow for inclusion of other myc obacterial diseases such as cutaneous manifestations, which are believed to be the most common NTM manifestation (Griffeth et al., 2007). Additionally, since pulmonary NTM is not considered a common condition, hospitalizations identified by use of ICD 9 c odes likely underestimate the impact of pulmonary NTM (Bilinger et al. 2009). The dataset used in the study was de identified, preventing determination of whether any patient s had multiple hospitalizations within a

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150 given year Given the relative rarity of the disease, it is unlikely that this would result in a substantial overestimation of the true impact of pulmonary NTM, however. Taking all these factors into account, it is likely that using hospital discharge billing codes to estimate incidence rates may significantly underestimate the true incidence of disease. Incidence Zip code level incidence of hospitalization for pulmonary NTM ranged from 0 130.28/ 100,000 persons, and disseminated NTM hospitalizations ranged from 0 121.46 /100,000 persons R at es are not uniform across the state, so there are likely some external factors controlling the distribution of NTM disease within the state. Hospitalization incidence rates and maps were generated from reported home zip codes of persons admitted for NTM d isease as a means to visualize where these persons reside, hence where they were most likely exposed to their NTM. Both pulmonary NTM and disseminated NTM hospitalizations demonstrated a fairly broad distribution representing 65% and 55% of zip codes re spectively, across the three years of this study (Table 5 1). Pulmonary NTM hospitalizations without HIV co illness had the broadest distribution noted, with 60% of zip codes reporting at least one case in the three year study period and up to 37% in a on e year period Hospitalizations for other NTM states had lower s tatewide distributions. This was expected given the close ties of thes e diseases to immunocompromised states such as HIV ( Covert et al., 1999; Karakousis et al., 2004 ) and the tendency of i mmunocompromised persons to settle around cities ( Butler, 1969; Wasser et al., 1993 ; Glaeser et al., 2000 ). HIV is a major co illness in both pulmonary (20%) and disseminated (65%) NTM hospitalizations (Chapter 4), so spatial distributions were visualized both with and

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151 without HIV co illness to test for inherent trends independent of HIV status Differentiation by HIV status demonstrated common as well as unique trends in both pulmonary NTM hospitalizations (Figure 5 2) and disseminated NTM hospitalizatio ns (Figure 5 3). Pulmonary NTM hospitalizations with HIV co illness occurred primarily around metropolitan areas. Relatively few hospitalizations occurred outside of urban areas and most of those followed interstate patterns or occurred around Lake Okee chobee. The proximity to urban centers is likely explained by the geographic distribution of HIV positive individuals who often reside in urban areas and is not controlled for by normalizing the population P ulmonary NTM hospitalizations without HIV co illness also occurred primarily in metropolitan areas. Unlike pulmonary NTM hospitalizations with HIV co illness, however, they also spread outside of these urban areas, primarily f ollowing interstate patterns, coastal regions from central Florida southwa rd, and the Aucilla River. Coastal living may be a risk factor for pulmonary NTM disease, as almost every coastal zip code from central Florida southward has reported hospitalizations As this pattern begins in central Florida, there is likely some envir onmental change occurring at this level. Tem perature differences between northern and southern Florida may explain this trend. Mycobacteria can grow over a wide range of temperatures (George et al., 1980), but many grow best at warmer temperatures (Griff ith et al., 2007), often preferring tropical regions of the world (Fine, 1995). The higher average temperatures and humidity in southern Florida are thought to favor mycobacterial growth and survival in aerosol droplets (Bilinger et al., 2009) thereby co ntributing to increased infection rates

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152 and subsequent hospitalizations. The panhandle and northern Florida however, experience much cooler temperatures than central and south Florida (Greller, 1980 ; Cathey et al., 1998 ) and so may not provide year roun d growth conditions as favorable as south Florida Disseminated NTM hospitalizations also occurred primarily in metropolitan areas Cases with HIV co illness were localized to major cities. This trend is, again, most likely due to the population distribut ion of HIV infected individuals, as over 65% of persons with disseminated NTM are co infected with HIV. R emoving HIV co illness appears to widen the distribu tion of disseminated NTM cases, supporting the above hypothesis T he majority of persons hospital ized with disseminated NTM without HIV co illness, however, still resided in cities, with non urban hospitalizations primarily following interstate patterns with a possible association with select waterways. Together, several common trends were noted. F irst, hospitalizations for both pulmonary and disseminated NTM, with and without HIV co illness, occurred primarily around population centers. Secondly, non urban hospitalizations both with and without HIV co illness appeared to follow interstate pattern s. Roads themselves are not thought to pose a risk of infection, but the tendency of people to settle near transportation routes (Lichter and Fuguitt, 1980) likely explains this effect, suggesting a correlation with areas of increased population. This ma y be especially true for elderly and immunocompromised persons who would likely live near routes capable of transporting them to and from care centers. Thirdly, environmental factors may play a role in the distribution of hospitalizations for NTM disease Hospitalizations may occur more regularly around bodies of water,

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153 particularly lake Okeechobee, the Aucilla River, and both coastal regions. These trends need to be further analyzed, but they are not entirely unexpected, as NTMs, including pathogenic s trains, have long been known to grow in water (George et al., 1980; von Reyn et al., 1993; Falkingham et al., 2001; Falkingham, 2011). T emperature may also contribute to the distribution of hospitalizations, as previously discussed. Cluster Analysis The trends noted, while interesting, required statistical analysis to determine if they were true patterns or the result of random distribution. LISA cluster analysis tools were used to determine if any areas held significant spatial clustering patterns and so were non random Pulmonary NTM hospitalizations cluster primarily around urban areas. P u lmonary NTM hospitalizations with HIV co illness hotspots tended to occur aroun d major cities, such as Miami. T h is was expected, g iven the trends noted on the i ncidence maps and the increased HIV population in cities ( Wasser et al., 1993 ). C old spots localize d to areas around state or nationally protected lands or to areas of the state that were scarcely populated This trend does not seem to exemplif y a lack of mycobacterial growth in these areas, but more likely reflects the fact that fewer people live and travel to these areas. An inh erent assumption of this method is that people are more likely infected close to home. Cold outliers occurred at the edge of ci ties, emphasizing the settling trends of infected persons toward cities. Taken together, the distribution of hospitalized persons with pulmonary NTM and HIV co illness appears to be largely driven by human populations, most likely based on settling patter ns of those persons infected with HIV.

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154 P ulmonary NTM hospitalizations without HIV co illness clustered in coastal cities on bays and estuaries beginning in central Florida and extending south, as well as at the intersection point of two major interstates and along select rivers. The waterways noted were the same ones noted in the incidence maps, and should be further evaluated. Highway intersection points again likely reflect settling and migratory patterns. Many of these urban hotspots occurred along bays and estuaries, which tend to have more brackish waters. NTMs grow in both fresh and brackish waters (George et al., 1980) with higher growth rates reported in waters containing 1% NaCl (brackish) than in fresh water (George et al., 1980; Pedley et al ., 2004), likely explain ing the high numbers of NTMs isolated from the tidal waters of large estuaries, like the Che sapeake Bay (Kane et al., 2007). Contrarily, NTMs do not grow in high salinity situations such as seawater (3% N aCl) (Falkingham et al., 19 80), li kely explaining the occurrence of hotspots in cities along bays. Cold spots and cold outliers showed the same trends noted above, likely for t he same reasons In summary, hospitalizations for pulmonary NTM without HIV co illness appear to positive ly correlate with major cities many along bays and estuaries and to negatively correlate with protected lands or unpopulated areas Hospitalizations for d isseminated NTM with HIV co illness appear ed again to correlate with the settlement tendencies of i nfected persons. H otspots f or disseminated NTM hospitalizations with HIV co illness tended to cluster once again around cities particularly those in south Florida. Cold spots were found to localize to areas containing state and nationally protected land s and relatively unpopulated areas of the state, and cold outliers were again found to correlate with the edges of major cities. Taken

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155 together, it appears that disseminated NTM in HIV infected persons also seems to be largely driven by the human populatio n Types of h ot and cold spots and outliers for disseminated NTM hospitalizations without HIV co illness were similar to those described for disseminated NTM with HIV co illness, except that cold spots occurred more often in the northern portion of the sta te and panhandle. Persons with an immune deficiency have the greatest likelihood of contracting disseminated disease due to NTMs (Howard and Byrd, 2000), with AIDS carrying the worst prognosis for disseminated NTM disease (Falkingham, 2003). As most immun ocompromised persons tend to live in cities ( Wasser et al., 1993 ), the linkage of disseminated NTM to cities is not surprising. It does, however, call to question some of assumptions pertaining to highly active antiretroviral therapy (HARRT). Disseminate d NTM disease used to be a major cause of death in immunocompromised patients ( Covert et al., 1999; Howard and Byrd, 2000 ; Karakousis, et al., 2004 ), but it rarel y manifests at CD4 counts greater than 100/mm 3 ( Falkingham, 2003 ) HARRT therapy is believed to have reduced the number of persons reaching low CD4 counts, and therefore decreased the number of persons experiencing disseminated NTM disease (Horsburgh, 1991; Aberg et al., 1998; Horsb urgh et al., 2001; CDC, 2002). Prior to advanced HAART therapy, M kansasii was found to spatially track with the HIV positive population (Bloch et al., 1998). I t appears however, disseminated NTM disease may still track closely with the HIV infected population d e spite advances in HARRT therapy This leads us to quest ion, despite lowering mortality, has HARRT therapy truly decreased the prevalence? I t is possible that immunocompromised persons, especially

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156 HIV infected persons, may be colonized with these organisms, rendering them more susceptible to NTM disease. Fin al Thoughts In summary, i ncidence of NTM hospitalizations at the zip code level demonstrated variability in the occurrence of cases across zip codes with some areas reporting substantially higher incidence rates, up to 124.00 /100,000 persons, than previou sly (Table 5 1) Spatial analysis of both pulmonary and disseminated NTM hospitalizations, both with and without HIV co illness, suggest that pulmonary NTM patients cluster around major cities most near the coast while disseminated NTM patients clustered around large metropolitan areas. Both NTM states likely cluster in urban areas as more immunocompromised persons live within cities ( Butler, 1969; Glaeser et al., 2000 ). For both states, reg ardless of HIV status, cold spots occurred in state and national protected areas, as well as scarcely populated areas. Taken together, living in urban areas may be a risk factor for increased hospitalizations for NTM disease. Further studies are needed t o determine if coastal living or living closer to water is a risk factor, as coastal regions and particular waterways were observed near higher incidence areas in this study.

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157 Table 5 1 Caseload, zip codes (zips) reporting, incidence for both raw and smoothed data, and maximum incidence noted in any given zip code for pulmonary and disseminated NTM yearly and aggregated data. Data was derived from discharge diagnoses, 2006 2008 NTM category Total cases Number of zips reporting Percent of zips reporting Florida statewide incidence Spatial Bayes smoothed incidence Raw max incidence SB smoothed max incidence Pulmonary NTM with HIV 06 172 86 09.1% 0.93 0.84 108.01 097.40 Pulmona ry NTM without HIV 06 645 329 34.8% 3.36 3.65 105.37 055.30 Pulmonary NTM with HIV 07 159 92 09.7% 0.83 0.77 046.57 033.70 Pulmonary NTM without HIV 07 638 330 34.9% 3.30 3.46 051.18 042.90 Pulmonary NTM with HIV 08 192 115 12.2% 1.01 0.86 075.59 023.70 Pulmonary NTM without HIV 08 729 358 37.8% 3.78 4.18 121.46 090.70 Disseminated NTM with HIV 06 543 169 17.9% 2.81 2.48 130.28 124.00 Disseminated NTM without HIV 06 246 165 17.4% 1.27 1.31 048.36 032.80 Disseminated NTM with HIV 07 499 170 18.0% 2.63 2.10 053.04 070.80 Disseminated NTM without HIV 07 249 167 17.7% 1.30 1.43 048.36 034.40 Disseminated NTM with HIV 08 483 164 17.3% 2.47 2.09 061.46 079.70 Disseminated NTM without HIV 08 306 193 20.4% 1.59 1.70 080.97 074.30

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158 Figure 5 1. Reference map of Florida showing major roadways, cities, and water systems.

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159 Figure 5 2. Incidence maps of pulmonary NTM disease 2006 2008, with and without HIV co illness.

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160 Figure 5 3. Incidence maps of disseminated NTM disease 2006 2008, with and without H IV co illness

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161 Figure 5 4. LISA maps showing cluster analyses of pulmonary NTM disease 2006 2008, with and without HIV co illness

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162 Figure 5 5. LISA maps showing cluster analyses of disseminated NTM disease 2006 2008, with and without HIV co illnes s

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163 CHAPTER 6 FINAL CONCLUSIONS Overview T he number and diversity of mycobacteria may be altered regionally by the chemistry of natural waterways and these effects may influence the relative risk for NTM in the general population. Existing methods for measur ing Mycobacterium spp. have proven inadequate so a novel qPCR assay was designed for detection and quantitation of NTM. Field samples from surface waters and municipal systems pre and post treatment demonstrated the ubiquitous presence of NTMs and MAC. W ater quality analyses yielded information on potential correlations between various parameters and the diversity of the organisms. On the basis of hospitalization records for 2006 2008 from Health Care Administration (AHCA ) p ulmonary NTM disease appears to be more common in elderly, white females whereas disseminated NTM disease is more common in middle aged, African American males. For both NTM states, most infected persons were found to live in urban areas M unicipal source s may provide a means for the distribution of these organisms to households and serve as a source of infection for high risk patients Findings from t h e current study suggest that variations in the quality of municipal waters may a ffect the growth of NTMs and in turn, the infection risk. This study contributes to the field of mycobacterial research through the development of a new screening mechanism for NTM in environmental sources that is more sensitive, specific, and rapid than traditional methods. C ul ture based techniques have been used historically (von Reyn et al., 1993; Iivanainen et al., 1993; Iivanainen et

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164 al., 1999; Bland et al., 2005) but are not without shortcomings O nly a small fraction of the total NTMs are recovered or enumerated using the se methods, and the efficiency varies among species ( Steingrube et al., 1997; Griffith et al., 2007; Heidari et al., 2010 ) Since t here is no one medium or culture condition that works best for all Mycobacterium species, results obtained by different rese archers have lacked reproducibility (Redmond and Ward, 1966; Hunter et al., 2001; Yeboah Manu et al., 2004 ; Griffith et al., 2007 ; El Bohy et al., 2009). In addition, the relatively long mycobacterial incubation time of weeks to months opens the door for other bacteria to overgrow cultures, and the process of decontamination can adversely affect t he quantity and richness of the species recovered (Iivanainen 1995; Iivanainen et al., 1997; Jacobs et al., 2009). Further, NTM colony counts are often ten fold l ower than cell counts ( Angenent et al., 2005 ). Many of the se issues can potentially be overcome through the use of DNA detection methods without the need for culture (Nadkarini et al., 2002 ; Ghosh et al., 2006). The general approach involves isolating al l DNA present in a sample and measuring specific mycobacterial sequences from the subsequent pool of DNA ( Schochetman et al., 1988; Nadkarini et al., 2002). Since the concentration of mycobacterial DNA from environmental sources is often low, PCR can be u sed to amplify target sequences to detectable levels (Wang et al., 1996; Stinear et al., 2000; Marsollier et al., 2002; Pedley et al., 2004). In recent years qPCR technologies have gained favor as a way to rapidly enumerat e organisms or genes from enviro nmental samples (Takai and Horikoshi, 2000; Smythe et al., 2002; Brinkman et al., 2003; He and Jiang, 2005). Through the use

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165 of fluorescent reporter molecules the technique allows for continuous reaction monitoring and evaluat ion at the peak of the expone ntial phase This reduc es variations based on reagent depletion or assay efficiency related to end point reads While PCR based methods show potential, they remain limited by the efficiency and reproducibility of cell lysi s and the selectivity, sensitivi ty and availability of primers ( Steingrube et al. 1997; Heidari et al., 2010; Kay et al., 2011 ). Effective PCR requires species specific sequence based primers ( Schochetman et al., 1988 ) D e spite a strong need in the clinical laboratory, de finitive mar kers to differentiate each of the subspecies within the highly homogeneous Mycobacterium tuberculosis complex were not developed until 2002 (Brosch et al., 2002). It is not surprising that progress has been even slower for the less well characterized NTMs In many ways this was due to a lack of sequence information from which to design sensitive and specific primers ( Kirschner et al., 1993 ). In recent years, more whole genome sequences of NTMs have been completed (Garnier et al., 2003; Stinear et al., 20 08; Castellanos et al., 2009; Kaser et al., 2009; Kaser et al., 2009; Wynne et al., 2010). Genomic comparison of different mycobacterial species en able d identif ication of a region of the 1 6S rRNA gene that appears to be genus specific. This discovery is i mportant as previously published primer and probe sets for the genus mycobacteria often also amplify closely related Actinomycetales (Taylor et al., 1997; Gaafar et al., 2001; Sheng et al., 2009). The MAC complex subgroup was chosen as a target for prime r development due to the significant levels of associated morbidity and mortality,

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166 as well as the existence of several published complete genomes for each of the species within this complex ( Paustian et al., 2008; Castellanos et al., 2009; Wynne et al., 20 10 ). These methods show promise for environmental measurements, although samples can be difficult to work with because of high levels of background organic material that often co purifies with DNA ( Tebbe et al., 1993; Wilson, 1997 ). E nvironmental compoun ds such as humic and fulvic acids are capable of inhibiting Taq polymerase and thereby inhibiting the PCR reaction ( Tebbe et al., 1993; Wilson 1997 ). S everal companies have designed kits to remove such contaminants at the time of DNA extraction or prior to PCR (Rochelle, MO BIO, etc). Despite these limitations, direct DNA methods provide an absolute indication of the presence or absence of mycobacteria and can be quantitative (qPCR) (MacGregor et al., 1999; Stinear et al., 2000). T he new primers were use d to test water samples collected in south Florida. Eubacterial universal primers detected more bacteria than genus specific primers, which, in turn, detected more than MAC primers as expected These results were confirmed by culture and by sequencing o f the PCR ampli cons The study demonstrated the ubiquitous nature of these organisms in the environment and their presence in municipally distributed water. M ycobacteria and MAC were present in all samples, and mycobacterial numbers appear to increas e post treatment. These findings suggest that mycobacteria live within the source waters, at least a portion survive water treatment procedures, and the surviving NTMs go on to repopulate the distribution system along its length most likely in the form of biof ilms

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167 This study contributes to a growing body of evidence that people may be acquiring NTM infections from organisms present in water, possibly municipal waters. Exposure to NTMs without the development of overt symptoms, but with the occurrence of an i mmunological response, is relatively common (Edwards and Smith, 1965; Smith, 1967). Combining this with the apparent ubiquitous nature of NTMs, it appears the majority of people must be relatively resistant to most environmental NTMs. For this reason, fu rther reductions in environmental exposure are unlikely to significantly decrease risk. Still, for vulnerable populations such as children, the elderly, pregnant women, and immunocompromised persons, there is value in reducing potential sources of exposur e from municipally distributed waters through devices such as whirlpools, indoor pools, and showers (Feazel et al., 2009; Ingen et al., 2010; Falkingham, 2010 ). This study was the first attempt to identify variables in both environmental and municipal sou rces that contribute to mycobacterial growth using a quantifiable, molecular method. Phosphorous likely has an effect on mycobacterial growth in municipal samples, but this effect is likely the product of the stimulatory effect of phosphorous on microbial growth in an environment with decreased levels of competitors. Further work is needed to clarify parameters affecting mycobacterial distribution. Why do some persons become infected with NTMs while others evade disease? Unfortunately, there have been fe w published studies that describe the populations infected by these organisms (Winthrop, 2010). To determine whether there is a link between water sources and infections, the demographic characteristics of persons infected with pulmonary or disseminated N TM disease were examined. It had been

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168 estimated that 1.8 out of 100,000 individuals are infected by non AIDS related recise incidence and prevalence data is not available. L aborator y surveys across the United States and Europe have been limited by the fact that they are based on culture s rather than on patients (Abe et al., 1992; Woods et al., 1996). Also unlike tuberculosis NTM disease is not reportable in the U .S. (Arend et al., 2009; Winthrop et al., 2009) so the incidence likely remains largely under estimated ( Gopinath, 2010; Benwill et al., 2010 ). A statewide reporting system of hospital discharge diagnoses was established in 1993, but NTM disease as a whole remains non repo rted. A 1987 survey of state and city public health departments revealed that over 90% of all NTM isolates from these locations were respiratory in origin, but likely gave a substantial underestimate of incidence and prevalence. TB controllers have estimat ed incomplete sampling from across the U.S., excluded private laboratories, and took place at a time when there was under recognition of the nodular bronchiectatic form of disease. More recent laboratory based surveys across Europe, North America, Asia, Africa, and Australia suggest a rising proportion of potentially pathogenic mycobacteria (Marras and Daley, 2002). Across Europe and in regions such as Massachusetts and British Columbia, incidence rates were found to be increasing exponentially. Pooled data approximated the incidence rate to be between 1.7 4.5/100,000 persons, but regional values or variability were not reported (Marras and Daley, 2002). Incidence rates for NTM isolations in Ontario, Canada rose significantly from 9.1/100,000 in 1997 to 14.1/100,000 in 2007 (Marras et al., 2007). Increases of this nature are concerning,

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169 and the possibility that more people are becoming infected cannot be ruled out (Khan et al., 2007). Still, the increases could be a reflection of heightened awareness leading to more requests for sputum cultures and computed tomography lung scans, thereby allowing for increased recognition of the classic patterns, and subsequently more po sitive cultures (Winthrop, 2010). Alternatively, improved laboratory culture techniques, such as the use of liquid media, may have resulted in higher recovery rates than with traditional media such as Lowenstein Jenson agar ( Reddacliff et al., 2003; Redda cliff et al., 2010 ). The true reason is likely multifactorial in nature (Winthrop, 2010). Multiple factors contribute to making the southeastern U.S. an ideal site for NTM growth (Kirschner et al., 1992; Kirschner et al., 1999; Primm et al., 2004; Vaere wijck et al., 2005). One national study of hospitalization discharge codes found Florida to have the highest incidence rates of pulmonary NTM infection (2.1 2.4/100,000), and this rate increased over the study period 1998 2005 (Bilinger et al., 2009). I n the current study, hospital discharge data for more recent years, 2006 2008, put the incidence rate for pulmonary disease in Florida at 4.41/100,000, representing continued increase and supporting suggestions that in the U.S., rates of MAC, the primary p ulmonary NTM isolate, tended to be highest in states bordering the Atlantic Ocean and the Gulf of Mexico (>4.8/100,000) (Good and Snider, 1982; Griffith et al., 2007; Huang et al., 2009 ). Florida abuts both of these waterways, so it is easy to see why the state would be expected to have similarly high rates. The difference compared with rates reported by are likely attributable to survey method. Those studies used laboratory isolates, which may represent colonization

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170 rath er than infection, as a measure of disease burden, whereas Bilinger et al. and the present study used hospital discharge codes. Until NTMs become reportable, it remains unclear which of these approximation methods, if any, is best. The use of hospital d ischarge codes is likely to seriously underestimate the true incidence of NTM disease because outpatient cases are not included. This problem is compounded by the difficulties in diagnosis. Pulm onary NTMs appear to be more common in elderly females. Usin g the microbiologic component of the American Thoracic Society/Infectious Diseases Society of America's pulmonary NTM disease criteria to define cases of pulmonary NTM one study estimated the statewide prevalence rate within Oregon to be 5.6/100,000 perso ns, and found a correlation with pulmonary NTM and age (Cassidy et al., 2009). The prevalence was 15.5/100,000 for those over 50 years of age, and greater than 20/100,000 in those over 70 years of age. Almost 60% of these patients were female (6.4/100,0 00 for women and 4.7/ 100,000 for men). Similarly, Bilinger et al. reported the highest annual prevalence rates in women aged 70 years and older (9.4/100,000) compared with similarly aged men (7.6/100,000) (Bil inger et al., 2009). Both these studies portr ay this disease as disproportionally affecting elderly females, and demonstrate the clinical significance of this disease with incidence rates surpassing those of TB (5.2/100,000) ( Wolinsky 1979; CDC, 2009; Winthrop 2010). Likewise, the current study fo und a predominance of elderly (61.18% aged 60+) females (52.19%), with the highest reported incidence in women over 70 (22.11/100,000). Together, these studies demonstrate that pulmonary NTM is not an uncommon disease amongst the elderly and document what many experts and clinicians have suggested for over a

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171 decade: this is no longer a male dominated disease. These findings suggest that incidence will continue to rise given projections that as many as 1 in 5 individuals will be classified as elderly by 202 0 (Day, 1996), and that women have longer life expectancies and tend to make up the majority of the elderly population (CIA, 2010). Further, the current trend in the United States and other countries for the elderly to retire to warm, moist environments s uch as Florida, may place these persons at further risk for NTM disease (Rappaport, 2007). Additional risks are associated with particular diseases, such as immunocompromised states, CF, or COPD, most of which are more common in the elderly (Barnes and Ce lli, 2009). The profile for disseminated NTM disease largely matches trends within the HIV infected population. Currently, two and a half million people in industrial countries (United States, Canada, Australia, New Zealand, Japan, and Western and Easte rn Europe) are estimated to be living with HIV, most of whom have or will have access to antiretroviral therapy (Wood et al., 2003; CDC, 2008; Stall et al., 2009). Within the United States, the majority of these infected persons tend to be African America n males in their 30s and 40s (CDC, 2008; CDC 2010 ). Given the strong historical ties between disseminated NTM and HIV (Nunn and McAdam, 1988), it is unsurprising that our population based data indicated that the majority of persons hospitalized for disse minated NTM disease tended to match this profile. Given the widespread use of drop sufficiently to allow for disseminated NTM disease (Shepherd et al., 2010). Despi te this, hospitalization rates for disseminated NTM (4.03/100,000) still appear to be relatively high, approaching state TB levels ( 5.2/100,000 ) ( CDC, 2009) It is therefore

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172 possible that the view of disseminated NTM disease in developed nations, especiall y in the HIV infected has been oversimplified, and carrier or unrecognized infections could be occurring in this population. The current study contributes to a growing body of evidence linking pulmonary disease to elderly, white females, and disseminated disease to HIV profiles, and goes on to further describe these persons with regard to insurance status, length of stay, and commonly associated co illnesses. Patients paid primarily with government insurance, providing possible linkages to lower socio econ omic status. Additionally, patients stayed in the hospital on average over 11 days over two times the national average for any reason or for an infectious disease (DeFrances et al., 2003), thereby demonstrating the true severity of illness in these patien ts. Associated co illnesses varied with NTM disease, but were largely associated with immunocompromised states such as pancytopenia and HIV. T here are virtually no population based studies documenting basic epidemiological f NTM disease (Winthrop, 2010). Mapping of zip codes for persons discharged from the hospital with a diagnosis of NTM disease revealed that while pulmonary NTM may have a wider overall distribution than disseminated NTM both disease states seem to occur primarily in or around urban areas. T he tendency for elderly and immunocompromised people to settle in these areas may explain why cases focus in these areas, but does not account for why people become infected there ( Butler, 1969; Wasser et al., 1993; Gla eser et al., 2000 ). The distribution of NTM disease in urban areas may be driven by exposure to municipal waters. Cassidy et al. previously determined that in Oregon, significantly

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173 higher NTM rates were detected in the western, more urban portion of the s tate (Cassidy et al., 2009). U rban areas are more likely to use large, municipal water systems than are rural areas whose primary water source may be wells. Water in municipal systems can be stored for long periods in both pipes and reservoirs, thereby p roviding opportunities for NTM growth (Cassidy et al., 2009). Further, given the home and the treatment facility, as well as the general lack of competition within these si tes, it is conceivable that NTMs may grow to high levels in biofilms within distribution lines (Falkingham et al., 2001). Indeed, the growth of NTMs within distribution systems was previously hypothesized in the 1970s and 1980s as an expla nation for the h igher incidence of MAC found in urban communities (DuMoulin et al., 1985). Diagnostic bias and climate may also explain, in part, this trend toward NTM disease in urban areas, as persons residing in urban areas may be more likely to seek medical care tha n persons residing in rural areas ( Sudha et al., 2003 ) and facilities in urban areas may have more experience in diagnosing these infections Further, patients with predisposing conditions such as COPD or HIV more commonly reside in urban areas with bett er access to medical treatment facilities ( Butler, 1969; Wasser et al., 1993; Glaeser et al., 2000 ). In terms of climate, wetter and more temperate, conditions in the more urban western Oregon promote NTM growth over that in the more arid, dry e astern part of the state ( Kirschner et al., 1999; Falkingham, 2009 ; Cassidy et al., 2009). On the other hand, and yet increased rates are noted in urban areas ( Moon and Han, 2011 ). Despite this, climatic factors may he lp explain continued presence of NTMs in certain surface waters

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174 that are subsequently used as municipal source waters. Environmental sampling has indicated that NTM organisms are present in the environments of most regions (von Reyn et al., 1993) so geog raphic variation in the prevalence of MAC infection and disease is more likely the result of differences in the opportunities for exposure to environmental sources rather than the result of presence or absence of MAC in the environment. Pulmonary NTM infe ctions appear to have increased incidence along the coastline in southern Florida but not in the northern part of the state. The milder climate in the south provides more opportunity for growth in source waters, as the ground is not frozen during the wint er months and the agricultural season is longer (von Reyn et al., 2001). These surface waters may then be used as municipal sources, thereby allowing a fairly constant flow of organisms into municipal supplies. T his may help explain the increased rates of infection of NTMs long noted in the s outheastern United States ( Edwards and Smith, 1965; Smith, 1967 ). There is also a cluster of cases with potential linkage to the Aucilla River in the panhandle. Confirmation of the significance of these environmental linkages will require further analysis and are hampered by the low numbers of cases of NTM infection in this study and a lack of information on water usage habits. This is further complicated by the likelihood that each species of NTM needs to be analyze d separately and that only diagnoses from hospitalized patients were available. Final Thoughts This study contributes to a growing body of evidence linking NTMs to water. Having developed a fast, quantitative way to detect all mycobacteria and the MAC subgroup, the study went on to demonstrate the growth of these mycobacteria in municipal and surface waters, the demographic profile of those hospitalized with NTM

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175 disease, and the distribution of hospitalizations around the state. The majority of mycobact erial hospitalizations tend to occur in urban areas and along the coast of south Florida. This linkage to urban areas is likely driven in large part by the growth of NTMs in municipal waters, although further studies will be needed to confirm this. Additi onal epidemiologic work is needed to determine disease risk factors and identify potentially modifiable exposures for high risk populations. If it is true that most patients are infected from public water supplies, efforts should be made to better underst and the factors contributing to NTM concentrations in municipal water supplies, the risk of these potential pathogens, and ways to reduce those risks (Winthrop, 2010)

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236 BIOGRAPHICAL SKETCH Stephanie C. Yarnell is the daughter of Howard and Donna Yarnell of Mansfield, Texas. She grew up in Atlanta, Georgia, and graduated valedictorian of Pickens County High School in 2002. Stephanie went on to attend the University of Georgia w here she graduated Summa c um Laude with highest honors in 2006 w ith a B.S. in b iology, B.S. in m icrobiology, and a B.S. in e cology. While in her undergraduate studies she completed a honors thesis entitled, ar Award, as well as a Biomedical Research Fellowship. In 2006, she entered the Medical College of Georgia pursuing a combined M.D./Ph.D degree program. Upon completing the first two years of medical school, she transferred to the University of Florida i n 2008 to begin her Doctor of Philosophy studies in th e Interdisciplinary Program in b iomedical s ciences within the College of Medicine concentrating in immunology and microbiology While at the University of Florida, she has served as a member of the adm issions committee for the M.D./Ph.D Program in the Colleg e of Medicine and as a Physical Exam Teaching Associate for the College of Medicine. In 2011, she was awarded the prestigious P.E.O Scholar award. She received her Ph.D. from the University of Flor ida in summer 2011. Upon completion of her Doctor of Philosophy studies she re matriculate d into her third year of medical school at the University of Florida College of Medicine, and is expected to graduate from medical school in 2013.