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COMPARISON OF MYCOBACTERIUM AVIUM ISOLATES FROM DRINKING WATER AND FROM THE POPULATION SERVED BY THE SYSTEM
HILBORN, E. D., T. C. COVERT, M. A. YAKRUS, S. HARRIS, S. F. DONNELY, E. W. RICE, M. T. SCHMITT, S. TONEY, S. BAILEY, AND G. N. STELMA. COMPARISON OF MYCOBACTERIUM AVIUM ISOLATES FROM DRINKING WATER AND FROM THE POPULATION SERVED BY THE SYSTEM. Presented at International Conference on Emerging Infectious Diseases, Atlanta, GA, March 19 - 22, 2005.
1. To assess the prevalence of nontuberculous Mycobacterium species (NTM) in raw water, finished water, and in drinking water distribution systems before and after the addition of filtration and ozonation.
2. To assess the effect of the addition of filtration and ozonation on the percent of NTM from environmental sources that are genetically related to human isolates derived from the population served by municipal drinking water.
3. To assess the effect of the addition of filtration and ozonation on the prevalence of indicator bacteria and heterotrophic plate count bacteria in finished water and in drinking water distribution system biofilm. A comparison of strains of heterotrophic bacteria before and after the treatment change will be conducted.
4. To assess the effect of the addition of filtration and ozonation on the prevalence of other pathogens in finished water, and in drinking water distribution systems.
Background: Current evidence suggests that drinking water, soil, and produce are potential sources of Mycobacterium avium infections, a pathogen not known to be transmitted person-to-person.
Methods: We sampled water during 2000 - 2002 from a large municipal drinking water system in which surface source water is used. We cultured and isolated environmental M. avium from water samples. In addition, we collected clinical isolates identified as M. avium complex that were derived from patients served by the drinking water system and isolated during 1999 - 2002. We recorded the anatomical site from which the isolate was collected and the patient's residential zip code. Environmental and patient isolates were compared for genetic similarity using multilocus enzyme electrophoresis (MEE) as a screening tool. Isolates with similar MEE patterns were then compared more specifically by using pulsed-field gel electrophoresis (PFGE) analysis.
Results: M. avium was isolated from 73% (30/41) of water samples collected at all four point-of-use tap (POU) sample sites located in public and commercial buildings. Eight percent (9/113) of patient isolates were identified as being related by electrophoretic group to environmental isolates. Two of these related isolates displayed geographic proximity between POU sample site and patient zip code.
Conclusions: Given the large amount of genetic heterogeneity known to occur among M. avium strains, our results suggest that these 9 patient isolates were associated with exposure to municipal water. Molecular techniques are useful to identify specific environmental sources of human M. avium infections.