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The persistence of Mycobacterium avium in a drinking water system, what is the risk to human health?
Citation:
Hilborn, E. The persistence of Mycobacterium avium in a drinking water system, what is the risk to human health? Water Microbiology, Chapel Hill, NC, May 18 - 21, 2015.
Impact/Purpose:
Mycobacterium avium is a biofilm-associated pathogen that is included on the drinking water contaminant candidate lists. We have demonstrated that clonal colonies of M avium can persist in drinking water distribution systems for up to 29 months despite the addition of filtration treatment. The majority of M avium were isolated from point of use sample sites, suggesting that people may experience chronic exposure to these organisms. We will discuss the implications for human health.
Description:
Drinking water is believed to be a major source of human exposure to nontuberculous mycobacteria (NTM) such as Mycobacterium avium. We monitored the prevalence of M. avium in a drinking water system during the addition of filtration treatment. Our goal was to determine if the prevalence of NTM such as M. avium would decrease after the addition of filtration. We selected a municipal system served by two water treatment plants. Water processed by the two treatment plants was sampled over a 29-month period, one plant received the addition of filtration after six months of sampling. Sites sampled included plant influent and effluent, distributed water, and cold water taps at point-of-use (POU) located in public or commercial buildings located within the two distribution systems. Water samples collected at POU sites yielded the majority of NTM with a prevalence of greater than 50% despite the addition of filtration. Overall prevalence for all sites was 25% with no reduction in the frequency of isolation of NTM after addition of filtration. Specific clones of M. avium as determined by pulsed field gel electrophoresis were found to persist at POU for up to 27 months. Our results suggest that water derived from POU cold water taps were persistently colonized despite the addition of filtration to a drinking water system. The ability of NTM to survive in biofilms in water distribution systems needs to be considered as a contributing factor to human disease. This is a proposed presentation and does not necessarily reflect EPA policy.