Citation:

HILBORN, E. D., T. C. COVERT, M. YAKRUS, S. F. DONNELY, E. W. RICE, S. TONEY, S. BAILEY, AND G. N. STELMA. THE PERSISTENCE OF MYCOBACTERIUM AVIUM IN A DRINKING WATER SYSTEM AFTER THE ADDITION OF FILTRATION. Presented at International Meeting on Microbial Epidemiological Markers, Victoria, BC, CANADA, May 11 - 14, 2005.

Impact/Purpose:

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.

Description:

Drinking water is increasingly recognized as a major source of pathogenic nontuberculous mycobacteria (NTM) associated with human infection. Our goal was to determine if the prevalence of NTM would decrease after the addition of filtration treatment to an unfiltered surface water source. We sampled water from two initially unfiltered surface drinking water treatment plants over a 29-month period. One plant received the addition of filtration after six months of sampling. At each plant, we sampled treatment plant influent and effluent, distributed water, and cold water taps (point-of-use (POU) sites) in public or commercial buildings located within the distribution systems. Water samples collected at POU sites yielded the majority of NTM with a prevalence of greater than 50%; overall prevalence was 25%, with no reduction in the frequency of isolation of NTM from water samples despite the addition of filtration. Specific clones of Mycobacterium avium, as determined by pulsed field gel electrophoresis, were found to persist at POU sites for up to 27 months. Our data indicate that water derived from POU cold water taps was persistently colonized despite the addition of filtration to the drinking water plant. Evidence of this ability of clonal strains of M. avium to persist within drinking water distribution systems is useful, and may be applied during the investigation of environmental sources of human M. avium infection using molecular methods.

Record Details: