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Applied and Environmental Microbiology, September 2006, p. 5864-5869, Vol. 72, No. 9
0099-2240/06/$08.00+0 doi:10.1128/AEM.00759-06
U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Research Triangle Park, North Carolina 27711,1 U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Cincinnati, Ohio 45268,2 Centers for Disease Control and Prevention, National Center for HIV, STD, and TB Prevention, Division of TB Elimination, Atlanta, Georgia 30333,3 U.S. Environmental Protection Agency, Region 10 Laboratory, Port Orchard, Washington 98366,4 Clark County Water Reclamation District, Las Vegas, Nevada,5 U.S. Environmental Protection Agency, Office of Research and Development, National Homeland Security Research Center, Cincinnati, Ohio 452686
Received 31 March 2006/ Accepted 24 June 2006
There is evidence that drinking water may be a source of infections with pathogenic nontuberculous mycobacteria (NTM) in humans. One method by which NTM are believed to enter drinking water distribution systems is by their intracellular colonization of protozoa. Our goal was to determine whether we could detect a reduction in the prevalence of NTM recovered from an unfiltered surface drinking water system after the addition of ozonation and filtration treatment and to characterize NTM isolates by using molecular methods. We sampled water from two initially unfiltered surface drinking water treatment plants over a 29-month period. One plant received the addition of filtration and ozonation after 6 months of sampling. Sample sites included those at treatment plant effluents, distributed water, and cold water taps (point-of-use [POU] sites) in public or commercial buildings located within each distribution system. NTM were recovered from 27% of the sites. POU sites yielded the majority of NTM, with >50% recovery despite the addition of ozonation and filtration. Closely related electrophoretic groups of Mycobacterium avium were found to persist at POU sites for up to 26 months. Water collected from POU cold water outlets was persistently colonized with NTM despite the addition of ozonation and filtration to a drinking water system. This suggests that cold water POU outlets need to be considered as a potential source of chronic human exposure to NTM.
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