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Health significance and occurrence of injured bacteria in drinking waterEnteropathogenic and indicator bacteria become injured in drinking water with exposure to sublethal levels of various biological, chemical and physical factors. One manifestation of this injury is the inability to grow and form colonies on selective media containing surfactants. The resulting underestimation of indicator bacteria can lead to a false estimation of water potability. m-T7 medium was developed specifically for the recovery of injured coliforms (both "total" and fecal) in drinking water. The m-T7 method was used to survey operating drinking water treatment and distribution systems for the presence of injured coliforms that were undetected with currently used media. The mean recovery with m-Endo LES medium was less than 1/100 ml while it ranged between 6 and 68/100ml with m-T7 agar. The majority of samples giving positive results with m-T7 medium yielded no detectable coliforms with m-Endo LES agar. Over 95% of the coliform bacteria in these samples were injured. Laboratory experiments were also done to ascribe the virulence of injured waterborne pathogens. Enteropathogens including Salmonella typhimurium, Yersinia enterocolitica and Shigella spp. required up to 20 times the chlorine levels to produce the same injury in enterotoxigenic Escherichia coli (ETEC) and nonpathogenic coliforms. Similar results were seen with Y. enterocolitica exposed to copper. The recovery of ETEC was followed by delayed enterotoxin production, both in vitro and in the gut of experimental animals. This indicates that injured waterborne enteropathogenic bacteria can be virulent.
Document ID
20040089616
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
McFeters, G. A.
(Montana State University Bozeman 59717, United States)
LeChevallier, M. W.
Singh, A.
Kippin, J. S.
Date Acquired
August 21, 2013
Publication Date
January 1, 1986
Publication Information
Publication: Water science and technology : a journal of the International Association on Water Pollution Research
Volume: 18
Issue: 10
ISSN: 0273-1223
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: AI19089
CONTRACT_GRANT: AM33510
CONTRACT_GRANT: R8-07092
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Number 13-40
NASA Discipline Environmental Health
Non-NASA Center

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