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OCCURRENCE OF HETEROTROPHIC BACTERIA WITH VIRULENCE CHARACTERISTICS IN POTABLE WATER
Citation:
Smith, B G., D J. Lye, AND J W. Messer. OCCURRENCE OF HETEROTROPHIC BACTERIA WITH VIRULENCE CHARACTERISTICS IN POTABLE WATER. Presented at American Society for Microbiology 101st General Meeting, Orlando, FL, May 20-24, 2001.
Impact/Purpose:
Develop data for use in assessing the efficacy of the in vitro virulence tests in predicting pathogenicity of heterotrophic bacteria and in assessing risk of infection by opportunistic pathogens in potable water and to attempt to identify possible opportunistic pathogens among the heterotrophic bacteria that occur in drinking water, while determining the influence of type of source water or treatment technology on the occurrence of opportunistic pathogens.
Description:
Treated potable water contains a variety of heterotrophic bacteria that survive current treatment processes. There is evidence that these bacteria are not hazardous to the healthy population, however, the possibility exists that some of them may be opportunistic pathogens capable of infecting individuals with impaired immune systems. Our laboratory is interested in possible health risk from naturally occurring levels of heterotrophic bacteria levels when they increase to high levels in water environments. Increases in heterotrophic bacteria sometimes occur at specific point-of-use elements within a distribution system, such as a water line used for hemodialysis. A battery of in vitro tests for putative virulence factors was used to screen 45 isolates from potable water cultured on TSA with sheep blood. Virulence tested included extracelluar enzyme production, cytotoxicity for Hep-2 cells and animal studies using outbred Swiss mice immunocompromised with carrageenan (200 mg/kg) to induce susceptibility to facultative intracellular pathogens. Plate-based assays for extracellular activities such as hemolysis, elastase and collagenase were not good indicators of potential virulence in the animal studies for the isolates tested. Only the present/absence of cytotoxicity correlated well with animal study results.