Pathogenic qualities of the cytotolytic entertoxin gene and hybridization group one genes of Aeromonas hydrophila in normal distribution water sources

EPA has placed Aeromonas hydrophila on the Candidate Contaminant List (6). This bacterial agent, routinely associated with cold-blooded animals is now considered a human opportunistic pathogen. Its occurrence in drinking waters is the main concern of those responsible for the water safety of the citizenry of the US and other countries. It is the goal of this study to determine the occurrence of A. hydrophila in the source, plant and distribution water of a public water supply in Indiana. Using PCR technology, it has been demonstrated in a previous study that the cytotolytic enterotoxin gene (AHCYTOEN), determined by a 232 bp marker, can be detected in all three sites in the water system, although viability studies indicate otherwise. Samples of disinfected bulk water, however, were free of the gene while biofilm samples of a simulated water system proved a possible reservoir for the organism in a viable, but unculturable form. On one occasion, viable A. hydrophila was isolated from a meter biofilm from the distribution system. PCR methods have identified toxin genes in the biofilm but not in the properly disinfected bulk water; therefore the possibility of contamination with A. hydrophila cannot be eliminated.Department of BiologyThesis (M.A.