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VIRULENCE FACTORS OF AEROMONAS: A GENETIC CHARACTERIZATION OF DRINKING WATER ISOLATES
Citation:
Sen, K. AND M R. Rodgers. VIRULENCE FACTORS OF AEROMONAS: A GENETIC CHARACTERIZATION OF DRINKING WATER ISOLATES. Presented at Water Quality Techology Conference, Philadelphia, PA, November 1-5, 2004.
Impact/Purpose:
Investigate the occurrence of Aeromonas bacteria in potable water derived from both surface and ground water sources. Develop improved method(s) for the detection of culturable H. pylori in environmental samples and investigate the occurrence of H. pylori in potable waters.
Description:
A survey of finished drinking water conducted by the US EPA during 2000-2001, revealed that 8 out of 18 water utilities encompassing several states (NY, KY, IA, OH) were contaminated with aeromonas species. Altogether 205 organisms were isolated by EPA method 1601. All of the species were Ampicillin and dextrin resistant and the major species isolated were A. bestiarum/ A salmonicida and A hydrophila (Birkenhauer et al, 2003). A. veronii , A. caviae, A. media and A. allosacharophila were the other species that were isolated in small numbers . As an initial attempt to determine the virulence of the different species present, a PCR based genetic characterization was done for the virulent factors elastase, lipase, flagella A and B genes, the cytolytic enterotoxin act ( achytoen) and the cytolytic enterotoxins, Alt and Ast. Disruption of any of these genes causes a loss or diminishes the virulence of the species. The achytoen gene primers were earlier described by Kingcombe et al ( ). For the other genes all the available sequences available in the genebank databases were aligned and primers were designed to conserved regions among respective similar genes, from different species. PCR was done by three duplex assays using the primers to elastase and lipase together, fla and alt together, and the act, ast genes together. Lipase was present in 86% of the strains; Act in 69% of the strains; Alt and Ast in 45% and 30% of the strains respectively, fla in 55% and Elastase in 40 % of the strains. Only one strain had all the virulent genes. From a given utility more than one kind of species were found. Also within the same contaminated sample of water from a given utility, different combination of virulent factors were present in different strains of the same species. These results indicated that the entire flora need to be tested from a water sample, for the different virulent factors, as within the same species the occurrence of certain virulence factors may vary . The results also suggest that the strains isolated have the potential to be pathogenic, although, additional virulence factors, that have not been characterized, may be needed to cause disease.