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SENSITIVITY OF DIFFERENT AEROMONAS SPECIES TO COPPER AND SILVER
Citation:
Rodgers, M R. AND A W. Smallwood. SENSITIVITY OF DIFFERENT AEROMONAS SPECIES TO COPPER AND SILVER. Presented at American Society for Microbiology, Washington, DC, May 18-22, 2003.
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:
Aeromonas bacteria are common flora in surface and ground waters and are considered to be human pathogens. They can also be found in municipally treated drinking water, likely as a component of biofilms, as found in distribution system pipes and point of use water filters. It has been previously reported that Aeromonas bacteria are very sensitive to certain heavy metals, such as copper, found in treated drinking water and that this sensitivity affects the recovery of these bacteria from water samples. In addition, copper and silver ions are frequently employed as bactericidal agents in water filters to limit biofilm formation. Earlier studies on metal sensitivity of aeromonads did not investigate differences among species. We have undertaken the present study to investigate possible differences among Aeromonas species with regard to heavy metal sensitivities. Eleven Aeromonas species, including A. hydrophila, A. caviae, A. veronii biovar veronii and A. bestiarum (species most commonly encountered in both clinical and environmental samples) were used in the sensitivity studies. Heavy metal sensitivities of E. coli and Vibrio cholerae were also measured for comparison. Bacteria were exposed to varying concentrations of copper and silver ions in saline. Our copper sensitivity results support previous studies, indicating that Aeromonas bacteria, regardless of species, are more sensitive than E. coli to copper. V. cholerae displayed a similar copper sensitivity. Differences among Aeromonas species were seen however at exposure to 20 micromolar copper, providing a possible explanation for why certain species may be isolated more frequently than others from water. Silver, at concentration as low as 5 micromolar, had a pronounced effect on all strains tested, with the Aeromonas strains more sensitive than either E. coli or V. cholerae.