Influence of Flow Rate on the Isolation of Antibiotic Resistant Enterococci.

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Enterococci are commensal bacteria that may cause infection and are naturally resistant to a number of antibiotics. Acquired antibiotic resistance is becoming increasingly common due to excessive human usage. The “superbug” vancomycin resistant enterococci (VRE) can exhibit resistance to over 10 clinically useful antibiotics. Isolation of VRE from food animals and other environmental sources has highlighted a potential environmental reservoir of antibiotic resistant enterococci (ARE). Furthermore, the environment may also contribute to the dissemination of ARE. As part of an ongoing project looking at the sources, transfers and fate of ARE in a defined catchment dominated by agricultural activities, 275 strains have been isolated from three stream water sites at low-flows over a period of six months and 180 strains have been isolated from different stages of a storm event, during which an influx of enterococci was observed. These strains were screened for resistance to a panel of antibiotics and identified to the species level. Antibiotic resistance was common in all samples and VRE was isolated on a number of occasions. Differences were observed between low-flow strains and storm-event strains with regards to antibiotic resistance, with low-flow samples giving a larger proportion of antibiotic resistant strains. At low-flows, no strains were fully susceptible, 62% were resistant to 4 or more antibiotics and 2% were resistant to 10 or more antibiotics. In contrast, from the storm event, 14% of strains were fully susceptible, 32% resistant to four or more antibiotic and no strains were resistant to 10 or more antibiotics. It is apparent that antibiotic resistance, including multiple resistance, is common at the three sampling sites at low-flows. Although an influx of enterococci is observed during storm events, these strains appear to be less resistant than those isolated from low-flows. Therefore storm events appear to have a significant influence on the overall population of antibiotic resistant enterococci.
Original languageEnglish
Publication statusPublished (in print/issue) - 19 Feb 2009
EventENVIRON 09: Irish Environmental Researchers Colloquium - Waterford Institute of Technology, Waterford, Ireland
Duration: 18 Feb 200920 Feb 2009
Conference number: 19


ConferenceENVIRON 09


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