Ecology of antimicrobial resistance and virulence in Escherichia coli in a rural watershed

Abstract number: P2107

Neils L., Campillo C., González G., Carter E., Angle C., Keen A., Ernst S., Singer R.

Objective: To examine the phenotypic and genotypic diversity among Escherichia coli in a rural watershed in southern Chile. The overall goal of this project is to relate E. coli antimicrobial resistance and virulence profiles among dairy farms, wastewater treatment plants, and surface waters in a rural watershed.

Methods: Samples were collected over three years in the Valdivia province of Chile. In Year 1, isolates were collected from cattle (n = 847), wastewater treatment plants (n = 27), and rivers (n = 222). Comparisons of microbial load, antibiotic resistance, and virulence were made among all samples. In Years 2 and 3, samples were collected from surface water samples in 11 of the 12 communities of the province (n = 575 and n = 692, respectively). Distributions of antimicrobial resistance and virulence profiles were compared among sites. In Year 2, all E. coli isolates were typed with Box-PCR, and genetic diversity was assessed among sites.

Results: In Year 1, the microbial load in the surface water samples was highest near the wastewater treatment plants. E. coli isolates from the river water samples had different antimicrobial resistance profiles than the cattle isolates. Shiga toxin virulence genes were detected only in the cattle isolates. In Years 2 and 3, isolates immediately downstream from the wastewater treatment plants had more resistance than those immediately before the plants. No shiga-toxin virulence genes were detected. Genetic diversity was most variable among communities sampled, but there was considerable variation among sites within communities as well.

Conclusions:E. coli isolates from surface waters in this study area had a diversity of antimicrobial resistances. In general, the surface water isolates had resistance profiles that were more similar to the wastewater treatment plant isolates than to the cattle isolates. Virulence genes were only detected in the cattle isolates. These data raise questions about the relative importance of different potential contaminating sources to the surface waters in this area. In addition, the high genetic diversity that was observed among communities suggests that the sources of the E. coli might be very local and not spread broadly among the surface waters of the province. Overall, these data will assist in the development of public health interventions in rural communities.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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