Antimicrobial Resistance in E. coli Isolated from Residential Water Wells in South Central Virginia

Approximately 1.7 million Virginians rely on wells, springs or cisterns for water supply and water safety is of particular concern to them. Additionally, due to wide application of antibiotics for human health and agricultural practices, the emergence of antimicrobial resistant (AMR) bacteria and their presence in the environment is a potential health threat. The presence of AMR bacteria in ground water from private water wells hasn’t been investigated and the risk of encountering AMR bacteria is unknown. The aim of the present study was to evaluate the prevalence and AMR of E. coil in water samples from private wells. Pulsed-field gel electrophoresis (PFGE) profiles of the isolated E. coli were further explored for genomic diversity and environmental association to identify potential pathways of the bacterial transmission with regard to the routes of contamination. A total of 823 water well samples from 10 counties in the South Central region of Virginia were obtained between February, 2016 and March, 2017. E. coli was detected in 3.7% of total samples.. Approximately 3% of the tested E. coli were resistant to at least four antimicrobials. Four isolates were non-susceptible (either resistant or intermediate) to more than seven antimicrobials. No isolates had matching PFGE profiles demonstrating that the isolated E. coli strains had a high degree of genomic diversity. This study clearly demonstrates a potential hazard arising from contaminated water wells and emphasizes the importance of regular water quality monitoring for those relying on private water wells.