Determination of antimicrobial resistance and virulence gene signatures in surface water isolates of Escherichia coli

To determine the occurrence of Escherichia coli harbouring virulence markers of shiga- or entero-toxins and resistance to antimicrobials in surface waters. Surface water samples were collected at six locations of the river Gomti. E. coli isolates (n = 90) were characterized for their pathogenic potential using polymerase chain reaction to detect virulence genes as well as their sensitivity to antimicrobial agents using disc diffusion methods. In this study, 57·8% of E. coli isolates exhibited resistance to three or more antimicrobial agents. Sensitivity to cephotaxime, gentamicin and norfloxacin was observed in 7·8%, 48·9% and 77·8% of isolates, respectively. Both stx1 and stx2 genes were present in 15·6% of isolates while remaining isolates had either stx1 (17·8%) or stx2 (6·7%). The stx1 gene (33·3%) was more prevalent than stx2 (22·2%). The results indicate that the LT1 and ST1 genes were positive in 21·2% of isolates. The presence of multi-drug resistance and virulence genes in E. coli isolated from surface water being used for domestic and recreational purposes may result in waterborne outbreaks. The data will be useful in monitoring surface waters for forecasting and management of waterborne outbreaks.