Environmental Reservoirs for Enterotoxigenic <i>Escherichia coli</i> in South Asian Gangetic Riverine System

Forecasting diarrheagenic <i>E. coli</i> contamination of aquatic resources to prevent outbreaks largely depends on rapid and accurate diagnostic testing in a few hours. Real-time PCR is widely used for quick culture-free quantitative enumeration of pathogenic bacteria in environmental samples. In this study, real-time PCR in molecular beacon format was used for detection and culture-free quantitative enumeration of enterotoxigenic <i>Escherichia coli</i> (ETEC) harboring <i>LT1</i> gene in a sewage-impacted south Asian Gangetic riverine system. The quantitative budget for ETEC in surface water was observed to vary significantly (DMRT, <i>p</i> < 0.05) among the sites. Aquatic flora (<i>Eichhornia crassipes</i>, <i>Potamogeton crispus</i>, <i>Potamogeton pectinatus</i>, <i>Ranunculus sceleratus</i>, <i>Polygonum glabrum</i>, <i>Pontederia cordata</i>, <i>Najas indica</i> and strands of <i>Spirogyra</i> spp.) collected between sites 1 and 9 exhibited significant high levels of ETEC in comparison to their representatives collected from pristine area. The level of ETEC harboring <i>LT1</i> gene observed in leafy vegetables cultivated along the banks was in the following order: mint leaves > coriander > spinach > methi leaves. The study suggests that the aquatic flora and cultivated leafy vegetables in the south Asian Gangetic riverine system are environmental reservoirs for enterotoxigenic <i>Escherichia coli</i>.