High-risk ARGs in environmental E. coli from the Taihu Lake watershed

The global antimicrobial-resistance crisis is exacerbated by environmental bacterial reservoirs. This work investigated antibiotic-resistance genes (ARGs) carried by E. coli from 118 surface-water samples across the Taihu Lake watershed. We isolated E. coli using mTEC agar and uidA PCR and screened isolates for 92 ARGs covering 15 resistance classes. Samples from Huzhou showed higher ARG detection rates than samples from other regions, with aminoglycoside, sulfonamide, and glycopeptide resistance genes predominant. Urban sampling sites represented ARG hotspots. Co-occurrence analysis revealed associations between quinolone and aminoglycoside resistance genes, suggestive of horizontal gene transfer. Risk assessment categorized 25.3% of samples as high risk. These observations illustrate human-driven ARG pollution in local aquatic environments and support targeted surveillance and One Health-oriented mitigation strategies.