Prevalence of ARGs in poultry-associated E. coli in Zhejiang Province, China: A genotypic survey.

Antimicrobial resistance (AMR) in food animals is a pressing global One Health concern. Poultry farming in China's Yangtze River Delta, exemplified by Huzhou City, involves substantial antibiotic use, yet the resultant resistance burden requires characterization. This study quantified clinically relevant antibiotic resistance genes (ARGs) in E. coli from poultry farms across Zhejiang Province, China. We found that all 106 isolates harbored at least one ARG, with 99% exhibiting multidrug resistance. Notably, detections of last-resort resistance genes (e.g., mcr) were made. Isolates from the major hub, Huzhou, carried a higher ARG burden than those from other regions, and mobile genetic elements were associated with ARG co-occurrence. The findings suggest the presence of antibiotic selection pressure within this system and a concerning burden of ARGs in poultry-associated E. coli, with potential implications for environmental and public health. This work highlights the urgent need for integrated interventions, including antibiotic stewardship and surveillance, to mitigate zoonotic AMR risks.