Abstract:[Objective]To evaluate the antimicrobial resistance and transmission risk of foodborne Escherichia coli in wet markets, this study isolated E. coli from pork, aquatic products, vegetables, and wastewater collected from three wet markets in Hangzhou, Zhejiang.[Method]The isolates were identified by 16S rRNA sequencing, and their antimicrobial resistance phenotypes were determined via the disk diffusion method. PCR was employed to detect antimicrobial resistance genes and integrons in the isolates. The antimicrobial resistance characteristics of E. coli were analyzed, and conjugation experiments were performed to assess the potential for horizontal transfer of antimicrobial resistance genes. Co-occurrence network analysis was conducted to evaluate the transmission risk of antimicrobial resistance among the isolates.[Result]A total of 68 E. coli strains were isolated from 180 samples. The Kirby-Bauer (K-B) test revealed that most E. coli isolates were multidrug-resistant (MDR). The resistance rates to amoxicillin, tetracycline, and sulfisoxazole exceeded 50%. PCR amplification revealed that the tetracycline resistance gene tetA had the highest detection rate, followed by sul1, blaTEM, and tetB. Moreover, E. coli isolates from the wet market B exhibited higher prevalence of antimicrobial resistance genes than those from wet markets A and C. The detection rate of the integrase gene intI1 was the highest at 30.88%, and eight intI1-positive strains carried gene cassettes. Conjugation experiments demonstrated that in three donor strains, tetA could be transferred via plasmid-mediated conjugation into the recipient strain EC600. Co-occurrence network analysis revealed a strong co-transmission relationship between antimicrobial resistance genes and mobile genetic elements among E. coli isolates.[Conclusion]The author investigates the antimicrobial resistance profiles and dissemination risk of E. coli isolated from three wet markets in Hangzhou, Zhejiang, providing a theoretical basis for ensuring the food safety in wet markets.
