Prevalence and Molecular Epidemiology of Extended-Spectrum β-Lactamase-Producing Escherichia coli and Effects of Antimicrobial Use in Multiple Pig Industry Sectors in Korea

Abstract

Background: The spread of antimicrobial-resistant bacteria has close relationships among humans, animals, and the environment, necessitating the implementation of the "One Health" approach. In previous study, the prevalence and molecular epidemiology of extended-spectrum (3-lactamase-producing Escherichia coli (ESBL-EC) were investigated across multiple pig industry sectors in Korea. In this study, animal developmental stages and antimicrobial usage policies on farms were also considered. Methods: A total of 6,288 non-duplicated samples were collected from pig farms, slaughterhouses, and their personnel from three provinces in Korea between 2020 and 2022. Antimicrobial susceptibility and ESBL gene characterization were performed on the samples. Results: Overall, 1,084 ESBL-EC isolates were collected, with positivity detection rates of 24.7%, 23.3%, 12.7%, 3.9%, 17.2% in pigs, workers, the environment, meat, and total samples, respectively. Common ESBL types were blaCTX-M-55 (N = 628), blaCTX-M-15 (N = 204), and blaCTX-M-14 (N =127). Pig-derived E. coli isolates had antimicrobial resistance (AMR) rates of 80.4%, 47.2%, 32.6%, 36.7%, 43.4%, 62.4%, and 72.1% to ampicillin, piperacillin, cefazoline, ciprofloxacin, cotrimoxazole, chloramphenicol, and tetracycline, respectively. AMR rates were lower in the finishing stage pigs than in the lactating stage pigs and tended to decrease during animal development for most antimicrobials. AMR rates were higher in pigfarms with a customary antimicrobial use policy than in those with a low-level antimicrobial use policy. Conclusions: The findings highlight the significance of elucidating AMR networks among humans, animals, and the environment. Prudent antimicrobial usage and continuous AMR monitoring in the pig industry are crucial to safeguard food safety.