Multidrug resistance, extended-spectrum β-lactamase (ESBL) production, and colistin resistance in Escherichia coli from retail chicken meat in fresh markets in Bangkok, Thailand

Contamination of chicken meat with antimicrobial-resistant bacteria, particularly multidrug-resistant (MDR), colistin-resistant, and extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli), threatens its safety for human consumption. This study was conducted to determine the prevalence and antimicrobial resistance (AMR) profiles, particularly ESBL production and colistin resistance in E. coli isolated from retail chicken meat in fresh markets in Bangkok, Thailand. A total of 200 (81.6%) E. coli isolates were recovered from 245 chicken meat samples collected from fresh markets across six regions of Bangkok. Among the isolates, 189 (94.5%) exhibited resistance to at least one antimicrobial agent tested, with the highest resistance observed for ampicillin (83.5%), followed by tetracycline (82.5%). Notably, 79.0% of the isolates were classified as MDR. Furthermore, ESBL production and colistin resistance were detected in 2% (n=4) and 4.5% (n=9) of the isolates, respectively. Among the AMR genes investigated, blaTEM-1 was the most frequently detected (61.5%, n=123), followed by mcr-1 (3%, n=6), blaCTX-M-14 (1%, n=2), blaCTX-M-55 (0.5%, n=1), and mcr-3 (0.5%, n=1). Multilocus sequence typing (MLST) analysis of ESBL-producing and colistin-resistant E. coli isolates (n=13) identified seven distinct sequence types (STs), with ST162 (n=2) and ST209 (n=2) being the most prevalent. These findings indicate that retail chicken meat may serve as a potential reservoir of MDR, colistin-resistant, and ESBL-producing E. coli, posing a potential risk of transmission to humans through the food chain. Strengthening surveillance and implementing a One Health approach are essential to mitigate this emerging public health threat.