The convergent threat of ESBL, carbapenemase, and MCR resistance determinants in the Hong Kong food chain: A cross-sectional surveillance study.

The emergence of antimicrobial resistance (AMR) in the food supply poses a significant public health threat. This study investigated the prevalence and molecular characteristics of extended-spectrum beta-lactamase (ESBL)-producing, carbapenemase-producing, and mobilized colistin resistance (mcr)-harbouring bacteria in retail food products in Hong Kong. A total of 710 samples (449 raw meats and 261 ready-to-eat foods) were collected from supermarkets and wet markets. Overall, ESBL-producing bacteria were detected in 49.6% of samples, with highest prevalence in pig organs (100%) and chicken (77%). Carbapenemase-producing bacteria were identified in 20% of samples, with highest prevalence in pig organs (90.5%) and pork (33%). mcr-harbouring bacteria were detected in 20.1% of samples, with highest prevalence in pig organs (71.4%), chicken (33.3%), and sashimi (30.6%). Wet market samples exhibited significantly higher ESBL and carbapenemase positivity than supermarket samples (p < 0.001), whereas mcr prevalence was higher in supermarket chicken. Molecular analysis revealed Escherichia coli and Klebsiella spp. as the predominant ESBL- and carbapenemase-producing organisms, with CTX-M and NDM as the dominant gene families. Notably, multiple mcr variants were identified, with mcr-10 (54%) more prevalent than mcr-1 (44.3%). Co-occurrence of resistance determinants was common, with 23.2% of samples harbouring multiple resistance gene classes, and 6.1% carrying ESBL, carbapenemase, and mcr genes concurrently. These findings highlight the widespread distribution of clinically significant AMR determinants in the Hong Kong food supply, including the first detection of mcr-8, mcr-9, and mcr-10. Enhanced surveillance and targeted interventions are urgently needed to mitigate the dissemination of multidrug-resistant bacteria through the food chain.