Molecular characterization of multidrug-resistant and extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolated from Sonali chicken meat in Bangladesh

Antimicrobial resistance (AMR) is a growing global public health concern, with contamination of poultry meat by multidrug-resistant and extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) posing serious risks to food safety and public health. Therefore, this study aimed to isolate and characterize the multidrug-resistant E. coli harboring β-lactam resistance genes from raw Sonali chicken meat samples collected from retail poultry shops across six upazilas of the Narsingdi district in Bangladesh. A total of 390 meat swab samples were collected and analyzed between July and December 2023. E. coli was detected in 68.21% of the isolates, with 7.89% classified as enteropathogenic E. coli (EPEC) and 92.11% as non-EPEC. Antimicrobial susceptibility testing by disc diffusion method revealed complete resistance to ampicillin (100%), with high resistance to erythromycin (87.59%) and third-generation cephalosporins. Furthermore, the lowest resistance was observed for amoxicillin-clavulanate (3.01%). ESBL production was identified in 41.73% of the isolates. On the other hand, non-EPEC strains showed a significantly higher prevalence of ESBL production (p < 0.05). Genotypic analysis of β-lactamase genes in ESBL-positive isolates demonstrated that blaTEM (63.06%) and blaCTX-M-2a (60.36%) were the most prevalent. Additionally, co-occurrence of multiple β-lactamase genes was observed in 54.95% of isolates, with blaTEM, blaCTX-M-2a, and blaOXA-1 being the most common combination. Furthermore, resistance genes for AmpC (blaCMY, 27.07%) and metallo-β-lactamase (blaNDM-1, 9.02%) were exclusively detected in non-EPEC isolates. Significant positive correlations were observed among β-lactamase genes, highlighting the complexity of resistance mechanisms. Our results demonstrate the necessity of judiciously using antibiotics in Sonali chickens to prevent the emergence of resistant bacterial strains.