Genomic analysis of Campylobacter risk in retail chicken isolated from Beijing in 2024.

This study investigated the prevalence, genetic diversity, antimicrobial resistance, and virulence characteristics of Campylobacter spp. isolated from retail chicken carcasses in Beijing, China. Overall, Campylobacter was detected in 55.88% of samples, with significantly higher contamination in wet markets compared to supermarkets. A total of 106 non-duplicated isolates were obtained, including 59 C. jejuni and 47 C. coli, exhibiting high genetic diversity with 78 sequence types (STs) and 15 novel STs identified. Antimicrobial susceptibility testing revealed universal resistance to fluoroquinolones and high resistance to tetracycline, while multidrug resistance was prevalent, particularly in C. coli. Genotypic analysis identified 34 resistance genes and 4 point mutations, showing generally strong genotype-phenotype correlation, although notable discrepancies were observed, especially for florfenicol and azithromycin. The health risks to humans posed by tetracycline and macrolide-lincosamide-streptomycin (MLS)-associated antibiotic resistance genes (ARGs) should be given priority attention. Virulence profiling demonstrated that C. jejuni harbored significantly more virulence-associated genes than C. coli, including genes linked to Guillain-Barré syndrome, indicating a substantial potential public health risk from contaminated poultry.