Enumeration and characterization of campylobacter species from retail chicken carcasses in Beijing, China

Epidemiological data have implicated contaminated raw or undercooked chicken as primary vehicles of Campylobacter transmission to humans. Risk assessment relating to Campylobacter contamination of poultry products in China is frequently hampered by the lack of quantitative data. In this study, whole chicken carcasses (n=240) were collected from the retail markets of Beijing. The level of Campylobacter contamination was enumerated by the plate-counting method. The representative Campylobacter isolates were characterized for antimicrobial resistance. Selected representative isolates were further analyzed by the multilocus sequencing typing method for genetic relatedness. Overall, 26.3% (63/240) of the retail whole chicken carcasses were contaminated by Campylobacter, and the values ranged from 2.5 to 7050 colony-forming units (CFU)/g. The 50th percentile of Campylobacter value was 45 CFU/g in chicken carcass. Multidrug-resistant profiles were observed in 33 (39.2%) C. jejuni isolates (from 27 chicken carcasses) and 57 (86.4%) C. coli isolates (from 30 chicken carcasses). One dominant ST (ST6322) and one dominant clonal complex (CC828) consisting of multidrug-resistant C. coli isolates were identified. Our findings showed a high prevalence of Campylobacter contamination in retail chicken carcasses, which could be a source of exposure to multidrug-resistant isolates for consumers. This study provided baseline enumeration data for the quantitative risk assessment and evaluation of new control measures of Campylobacter contamination in retail chicken products in China.