MICROBIOLOGY AND FOOD SAFETY Prevalence and characteristics of Salmonella isolates recovered from retail raw chickens in Shaanxi Province, China

Abstract In this study, we evaluated the prevalence of Salmonella in retail raw chickens in Shaanxi Province, China on a monthly basis. Additionally, we studied the antibiotic susceptibility, serotype, and genotype of Salmonella isolates and explored their relationships with sampling time, location, market type, and chicken type. The results showed that Salmonella was more prevalent in chickens sampled during the spring and summer than during the autumn and winter. Thirty-nine serotypes were identified from 406 Salmonella isolates, of which Salmonella Typhimurium (16.7%) was the most prevalent. Other prevalent serotypes included S. Thompson (12.8%), S. Essen (9.1%), S. Infantis (6.9%), S. Rissen (5.7%), and S. Enteritidis (5.4%). Approximately 71.4% of the 406 isolates were resistant to three or more antibiotics, 11.8% to 12 or more, and 1.7% to all 14 antibiotics tested. The most frequently detected resistance was to trimethoprim/sulfamethoxazole (82.0%), followed by nalidixic acid (71.9%) and tetracycline (59.4%). The frequencies of resistance to ampicillin, chloramphenicol, and amoxicillin/clavulanic acid were moderately high (∼50% each). Resistance to kanamycin, ceftiofur, streptomycin, gentamicin, and ciprofloxacin were less common (