Counts, Serotypes, and Antimicrobial Resistance of Salmonella Isolates on Retail Raw Poultry in the People's Republic of China

Abstract

The objective of this study was to determine Salmonella counts, serotypes, and antimicrobial resistance profiles in retail raw chicken meat in the People's Republic of China. Salmonella counts were determined according to the most-probable-number (MPN) method for 300 whole chicken carcasses. These samples were collected from large, small, and wet (open) markets in Guangdong, Shaanxi, and Sichuan provinces. Salmonella isolates were serotyped and tested for antimicrobial susceptibility. Of the 300 chicken carcasses, 43.3% were positive for Salmonella, with an overall mean of 1.7 log MPN per carcass (95% confidence interval, 1.6 to 1.8 log MPN per carcass). No significant differences (P > 0.05) were detected for storage temperature (i.e., chilled, frozen, or ambient), market type (large, small, or wet), province, or location (capital or noncapital city). Seventy-eight serotypes were identified among the 1,094 Salmonella isolates. The top five most common Salmonella serotypes on raw chicken carcasses were Enteritidis (19.2%), Indiana (15.2%), Typhimurium (14.6%), Agona (7.1%), and Thompson (6.6%). Salmonella isolates (n = 779) were most frequently resistant to sulfisoxazole (74.1%) and tetracycline (71.1%) and least resistant to ceftriaxone (22.5%) and cefoxitin (19%). Only 4% of the isolates were susceptible to all 15 antimicrobial agents, 45% were resistant to 1 to 5 agents, 29% were resistant to 6 to 10 agents, and 22% were resistant to 11 to 15 agents. Our findings revealed that Salmonella contamination was common in retail raw poultry in China, and the counts on contaminated carcasses were mostly low. Salmonella isolates were diverse in their serotype distribution and antimicrobial susceptibility profiles, with more than half of the isolates resistant to more than five antimicrobial agents. These data may be used in risk assessment models to reduce the transmission of Salmonella via chicken meat to humans in China.