Purpose: The objective of this study was to identify the antibiotic and disinfectant resistance phenotypes, genotypes, and genetic relatedness of Salmonella isolated from retail meats in China.
Methods: Salmonella isolates were recovered from chicken, beef, and pork purchased from selected supermarket. Antibiotic susceptibility was tested according to the standard disk diffusion method. The MICs of disinfectants were determined using the agar dilution method. All isolates were screened for the presence of disinfectant resistance genes and further analyzed for genetic relatedness by PFGE.
Results: Overall, 50.9% (n = 163) of 320 retail meat samples were contaminated with Salmonella, and 32 different serovars were identified. The predominant serotype was Salmonella Derby (34.8%), followed by Salmonella Enteritidis (12.3%) and Salmonella Rissen (9.0%). Overall, 82.8% isolates were resistant to OTC, 66.3% to TMP, 28.8% to AMX, 23.9% to AMP, 20.3% to LEV, 11.7% to GEN, 11.7% to EFT, 15.3% to CIP, and 3.7% to AMC, respectively. The MICs of the disinfectants cetyltrimethylammonium bromide and cetylpyridinium chloride were 8 - 128 mg/l and 8 - 256 mg/l. The qac and sugE(p) gene was found less prevalent (0.0% to 14.7%). Up to 71 distinct PFGE types were identified among the 163 Salmonella isolates. PFGE revealed that the resistant isolates were associated with the sampling supermarkets or groceries.
Significance: Salmonella can serve as a critical vector in spreading disinfectant and antibiotic resistance. The use of disinfectant in food processing environments may have played a role in the emergence of antibiotic and disinfectant resistant bacteria.