Lu, Yingyun, Sun, Peng, Shao, Wangfeng, Yang, Cheng, Chen, Lingxiao, Zhu, Aihua, and Pan, Zhiming
Virulence genes expressed in Salmonellaare a primary contributing factor leading to the high morbidity and mortality of salmonellosis in humans. The pathogenicity of Salmonellais mainly determined by the specific virulence factors that it carries. These factors also confer greater virulence and play a role in infection of a host and transmission of disease, and most Salmonella entericacan cause cross-infections between humans and animals. In this study, 265 samples in total were collected from a farmer's market and two supermarkets in Xuzhou, Jiangsu province, China, including 205 pork samples and 60 chicken samples. The suspected Salmonellaisolates were isolated and identified using microbiological and molecular methods, and the confirmed isolates were used for serovar analysis and antimicrobial susceptibility testing. The virulence genes of Salmonellapathogenic islands (SPIs) and Salmonellavirulence plasmids (Spv) in Salmonella-positive isolates were subsequently detected. Salmonellawas isolated from 29.0% of samples, and all isolates were confirmed by PCR targeting the stngene. Among the Salmonellaisolates, resistance was most frequently observed against ciprofloxacin (84.4%), followed by tetracycline (71.4%) and streptomycin (68.8%). Resistance to amoxicillin–clavulanic acid (6.3%) and aztreonam (5%) was less commonly detected. The presence of the following virulence genes was determined by specific PCRs: hilA(SPI-1), sifA(SPI-2), misL(SPI-3), siiE(SPI-4), sopB(SPI-5), and spvC. The detection rate for SPI-1 to SPI-5 was 93.5, 87.0, 97.4, 97.4, and 97.4%, respectively. In addition, the detection rate of the spvCgene was 96.1%. Except for sopB(94.7%), all isolates of the dominant serovar S. entericasubsp.. entericaserovar Enteritidis contained all virulence genes from SPI-1 to SPI-5. This study demonstrated the epidemiological status of Salmonellain raw meat products in Xuzhou, and the complex antibiotic resistance and high isolation rate of virulence genes observed reveal many potential risks of which the findings presented herein will provide orientation to improve public health safeguards.