Prevalence, Virulence Genes, Antimicrobial Susceptibility, and Genetic Diversity of Isolated From Pasteurized Milk in China.

is a common and important food-borne pathogen that can be found in various food products. Due to low-temperature sterilization for a short period of time, pasteurization is not sufficient for complete elimination of in milk, thereby cause severe economic loss and food safety problems. It is therefore of paramount importance to perform risk assessment of in pasteurized milk. In this study, we isolated from pasteurized milk samples in different regions of China, and evaluated the contamination situation, existence of virulence genes, antibiotic resistance profile and genetic polymorphism of isolates. Intriguingly, 70 samples (27%) were found to be contaminated by and the average contamination level was 111 MPN/g. The distribution of virulence genes was assessed toward 10 enterotoxigenic genes (, and ) and one emetic gene (). Forty five percent strains harbored enterotoxigenic genes and 93% isolates contained gene cluster. The positive rate of , and genes were 73, 96, 75, 54, and 5%, respectively. Antibiotic susceptibility assessment showed that most of the isolates were resistant to β-lactam antibiotics and rifampicin, but susceptible to other antibiotics such as ciprofloxacin, gentamicin and chloramphenicol. Total multidrug-resistant population was about 34%. In addition, isolates in pasteurized milk showed a high genetic diversity. In conclusion, our findings provide the first reference on the prevalence, contamination level and characteristics of isolated from pasteurized milk in China, suggesting a potential high risk of to public health and dairy industry.