Quantitative Microbial Risk Assessment On Staphylococcus Aureus In Pork In Shanghai

Staphylococcus aureus is a food-borne pathogen widely distributing in nature. It is the top ranking causative bacreria of foodborne illness outbreaks in China and many other countries in the world which has become a worldwide health problem. As main animal foods, pork products are indispensable in Chinese residents' daily dietary. It is easily contaminated by S.aureus because of its abundant nutritional components. So it is necessary to conduct a risk assessment to evaluative the risk associated with pork products contaminated with S.aureus.In this research, a field survey investigated the dietary intake of common pork products and an S.aureus contamination monitoring program of commercial pork products in Shanghai have been carried out. Meanwhile, multiple growth model was used to predict S.aureus growth under storing no more than 24 hours in room temperature for the time period of June through October.The results are as follows:The average consumption of total pork products in Shanghai urban citizens was 107.77g per reference man per day. The average consumption of pig tissues, cooked foods and smoking bacons were 3.99g,10.26g and 9.70g per reference man per day.There were 370 negative samples, account for 92.5%, including 6 samples in which S.aureus were not detected and 364samples in which bacteria number was below the detection limit.30 positive samples were detected at concentrations ranging from 10～6000 cfu/g, of which 27 samples were positive for bacterial counts lower than 1000 cfu/g, occupy 90%. The geometric mean of contaminated level in all 400 samples and positive samples were-0.2998 log cfu/g and 2.169 log cfu/g.The probabilities of occurrence of Staphylococcal food poisoning related to pork intake in June to October were 3.3%,33.6%,21.4%,7.6% and 0.3%. In June, September and September, contamination levels of S.aureus in pork at time of purchase was considered to be the most relative factor of Staphylococcal food poisoning which in July and August was most likely induced by consuming foods with long term storage. The distribution trend of illness probability in related five months was consistent with the temperature, suggesting that the prediction model used in our study is valid.