The Distribution And Expression Of Staphylococcus Aureus Toxin Gene

Every year, many cases caused by Staphylococcus aureus are reproted.Currently, theresearch are mainly focus on the toxicity mechanism, while the study of distribution andvirulence genes of Staphylococcus aureus in food are few. So there is no basis for pollutionsource tracing by Staphylococcus aureus in food. We have collected kinds of food samplesfrom Baoding and Shijiazhuang region. The Source of Staphylococcus aureus in the foodare analysed and the distribution law in food are studied. The toxin gene of Staphylococcusaureus was detected out in all kinds of samples by PCR.Then the main virulence gene willbe detailed studied, and the genotype classification of Staphylococcus aureus will be sure.The relationship of toxin genotype and food source environment will be explained andstudy the strength of virulence of different genotypes. Finding the distribution of differentStaphylococcus aureus genotypes will provide the basis for preventing, monitoring andtracing the epidemiology of Staphylococcus aureus in the food. The expression ofStaphylococcus aureus virulence genes was studied and we analysed the difference ofvirulence gene, then determined virulence of Staphylococcus aureus in food.Staphylococcus aureus was isolated and identified by the physiologic and biochemicaltests from799samples, which included raw milk, raw meat (pork, beef, mutton, chicken),meat products, aquatic products, frozen food, fruits and vegetables, bean products and soon. The total detection rate of Staphylococcus aureus was22.2%. There was a significantdifference in detection rate of Staphylococcus aureus among all the food samples, thedetection rate of Staphylococcus aureus in pyogenic tissue and haircut appliances washigher than in the others, it was showed that pollution of Staphylococcus aureus wasserious, the pollution Staphylococcus aureus of was higher in the animal protein than in theplant protein. There are two ways of pollution, one is material contamination, the other isby processing.The distribution of different virulence genes in Staphylococcus aureus was different inthe same food, and the distribution of the same toxicity gene in different foods was alsodifferent. Its distribution was effected by the external environment condition, such nutritioncondition, temperature and so on. The transcription of toxin genes of Staphylococcus aureus strain growing in nutrientbroth culture was studied. In the same culture conditions, toxin expression are different indifferent strains, the expressing of the same toxin in different strains are different too. Theexpression of enterotoxin U, β-hemolysin, γ-hemolysin toxin gene is not consistent withother toxin gene for the report.