The Study Of Distribution And Enterotoxin Genes Of Staphylococcus Aureus In Food

Staphylococcus aureus has been considered one of the most important bacteria causing food poisoning, It exist in nature environment far-rangingly and has higher resistance to all kinds of physical and chemical factors. The food poisoning caused by Staphylococcus aureus taked a high proportion in bacterial food poisoning in all countries whether in developed countries or in developing countries. The percentage of food poisoning caused by Staphylococcus aureus is about 33% in America, 45% in Canada, and more than 50% in some Europe countries such as Hungary, Finland, et al. In our country, there are many food poisoning cases caused by staphylococcus aureus.In the test, staphylococcus aureus was isolated and identified by the physiologic and biochemical tests from 510 samples, which included raw milk, raw meat (pork, beef, mutton, chicken), meat products, aquatic products, frozen food, fruits and vegetables, bean products and so on. As a result, Staphylococcus aureus was detected out in seven kinds of samples. The total detection rate of staphylococcus aureus was 21.9%. Therefore, it was proved that food contaminated by Staphylococcus aureus is universal in this region. At the same time, it was showed that pollution level of Staphylococcus aureus in Baoding and circumjacent area was high, so we should give more attention to it. There was a significant difference in detection rate of Staphylococcus aureus among all the food samples,and the detection rate of Staphylococcus aureus in raw milk and frozen food was higher than in the others, which showed that the probability of this bacterium to pollute raw milk and frozen food was high. Therefore, we should attach importance to quality problem of this two kinds of food in order to avoid food-borne diseases breaking out. Besides, some kinds of foods, which have lower detection rate of Staphylococcus aureus, are closely linked with our daily diet. So, sufficient attention should be paid to this hygiene problem of food.The reason of food poisoning caused by Staphylococcus aureus is mainly to eat food that contains staphylococcal enterotoxins. At present, staphylococcal enterotoxins usually can be divided into 14 types (A, B, C, D, E, G, H, I, J, K, L, M, N, O) according to Serological typing, and A type was seen most commonly in fulminant food poisoning In the experiment, primers were designed for SEA, SEB and SEE pathogenic gene of Staphylococcus aureus. Then, PCR identification was employed with primers designed to study distribution of the three enterotoxin genes. Among 295 Staphylococcus aureus strains isolated, 145 strains contains one of enterotoxins SEA,SEB and SEE at least, 58 strains contained SEA, 69 strains contained SEB, 5 strains contained SEE, 12 strains contained both SEA and SEB, and 1 strain contains both SEA and SEE. The study indicated that Staphylococcus aureus separated has high probability of carrying toxin.The pollution situation and epidemioiogic conditions of Staphylococcus aureus in crowd, livestocks and food should be elucidated in further research, which will provide basis for the supervision of Staphylococcus aureus, the detection of explosion and spread as well as tracking pollution sources.