Molecular biological characteristics of Staphylococcus aureus isolated from food

A survey was conducted to detect the distributing situation of Staphylococcus aureus in 6 kinds of food and the molecular biological characteristics of the isolates, so as to provide theoretical basis for our food risk monitoring. A total of 205 samples of 6 kinds of food were collected and examined for S. aureus. The GB 4789-2010 (food hygienic inspection method of China), mini VIDAS auto analysis, KB method and pulsed-field gel electrophoresis (PFGE) method were used to detect S. aureus, enterotoxin, drug sensitivity and homology analysis, respectively. The positive rates of S. aureus in the 205 samples were 15.6 % (32 samples), and the positive rates in raw milk were highest (30.0 %), with raw meat and aquatic products next and third (25.0and 12.0 %), cooked meat and milk products (10.0 % and 7.5 %, respectively). No S. aureus was detected in ice creams. With shock culturing in 37 A degrees C for 24 h, 14 strains (43.7 %) produced enterotoxin in the 32 strains of S. aureus. In the drug sensitive tests, in the 32 isolates, 87.5 % were resistant to penicillin; 84.4 % were resistant to ampicillin; 26 (81.3 %) were resistant to tetracycline; 20 (62.5 %) showed resistance to erythromycin. All of the 32 strains were sensitive to trimethoprim sulfamethoxazole, oxacillin, cefoxitin, gentamicin, and vancomycin. No methicillin-resistant S. aureus was isolated from our food samples. PFGE typing showed that S. aureus genotypes profile had significant difference between the strains, indicating diversity contamination of foodborne S. aureus.