Isolation and antimicrobial susceptibilities of Staphylococcus aureus in commercially available raw pork in Guangzhou

The contamination situation, molecular typing and resistance characteristics of Staphylococcus aureus from pork were investigated. S. aureus were separated and identified according to GB 4789.10-2010, MLST method was used for molecular classification, drug susceptibility was tested by disc diffusion assay, and the class one integron, integrated gene cassettes and MRSA were examined by PCR. A total of 110 samples were examined and 34 of which (30.9%) were positive for S. aureus. All strains were divided into seven kinds of STs type, namely ST6 (1/34), ST7 (16/34), ST9 (9/34), ST59 (1/34), ST239 (4/34), ST2259 (2/34), and one new ST typing. All 34 S. aureus isolates were resistant to penicillin, and the drug resistant rate of tetracycline, trimethoprim, erythrocin, clindamycin, were 88.2%, 76.5%, 64.7%, 61.8%, respectively. 38.3% (13/34) of S. aureus were MRSA, 5 S. aureus isolates were observed as class one integron, and 2 isolates carried integrated gene cassettes. The results showed that raw pork were severely contaminated with S. aureus, and the isolates had serious antimicrobial resistance phenomenon, ST7 was the main sequence typing, the class one integron were existed in foodborne S. aureus, and the integrated gene cassettes played a role in resistant mechanism of isolates.