Drug susceptibility and molecular epidemiology of Staphylococcus aureus isolated in Changping district of Beijing

Objective To understand the drug susceptibility, virulence genes and molecular epidemiological characteristics of 74 strains of Staphylococcus aureus isolated in Changping district of Beijing from 2011 to 2014, and provide evidence for the control and prevention of food-borne infection caused by S. aureus. Methods The strains were isolated and identified according to GB 4789.10-2010. The resistance to 16 antibiotics was tested with VITEK2 Compact system, －lactamase was detected with specific kit. PCR was used to detect the genes encoding enterotoxin, leukocidin, and heat-stable phosphatase. Pulsed field gel electrophoresis (PFGE) was used for the molecular subtyping of the strains. Results Sixty eight strains (91.89%) were antibiotic resistant, and the resistant rate to penicillin was highest (87.84%),followed by the resistant rates to erythromycin (44.59%) and clindamycin (39.19%). For virulence gene detection, the positive rate of enterotoxin genes was 64.86%, and 35 strains(72.92%)produced 2 kinds of enterotoxin, the positive rate of heat-stable phosphatase was 89.19%; and the positive rate of lukF gene encoding leukocidin was 77.03%. Sixty five strains belonged to 40 PFGE patterns, and 9 strains could not be digested by restricted enzyme. Conclusion The strains of S. aureus isolated in Changping were highly antibiotic resistant, molecular polymorphism was found among them, and detection rate of virulence genes was high, indicating the high risk to cause food borne infection.