Objective:Evaluation the diagnostic accuracies of the automated Vitek 2 system for the detection of oxacillin resistance in Staphylococcus aureus strains.Methods:The susceptibility of Staphylococcus aureus to Oxacillin were determined by AST P535 card and cefoxitin disk diffusion tests.The validity of the two methods were evaluated by compared the results with the gold standard method of mecA gene determining by PCR.Results:The total 125 strains including 89 methicillin resistant Staphylococcus aureus(MRSA) with the positive mecA gene and 36 methicillin susceptive Staphylococcus aureus(MSSA) with the negative mecA gene.Of the 89 MRSA and 36 MSSA strains detected by PCR

81 strains of MRSA and 35 strains of MSSA were correctly detected by AST P535 cards and 87 strains of MRSA and 36 strains of MSSA were correctly detected by cefoxitin disk diffusion tests.The sensitivity and specificity for Vitek-2 AST P535 card and cefoxitin disk diffusion tests were 91%

97.5 and 97.8

100% respectively.Conclusions:Detection of methicillin resistance in Staphylococcus aureus strains by using AST P535 cards have good sensitivity and specificity with satisfactory results to addressing clinical diagnostics.Automated Vitek 2 system combined with cefoxitin disk diffusion tests can further improve the detective accuracies.