Abstract: AIM: To compare the mutant prevention concentration (MPC) of linezolid and vancomycin against methicillin resistant staphylococcus aureus (MRSA) and study the correlation between minimal inhibitory concentration (MIC) and MPC. METHODS:MICs and MPCs of two drugs against 35 MRSA clinical stains we re determined by agar plates dilution method.The correlations between MIC and MPC were determined by linear regression.The ability to rest rict the resi stance was evaluated according the pharmaco kinetics of two drugs. RESULTS: The MPCs of two drugs against MRSA were 16 and 8 μg/mL and the MPC/MIC was 8.MPCs and MICs correlated poo rly (R 2 were 0.32 and 0.008, respectively).According to pharmacokinetics of two drugs, the concentration of linezolid was inside the MSW (mutant selective window) for the entire dosage interval, while the concentration of vancomycin exceeded the MPC for the most do sage interval. CONCLUSION: The capacity of vancomycin for rest ricting the selection of MRSA resistant mutants is stronger than that of linezolid.There is low correlation between MPC and MIC.

Key words: Linezolid, Vancomycin, Methicillin resistant staphylococcus aureus, Mutantprev ention concentration