Pharmacodynamic investigation of rifampicin , linezolid and glycopeptide antibiotics against methicillin-resistant Staphylococcus aureus

Objective To compare the selective power of anti-drug-resistant mutant of vancomycin , teicoplanin , linezolid and rifampicin to methicillin-resistant Staphylococcus aureus (MRSA) .Methods The minimum inhibitory concentration (MIC) to MRSA was determined by E-test method. Mutant prevention concentration (MPC) was measured by mix-bacterial method (the inoculated bacterial concentration1×1010CFU/mL) .Selection index (MPC/MIC) and the ratio of MPC to target maximum serum concentration (MPC/Cmax) of the four antibiotics were compared.Results MIC values of vancomycin , teicoplanin , linezolid and rifampin against MRSA were 0.5,1.0,0.5and≤0.5μg/mL; MPC values were 51.2, 25.6 , 9.6and 1024.0 μg/mL ; Selection indices were 102.4 , 25.6 , 19.2and2 048.0; MPC/Cmax were 1.28 , 0.57 , 0.64 and107.80 , respectively.Conclusion Linezolid and teicoplanin have narrower mutant selection window than vancomycin and rifampin , and they have obvious advantages in preventing bacterial antibiotic resistance.