Comparison the mutant prevention concentration of 6 kinds of fluoroquinolones for Staphylococcus aureus

Objective To determine the mutant prevention concentration(MPC) of 6 kinds of fluoroquinolones for the clinical isolated Staphylococcus aureus,and to compare the capacity of the choosing on the resistant mutant strain of the 6 kinds of fluoroquinolones.Methods The minimal inhibitory concentrations(MIC) and MPC of ciprofloxacin,levofloxacin,gatifloxacin,caderofloxacin,mixifloxacin and pazufloxacin were determined on 36 strains of S.aureus isolated from clinic which were sensitive to oxacillin and ciprofloxacin by agar two-fold dilution method and ager plates dilution method.Results For MPC,mixifloxacin was the lowest,then caderofloxacin,gatifloxacin,pazufloxacin and levofloxacin,and ciprofloxacin was the highest among the 6 kinds of fluoroquinolones against Staphylococcus aureus.As for MIC90/MPC90,mixifloxacin,caderofloxacin,gatifloxacin and pazufloxacin were more lower,levofloxacin and ciprofloxacin were more higher.The comparison of the pharmacokinetic parameters in vivo to MPC90 for the 6 kinds of fluoroquinolones against the 36 strains of S.aureus showed that MPC90 was less than Cmaxfor moxifloxacin and caderofloxacin.Conclusion Moxifloxacin,caderofloxacin and gatifloxacin have the lower MPC and narrower mutant selective window with a high ability to restrict the selection of S.aureus resistant mutants among the 6 kinds of fluoroquinolones against the S.aureus.