Mutant prevention concentration of fluorquinolones against klebsiella pneumoniae

Objective To determine the mutant prevention concentration(MPC)in vitro of Fluorquinolones fagainetor the clinical klebsiella pneumoniae,and guide the clinical rationable use of the agents.Methods The minimal inhibitory concentrations(MIC)of Gatifloxacin,Levofloxacin,Lomefloxacin and Ciprofloxacin against klebsiella pneumoniae were determined by agar 2 fold dilution method.MPC were determined by agar 2 fold dilution with bacterial population inocubated 12×1010CFU,and were defined as the lowest drug concentrations that prevented recovery of colonies.Results The MIC90 of Gatifloxacin,Levofloxacin、Lomefloxacin and Ciprofloxacin were 0.5,4,8 and 4 mg/L respectivly.Gatifloxacin showed the highest antimicrobial activity,it's sensitive was 91.3%.The sensitive of Levofloxacin、Lomefloxacin and Ciprofloxacin were 82.6%,70%and 52%respectivly.The MPC for 90%of isolates(MPC90)of Gatifloxacin and Levofloxacin were 16 mg/L,the MPC90 of Lomefloxacin and Ciprofloxacin were 64 mg/L and 32 mg/L respectivly.Conclusion Gatifloxacin demostrate higest activity against klebsiella pneumoniae.however,combined with pharmacokinetic parameters,the serum concentrations of the four agents were all between MIC and MPC,which suggested the agents could not restrict the selective enrichment of resistant mutants while being used alone.