Study on Mutant Prevention Concentrations of Fluoroquinolones Against Salmonella Isolated from Swine

To deve1op strategies for reducing drug resistance development and provide rational application guidelines for available antibacterial medicines in clinic practice,the minimal inhibitory concentrations(MIC) and mutant prevention concentrations(MPC) of ciprofloxacin,levofloxacin,gatifloxacin,enrofloxacin and Gemifloxacin were determined in 56 strains of Salmonella isolated from swine by agar two-fold dilution method.The values of MIC90,MPC90 and MPC/MIC were calculated.The result showed that the order of MPC90 was ciprofloxacinenrofloxacingemifloxacin =levofloxacingatifloxacin.Based on published data for the various fluoroquinolone pharmacokinetic parameters,the time(T) of the serum drug concentrations remained above the MIC90 in a rank order as follows: gatifloxacinlevofloxacingemifloxacinenrofloxacinciprofloxacin.For TMPC90,gatifloxacin would be approximately 24 h and levofloxacin would be approximately 6 h.But other three fluoroquinolones did not exceed the MPC90.The ability of mutant prevention concentration of gatifloxacin and levofloxacin were superior than that of other three fluoroquinolones,which can be firstly selected for treating Salmonella infection.