Drug-sensitivity Restoration of Escherichia coli to Ciprofloxacin and Enrofloxacin

To provide a scientific basis for reducing the harm of drug resistance and formulating clinical rotational schedule of antibiotics application,whether subculturing,nutrition factors and resistant bacteria strain D600 would raise E.coli sensitivity to ciprofloxacin and enrofloxacin were investigated by using the methods of single factor test and orthogonal test.The results indicated when continued subcultivation to210 generations,the MIC value of E.coli D600 to ciprofloxacin dropped from 128μg/mL(high-leve resistance)to 32μg/mL(mind-leve resistance),but its MIC value to enrofloxacin not changed.The MIC values of E.coli D600 to two drugs,which was subcultrued 210 times in lower nutrition level of broth,dropped from high-leve resistance(128μg/mL)to sensitivity(ciprofloxacin 0.25μg/mL,enrofloxacin0.5μg/mL).The lower nutrition level of culture medium,the more subcultivation times and lesser proportions of resistance strains,the lower the MIC values of E.coli to the antibiotics were up to be sensitivity.The three factors tested showed certain effect on the drug-sensitivity restoration of E.coli to ciprofloxacin and enrofloxacin,furthermore the effect to ciprofloxacin was stronger than to enrofloxacin.