Effects of Residual Dose of Enrofloxacin on Intestinal Microflora in SPF Mice

Objective To investigate the effects of residual doses of enrofloxacin on mouse intestinal microflora.Methods Female SPF KM mice received enrofloxacin in a oral doses of 0,0.005,0.05,0.5,5 mg/kg body weight in drinking water for 35 days.Two independent trials of similar design were performed with enrofloxacin.The first trial evaluated the changes of susceptibility of target organisms to enrofloxacin.The second trial evaluated the changes in the barrier effect of the intestinal microflora.Results The resistance rates of total anaerobes and aerobes to enrofloxacin in doses of 0.5 and 5 mg/kg d.were significantly higher than that of the control mice(P0.05 or P0.01).The elimination rate of exogenous Candida albicans was faster and complete in the control group as compared with that in mice treated with 0.5 and 5 mg/kg d.enrofloxacin.Conclusion Changes of balance of the fecal microflora can be induced by enrofloxacin in doses of 0.5 and 5 mg/kg d.Under the experimental conditions of the study,the mouse intestinal microflora are not affected by enrofloxacin in doses of 0.005 and 0.05 mg/kg d.