低剂量恩诺沙星对SPF小鼠肠道菌群的影响研究

 采用SPF小鼠动物模型研究了低剂量恩诺沙星对肠道菌群细菌数量、细菌耐药性和定植抗力的影响。连续饮水给药（1、10 和100 mg·L-1）48 d后，恩诺沙星对SPF小鼠肠道菌群的主要影响为：10和100 mg·L-1恩诺沙星可抑制部分需氧和兼性厌氧菌的生长（P＜0.05或P＜0.01）；100 mg·L-1恩诺沙星可抑制肠球菌和部分拟杆菌的生长（P＜0.05或P＜0.01）；1、10 和100 mg·L-1恩诺沙星使需氧和兼性厌氧菌对环丙沙星的耐药率增加（P＜0.05或P＜0.01）；100 mg·L-1恩诺沙星使拟杆菌对环丙沙星的耐药率增加；1、10 和100 mg·L-1恩诺沙星可降低部分SPF小鼠肠道菌群的定植抗力，使菌群对外源细菌的屏障作用下降。低剂量恩诺沙星对肠道菌群数量和定植抗力影响不大；恩诺沙星对肠道菌群的主要影响是使需氧和兼性厌氧菌的耐药率增加；中国现行规定的恩诺沙星和环丙沙星的日允许摄入量（ADI）可能也会对人体肠道菌群产生影响，主要为选择出耐药需氧和兼性厌氧菌。

Effects of Low Concentration Enrofloxacin on SPF Mice Intestinal Microflora

In this study, SPF mice model has been developed to study the effects of enrofloxacin on fecal aerobic and anaerobic populations, selection of bacteria resistant to ciprofloxacin, maintenance of the intestinal barrier against exogenous E.coli. Enrofloxacin was administered via drinking water(1, 10 and 100 mg·L-1) to SPF femal mice for 48 d. Total aerobic flora counts, Enterococci counts and Bacteroides counts decreased significantly following exposure to 100 mg·L-1 enrofloxacin. Total aerobic flora counts were also affected by 10 mg·L-1 enrofloxacin. Enrofloxacin exposure at 1, 10 and 100 mg·L-1 increased the percentage of aerobic populations resistant to 1 ?g·ml-1 ciprofloxacin. 100 mg·L-1 enrofloxacin also increased the percentage of Bacteroides resistant to 16 ?g·ml-1 ciprofloxacin. The resistance colonization of some SPF mice was impaired at 1, 10 and 100 mg·L-1 enrofloxacin.The results indicated that enrofloxacin can partly decrease the aerobic populations, but pose little effects on anaerobic populations. In conclusion, the effects of low concentrations enrofloxacin on SPF mice fecal bacteria population and resistance colonization were not significant, the most important impact of low concentrations enrofloxacin on SPF mice intestinal microflora may be resistance selection and increase the percentage of resistant aerobic flora to ciproflxacin. The ADI of enrofloxacin and ciprofloxacin established by Ministry of Agriculture may affect human intestinal microflora by selecting resistant aerobic flora.