正常人肠道乳酸杆菌耐药性及质粒图谱分析

Analyses of Antibiotic Susceptibility and Plasmid Profile of Normal Human Intestinal Lactobacillus

目的了解正常人肠道乳酸杆菌对临床常用抗生素的耐药水平,研究质粒在乳酸杆菌中的存在频率,分析细菌质粒与耐药谱之间的关系。方法用微量肉汤稀释法测定正常人肠道乳酸杆菌对抗生素的敏感性;分析细菌的质粒图谱,进行质粒消除实验和稳定性实验。结果正常人肠道乳酸杆菌对万古霉素的耐受性最强,其次是环丙沙星和左氟沙星;对庆大霉素、四环素、头孢呋辛和头孢唑啉表现出不同程度的耐受,对青霉素、氨苄西林、利福平、红霉素和罗红霉素较敏感。所有试验菌株均存在多重耐药情况,且有随宿主年龄增加而增加的趋势。93%的菌株含有质粒。经连续传代,4株菌的质粒丢失,致使菌株对庆大霉素和头孢菌素敏感性增加,与其消除质粒后的药敏结果一致。结论正常人肠道乳酸杆菌具有较强的耐药性,多重耐药性较严重,且和年龄有一定相关。大多数菌株都含有质粒,其中5.8kb大小的质粒可能与乳酸杆菌对庆大霉素和头孢菌素的耐受性相关。

Objective To investigate the level of lactobacillus, the existence frequency of plasmid in bacterial antibiotic resistance in normal human intestinal strains, and the relationship between the plasmid carried by the strains and the antibiotic resistance profile. Methods The minimum inhibitory concentration （MIC） was determined by microbroth dilution technique. The plasmid profile of all strains was examined and the stability of plasmids were investigated. Results The antibiotic resistances of the intestinal lactobacillus strains were strong for ciprofloxacin, levofloxacin and vancomycin, among which it was the strongest for vancomycin. Most bacterial strains were tolerant to levofloxacin, gentamycin, tetracycline and ciprofloxacin, but susceptible to low concentration of rifampicin, penicillin and ampicillin. The multiple drug resistance （MDR） was existing in all the tested strains, and getting more severe with the increase of bacterial host age. 93% of lactobacillus strains contained plasmids. After cultured for many times, 4 bacterial strains lost some of plasmids and also, at the same time, lost the drug resistance to gentamycin and cephalosporin. This result was consistent with the that of plasmids eliminated. Conclusion The antibiotic resistance and MDR of the lactobacillus strains in are very severe and correlated with people＇s age. Most of bacterial strains contain plasmids. There may be a correlation between 5.8kb plasmid and the resistance of strains to gentamycin and cephalosporin.