耐左氧氟沙星大肠埃希菌对氨基糖苷类药物的耐药性研究

目的探讨耐左氧氟沙星(LVX)大肠埃希菌对氨基糖苷类药物的耐药表型与基因型的相关性。方法用纸片扩散法测定75株大肠埃希菌对LVX和6种氨基糖苷类药物的耐药率,PCR法检测6种氨基糖苷类修饰酶基因。结果 49株(65.33%)对LVX耐药,耐LVX菌株对庆大霉素、卡那霉素、链霉素、妥布霉素、奈替米星、阿米卡星的耐药率分别为:73.47%、65.31%、61.22%、51.02%、16.33%、14.29%;与非耐LVX菌株比较,庆大霉素、卡那霉素、妥布霉素耐药率的差异均有统计学意义(P0.05);多药耐药表型的差异同样具有统计学意义(P0.05);耐LVX菌株aac(3)-Ⅱ、aac(6′)-Ⅰ、ant(3″)-Ⅰ、ant(2″)-Ⅰ、aac(3)-Ⅰ,aac(6′)-Ⅱ的检出率分别为:53.06%、46.94%、14.29%、8.16%、4.08%、0;与非耐LVX菌株比较aac(6′)-Ⅰ检出率的差异有统计学意义(P0.05)。结论耐LVX菌株多表现为同时对多种氨基糖苷类药物耐药,提示耐LVX大肠埃希菌对氨基糖苷类药物的耐药与氨基糖苷类修饰酶存在一定相关性,尤以AAC(6′)-Ⅰ为明显。

Drug Resistance Analysis of Levofloxacin-resistant Escherichia coli to Aminoglycosides

OBJECTIVE To detect the dependability of drug-resistant phenotypes and genoypes of levofloxacinresistant Escherichia coli to aminoglycosides.METHODS The antibiotic susceptibility tests of 75 E.coli strains to levofloxacin and six kinds of aminoglycosides drugs were performed by Kerby-Bauer disk diffusion method,then six kinds of aminoglycoside-modifying enzyme genes in these strains were amplified by PCR and their products were sequenced.RESULTS Forty-nine strains(65.33%) were resistant to levofloxacin.The resistant rates of levofloxacin-resistant strains to gentamicin,kanamycin,streptomycin,tobramycin,netilmicin,and amikacin were 73.47%,65.31%,61.22%,51.02%,16.33%,and 14.29%,respectively.The resistant rates of LVX-resistant strains to gentamicin,kanamycin and tobramycin were higher than non-LVX-resistant strains.LVX-resistant strains were multidrug resistant to aminoglycosides.The rates of LVX-resistant strains to aac(3)-Ⅱ,aac(6')-Ⅰ,ant(3")-Ⅰ,ant(2")-Ⅰ,sac(3)-Ⅰ,and aac(6')-Ⅱ were 53.06%,46.94%,14.29%,8.16%,4.08%,and 0,respectively.The rate of LVX-resistant strains to aac(6')-Ⅰ was higher than non-LVX-resistant strain.CONCLUSIONS Levofloxaein-resistant E.coli strains are multidrug-resistant to aminoglycosides.The resistance of LVX-resistant E.coli strains to aminoglycosides is associated with aminoglyeoside-modifying enzymes,especially AAC(6')-Ⅰ.