大肠埃希菌对氨基糖苷类抗生素的耐药谱及其产ESBLs的研究

目的了解临床分离的54株大肠埃希菌对氨基糖类苷类抗生素的耐药谱及产ESBLs情况,分析氨基糖苷类修饰酶AAC(3)-II的检出率及该酶的一些特征。方法采用MIC法测定临床分离的54株大肠埃希菌对7种氨基糖苷类抗生素的耐药谱,用NCCLS推荐的酶抑制剂增强纸片扩散法检测产ESBLs菌株,并通过聚合酶链反应、克隆测序和测定重组菌耐药谱对aac(3)-II基因进行研究。结果54株大肠埃希菌对阿米卡星、庆大霉素、卡那霉素、妥布霉素、链霉素、大观霉素和奈替米星的耐药率分别为14.8%、77.8%、59.3%、66.7%、68.5%、61.1%、22.2%;共检测出产ESBLs菌株34株,占63.0%;aac(3)-II基因在54株大肠埃希菌中检出率为88.5%;质粒转化菌产ESBLs且同时检出aac(3)-II基因。重组菌BL21(DE3)/pET26::aac(3)-II对庆大霉素和卡那霉素有耐药性,对其余5种氨基糖苷类抗生素没有表现出耐药性。结论大肠埃希菌对庆大霉素的耐药率最高,对阿米卡星的耐药率最低;耐氨基糖苷类抗生素的大肠埃希菌与其产ESBLs有相关性;重组菌BL21(DE3)/pET26::aac(3)-II仅对庆大霉素和卡那霉素产生耐药。

Research on aminoglycoside resistance profiles and producing ESBLs in 54 strains of Escherichia coli

Objective To investigate the aminoglycoside resistance profiles and producing ESBLs of clinical Escherichia coli strains and analyze the characteristic of AAC(3)-II.Methods MIC tests of 7 aminoglycosides and ESBLs confirmation tests were performed 54 strains of E.coli aac(3)-II gene was amplified by PCR and cloned into pET26b,then and sequenced.Activity of AAC(3)-II was tested by MIC method.Results The resistant rates of 54 strains of E.coli to amikacin,gentamicin,kanamycin,tobramycin,streptomycin,spectinomycin,netilmicin were 14.8%,77.8%,59.3%,66.7%,68.5%,61.1%,22.2% and 63.0%(34/54) of strains were found producing ESBLs.The positive rate of aac(3)-II gene was 88.5%(45/54).The aac(3)-II gene resistance to gentamicin and kanamycin,but not other 5 aminoglycosides.Conclusions Fifty-four strains of E.coli had the highest resistant rate to gentamicin while had the lowest resistant rate to amikacin.ESBLs-producing strains were mostly in aminoglycoside-resistance E.coli.The aac(3)-II gene only mediates resistance to gentamicin and kanamycin.