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

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

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。

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 aminoglycosidc -resistance E. coll. The aac（3）-Ⅱ gene only mediates resistance to gentamicin and kanamycin.