产ESBLs肠杆菌科细菌对氨基糖苷类抗生素耐药机制研究

Aminoglycosides resistance mechanisms of extended spectrum β-lactamases-producing Enterobacteriaceae

目的研究产超广谱β-内酰胺酶(ex tended spectrum beta-lactam ases,ESBL s)肠杆菌科细菌对氨基糖苷类抗生素的耐药分子机制。方法采用PCR方法对耐氨基糖苷类抗生素的产ESBL s菌株进行氨基糖苷类耐药机制研究,并同时对钝化酶基因DNA测序,进行网上基因相似性检索。结果20株耐氨基糖苷类的产ESBL s肠杆菌科细菌中存在氨基糖苷钝化酶基因,分别有aac(3)-I、aac(3)-II、aac(6′)-I、aac(6′)-II、ant(2")-I和aph(3)′-V I,以aac(3)-I、aac(3)-II和aac(6′)-I为主。部分菌株同时可含有多种钝化酶基因。DNA测序分析结果与国外报道已知相应氨基糖苷钝化酶DNA测序结果一致。结论产ESBL s肠杆菌科细菌中普遍存在氨基糖苷钝化酶,四川大学华西医院分离得到的氨基糖苷类耐药的产ESBL s肠杆菌科细菌的钝化酶基因型主要是aac(6′)-I、aac(3)-II、aac(3)-I和ant(2")-I。

Objective To investigate ESBLs-producing Enterobacteriaceae strains. the molecular mechanisms of the aminoglycoside-resistance in Methods The nucleotide sequence of aminoglycoside-modifying enzyme genes in ESBLs-producing plus aminoglycoside-resistant strains amplified by PCR were detected by automatic sequencer, and compared with relative DNA sequencing reported by others in Internet GenBank through Blastx searching. Results Among 20 aminoglycoside-resistant plus ESBLs-producing strains, aminoglycoside-modifying enzyme genes have been found. They were aminoglycoside acetyltransferase （3）-Ⅰ gene [aac（3）-Ⅱ, aminoglycoside acetyltransferase （3）-Ⅱ gene [aac（3）-Ⅱ], aminoglycoside acetyltransferase （6＇）-Ⅰ gene [aac （6＇）-Ⅰ] ＇ aminoglycoside acetyltransferase （6＇）-Ⅱ gene [aac （6＇）-Ⅱ], aminoglycoside adenyltransferase （2＂）-Ⅰ gene [ant （2＂）-Ⅰ] and aminoglycoside phosphoryltransferase （3＇）-Ⅵ gene [aph （3＇）-Ⅵ]. The DNA sequences of aminoglycoside-modifying modifying enzymes genes were in concordance with other aminoglycoside-modifying enzyme genes refered in Internet GenBank. Conclusions Aminoglycoside-modifying enzyme were commonly existed in ESBLs-producing strains of Enterobacteriaceae. The genes encoding aminoglycoside-modifying enzymes were mainly aac（6＇）-Ⅰ, aac（3）-Ⅱ, aac（3）-Ⅰand ant（2″）-Ⅰ.