耐药大肠埃希菌氨基糖苷类修饰酶和16S rRNA甲基化酶基因的分析

目的：了解耐药大肠埃希菌（drug-resistant Escherichia coli,DR-ECO）氨基糖苷类修饰酶和16S rRNA甲基化酶基因的分布,探讨该菌对氨基糖苷类药物耐药的分子机制。方法：采用PCR法检测20株DR-ECO中15种氨基糖苷类修饰酶基因和7种16S rRNA甲基化酶基因,并用PCR直接全自动荧光法对阳性产物进行测序。结果：20株DR-ECO中,18株检出氨基糖苷类修饰酶基因;其中,aac（3）-Ⅱ、aac（6＇）-Ⅰb、ant（3″）-Ⅰ、aadA4/5和aph（3＇）-Ⅰ的阳性检出率分别为25%、25%、5%、65%和55%;只有1株检出rmtB型16S rRNA甲基化酶基因,阳性率为5%,其余基因型均未测出。结论：本组DR-ECO对氨基糖苷类药物的耐药主要与aadA4/5和aph（3＇）-Ⅰ等氨基糖苷类修饰酶基因相关,而与16S rRNA甲基化酶基因无明显关系。

Analysis of aminoglycoside modifying enzyme genes and 16S rRNA methylase genes in drug-resistant Escherichia coli strains

Objective： To analyze aminoglycoside modifying enzyme genes and 16S rRNA methylase genes in drug-resistant Escherichia coli（DR-ECO） strains,and investigate the aminoglycoside resistance mechanisms.Methods： The expressions of aminoglycoside modifying enzyme genes and 16S rRNA methylase genes in 20 DR-ECO strains were assayed by polymerase chain reaction（PCR）;and positive PCR products were sequenced by PCR direct automated fluorescence method.Results： In the 20 DR-ECO strains,18 strains expressed aminoglycoside modifying enzyme genes,the positive rate of aac（3）-Ⅱ,aac（6＇）-Ib,ant（3″）-I,aadA4/5 and aph（3＇）-I were 25%,25%,5%,65% and 55%,respectively,only 1 strains expressed rmt-B type 16S rRNA methylase gene,the positive rate was 5%,and the rest genes expressions were not detected.Conclusion： The aadA4 /5 and aph（3＇）-I,not 16S rRNA methylase gene,were closely related with the DR-ECO aminoglycoside resistance.