产ESBLs大肠埃希菌整合子及其相关基因盒的研究

Study on integrons and integrated gene cassettes in ESBLs-producing strains of Escherichia coli

目的检测产超广谱β-内酰胺酶(ESBLs)大肠埃希菌中整合子的整合酶及插入的相关基因盒情况,分析整合子对细菌耐药性的影响。方法采用K-B琼脂扩散法对45株临床分离的产ESBLs大肠埃希菌进行药敏试验;应用PCR法检测45株产ESBLs大肠埃希菌Ⅰ类、Ⅱ类和Ⅲ类整合子;对Ⅰ类整合子阳性菌进行整合子相关基因盒检测。结果45株菌中有27株(60.0%)含有Ⅰ类整合子,没有检测到Ⅱ类和Ⅲ类整合子阳性菌。在Ⅰ类整合子阳性菌中,有23株携带Ⅰ类整合子相关基因盒(85.2%),5种不同的基因盒图谱,片段大小在600～2322bp,分离自同一科室的部分菌株携带大小相同的基因盒;Ⅰ类整合子阳性菌株的耐药率高于整合子阴性的菌株。结论Ⅰ类整合子及整合子相关基因盒在产ESBLs大肠埃希菌株中分布广泛,整合子在细菌耐药中发挥作用。

Objective To examine the integrons and integrated gene cassettes in ESBLs-producing strains of Escherichia coli,and analyze its influence on the bacterial drug-resistance. Methods Kirby-Bauer susceptibility method was used to analyze the 45 clinically isolated strains of ESBLs-producing Escherichia coli;PCR amplification using specific primers was performed to screen intⅠ1 ,intⅠ2 ,intⅠ3 and integrated gene cassettes from the intⅠ1 positive strains. Results It was found that among these 45 strains of ESBLs-producing Escherichia coli ,27 strains （60.0%） were positive for intⅠ1, none was positive for intⅠ2 and intⅠ3. Further more, among the 27 intⅠ positive strains ,23 strains （85.2%） carried integron intll with integrated gene cassettes, five different gene cassettes were detected, their length between 600 bp and 2322 bp, and the same strains from same division yielded the identically sized amplicons. The antibiotic resistance of the integron-positive strains was higher than that of the integron-negative strains. Conclusions Class 1 integrons and integrated gene cassettes are prevalent among ESBLs-producing strains of Escherichia coll. Integrons are definite influence on the development of antibiotic.