产AmpC酶大肠埃希菌中整合子的研究

目的:观察25株产AmpC酶大肠埃希菌中整合子的分类、结构及其在介导AmpC酶基因转移中的作用。方法:采用微量稀释法测定20种抗生素对试验菌株的敏感性。利用多重聚合酶链反应(PCR)方法检测整合酶基因(intI)及其定位,对其阳性菌株可变区(Int)扩增产物进行测序分析。结果:这25株菌对多种抗生素耐药。20株Ⅰ类整合酶基因阳性(80%);所携带的耐药基因盒绝大多数为aadA5和dfr17;未发现携带AmpC基因盒的整合子。结论:Ⅰ类整合子广泛地存在于产AmpC酶的大肠杆菌中;耐药基因盒是整合子阳性菌株对氨基糖苷类、磺胺类药物及氯霉素耐药的主要原因,但对介导AmpC酶基因转移,不起主要作用。

Study on Integron of AmpC Enzyme-producing Escherichia Coli

OBJECTIVE：To investigate the classification,structure and integron-mediated AmpC enzyme gene transfer of integron in 25 strains of AmpC enzymeproducing Escherichia coli. METHODS：Sensitivity of test strains to 20 kinds of antibiotics was tested by microdilution method. PCR and sequencing were performed on test strains to identify integrase gene（intI）and its location,the product of variable region of positive integrons（Int）respectively. RESULTS：Class ⅠintI were indentified in 20 strains （80%）of 25 strains Escherichia coli. The most drug resistance box cassettes were aadA5 and dfr17 and integory encoding AmpC gene cassette was not observed. CONCLUSION：Class Ⅰ integron resided in AmpC enzyme-producing Escherichia coli widely. The cause of drug resistance of integorn to aminoglycosides,sulfonamides,chloramphenicol is drug resistance gene cassette. Gene cassette does not play important role in integron-mediated antibiotic resistant gene transformation.