59株大肠杆菌中整合子的研究

目的:研究59株耐头孢西丁大肠杆菌整合子的分类、结构及其在介导耐药中的作用。方法:利用多重聚合酶链反应(PCR)方法检测整合酶基因(intI),对其阳性菌株可变区(Int)扩增产物进行测序分析;采用微量稀释法测定22种抗生素对试验菌株的敏感性。结果:59株大肠杆菌中,45株Ⅰ类整合酶基因阳性(76%);所携带的耐药基因盒绝大多数为aadA5和dfr17;仅有2株携带β-内酰胺酶耐药基因盒;整合子阳性组抑菌浓度明显高于阴性组。结论:Ⅰ类整合子广泛地存在于耐头孢西丁大肠杆菌中;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β-内酰胺类耐药方面,不起主要作用。

Study on Integron in 59 Strains of Escherichia Coli

OBJECTIVE： To investigate the classification, structure and inducing drug resistance of integron in 59 strains of cefoxitin-resistant Escherichia coll. METHODS： PCR method was used to detect integrase gene （intI） and product of variable region of positive strain was performed on sequencing. Sensitiveness of experimental strains to 22 kinds of antibiotics was detected with microdilution method. RESULTS： IntI1 was identified in 45 strains （76%） of the 59 strains Escherichia coli. The most drug resistance genes cassettes were aadA5 and dfr17,only 2 strains encoding 13-1actamase drug resistance gene cassettes. The MIC of integron positive groups was statistically significantly higher than negative groups. CONCLUSION： Class 1 integron resided in cefoxi- tin-resistant Escherichia coli widely. The cause of drug resistance of integron positive strain to aminoglycosides, sulfonamides and chloramphenicol is drug resistance gene cassettes. Gene cassettes does not play important role in integron-mediated drug resistance.