健康人群大肠埃希菌Ⅰ类整合子与耐药性关系

Relationship between antibiotic resistance and class 1 integron of Escherichia coli isolated from healthy human

目的研究健康人群大肠埃希菌中Ⅰ类整合子携带情况及分子特征,分析其与细菌耐药性关系。方法采用V itek32细菌分析仪和纸片扩散法,检测150株大肠埃希菌抗生素敏感性,PCR检测总DNA中Ⅰ类整合子,扩增产物进行限制性核酸内切酶分析,测序确定携带基因盒种类,脉冲场凝胶电泳对整合子阳性菌株分子分型。结果150株大肠埃希菌中,83株菌耐受＞3种抗生素,耐多药率55.3%;超广谱β-内酰胺酶（ESBLs）阳性5株,阳性率3.3%;携带Ⅰ类整合子42株,扩增子150～3 000 bp,有8种带型;耐药基因盒主要是dfr和aadA类,最常见基因盒排列dfr17～aadA5;整合子分布在不同基因型菌株中。结论健康人携带的大肠埃希菌中广泛存在Ⅰ类整合子,与细菌耐多药性密切相关;分子分型结果提示整合子能在细菌种内水平传播,整合子是介导细菌耐药性的重要分子机制。

Objective To investigate the level and molecular characteristics of class 1 integron in Escherichia coli strain isolated from healthy human of Beijing and to analyze the relationship between antibiotic resistance of Escherichia colt and the class 1 integron. Methods The antirnicrobial susceptibility test of 150 Escherichia coli isolates was performed with Microscan Vitek32 and disk diffusion assay. Class 1 integron was amplified by PCR with total DNA. The purified amplicons of class 1 integron was characterized by RFLP analysis and sequencing. The integron positive isolates were typed by PFGE. Results Eighty-three （ 55.3 % ） isolates were multidrug resistant （ resistance to over 3 antibiotics）. Five isolates （ 3.3 % ） produced ESBLs. Class 1 integron was present in 42 isolates. The size of class 1 integron was form 150 bp to 3 000 bp. Most of the gene cassettes integrated in the integron conferred resistance against trimethoprim and streptomycin-spectinomycin, and integrons with the dfrl7-aadA5 gene cassettes combination were predominant. Class I integron distributed in different genotype Escherichia coli strain isolate. Conclusion There was a good correlation between integron-carrying and the antibiotic resistance of Escherichia coli strains isolated from healthy human in Beijing. Genotyping suggests horizontal intraspecies transfer of integron. Integrons plays an important role in mediation of antibiotic resistance.