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目的:分析泌尿系统感染中大肠埃希菌I类整合子的流行情况和分子特征。方法:应用全自动细菌分析仪M i-croscan W alkAway40和纸片扩散法,对40株大肠埃希菌进行抗生素敏感性测定,PCR扩增细菌总DNA上的I类整合子,对扩增产物进行测序,并分析其中的基因盒,利用脉冲场电泳(PFGE)对菌株进行分子分型。结果:22株细菌含有I类整合子,整合子大小为1 000、1 200、1 700和3 000 bp,22株细菌各含1~2个整合子。1 000 bp整合子含基因盒aadA1,1 200 bp整合子含基因盒dfr1-OFRx,1 700 bp整合子含基因盒dfr17-aadA5,3 000 bp整合子两端分别含基因盒aadB、cm lA1,40株细菌被分为不同的基因型,在不同基因型菌株中发现了相同的整合子。结论:整合子在泌尿系统感染大肠埃希中广泛存在,整合子是介导细菌耐药性的重要分子机制,基因分型结果提示整合子在细菌种内水平传播。
OBJECTIVE: To analyze the prevalence and molecular characteristics of Escherichia coli Class I integron in urinary tract infections. Methods: 40 strains of Escherichia coli were tested for antibiotic susceptibility by using automatic analyzer M i-croscan W alkAway40 and disk diffusion method. Type I integrons were amplified by PCR from total bacterial DNA. The amplification products Sequencing and analysis of the gene cassettes were carried out, and the strains were molecularly typed by pulsed-field gel electrophoresis (PFGE). RESULTS: Twenty-two strains contained type I integrons with integrons of 1 000, 1 200, 1 700 and 3 000 bp in size, and 1 to 2 integrons for each of the 22 strains. The 1 000 bp integron containing the gene cassette aadA1,1 200 bp integron containing the gene cassette dfr1-OFRx, the 1 700 bp integron containing the gene cassette dfr17-aadA5, the 3 000 bp fragment containing the gene cassette aadB, cm1A1, Forty bacteria were divided into different genotypes and the same integron was found in different genotypes. Conclusion: The integron is widespread in urinary tract infection of Escherichia coli. Integron is an important molecular mechanism mediating bacterial resistance. Genotyping results suggest that the integron is horizontally transmitted within the bacterial species.