食品中大肠埃希菌整合子与耐药性的关系研究

目的：研究食品中大肠埃希菌的整合子携带情况及其与耐药性之间的关系。方法：PCR检测细菌总DNA中1、2、3类整合酶基因，确定细菌携带整合子的情况。阳性菌株进一步检测整合子的可变区，分析插入基因盒的序列。结果：50株大肠杆菌中19株携带1类整合子，2株携带2类整合子，集中分布在对4种以上抗生素耐药的菌株中。插入基因盒主要是dfr和aadA类基因盒，各种基因盒组合中最常见的是dfr17-aadA5。结论：细菌的多重耐药性与整合子携带高度一致，但是单个菌株的耐药谱与整合子的耐药基因盒缺乏对应关系。

Relationship between antibiotic resistance and integrons of Escherichia coli isolated from food

Objective:To investigate the relationship between antibiotic resistance of Escherichia coli strains isolated from food and the integrons they harbored. Methods:PCRs amplifying intI gene and the variable region between the conserved segments (CS-PCR) were performed for class 1, class 2, and class 3 integron. And the integron content of every isolate was characterized by RFLP analysis and sequencing. Results:19 of 50 isolates were identified as being positive for integrase 1 gene in the total DNA, of which 13 had detectable amplification products for CS-PCR. Two Escherichia coli isolates had the class 2 integron. All the in tegron-positive strains were resistant to more 4 antibiotics. Most of the gene cassettes integrated in the integrons conferred resistant against trimethoprim and streptomycin-spectinomycin, and the integrons with the dfr 17-aadA 5 gene cassettes combination were predominant. Strains with different antibiotic resistance profile or plasmid profile may have the same integron.Conclusion:There was a good correlation between Integron-carrying and the antibiotic resistance of Escherichia coli strains isolated from food, but the antibiotic profile of an individual strain did not consist with the genecassettes of the integron it harbored.