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

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 coli and the class 1 integron.Methods The antimicrobial 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 dfr17-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.