Characteristic of class 1 integron-cassette among Shiga toxin-producing E. coli isolates in China / 吉林大学学报(医学版)

ABSTRACT

Objective To explore the distribution and characteristic of class 1 integrons among Shiga toxin-producing E.coli(STEC) in China,and to elucidate the type of cassettes.Methods Antibiotics susceptibility was tested by the disk diffusion method,class 1 integron was detected by PCR assay and PCR products were sequenced and analyzed in eight isolates.Results Four isolates were multiple-drug resistant whose antibiogram were ampicillin,tetracycline,erythromycin,sulfamethoxazole/trimethoprim and ciprofloxacin,but two isolates conferred resistance of streptomycin and spectinomycin simultaneously.Only the two isolates carried class 1 integrons ranging in 1 000 bp which located on the plasmid of 7 800 bp.The sequenced PCR product demonstrated that the 1 000 bp integron harbored aad A1 gene cassettes conferred the resistance of streptomycin and spectinomycin;and linked with sul 1 and qacE?1 gene conferred the resistance of sulfamethoxazole and quaternary disinfectants.Conclusion The class 1 integrons exists among STEC isolates in China and determines the resistant antibiotics.