Study on CMY-2 AmpC ?-lactamase mediated by plasmid in Escherichia coli / 中华检验医学杂志

ABSTRACT

Objective To study the AmpC beta-lactarnase and its genotype mediated by plasmid in Escherichia coli.Methods AmpC beta-lactamase was detected based on that AmpC beta-laetamase can be inhibited by 3-aminophenylboronic acid(APB).MIC was ehecked by agar dilution method.Conjugation test was used to check the transfer of ampC gene.Gene chip and PCR were used to detect ampC gene.The amplified ampC gene were sequenced and analyzed by EMBOSS software.The molecular epidemiology of clinical isolates was investigated by Enterbacterial repetitive intergenic consensus(ERIC)typing method.Results In 74 strains of Escherichia coli insusceptible to cefoxtin,AmpC beta-lactamase was positive in 33 strains.8 strains possessed AmpC beta-lactamase of CIT group by gene chip and 8 transconjugants were obtained by conjugation test.CMY type ampC gene could be further amplified by specific CMY gene primers from both 8 clinical isolates of E.coli and plasmids extracted from 8 transconjugants.CMY-2 type ampC gene was found by sequencing(accession number DQ823449).The most transconjugants displayed similar MIC value(intermediate or resistant).ERIC genotyping showed 6 out of 8 isolates with CMY-2 ampC gene derived from different resource.Conclusion CMY-2 AmpC beta- lactamase mediated by plasmid could be detected in E.coli isolates from patients in the General Hospital of People Liberation Army,Beijing.The plasmid carried ampC gene could mediate multi-drug resistance.