Epidemiological study on carriage of polymyxin-resistant gene mcr-1 in Enterobacteriaceae isolates
Objective To investigate the carriage of polymyxin-resistant gene mobile colistin resistance(mcr-1)in clinical isolates of Enterobacteriaceae.Methods From January 2018 to March 2022,1 400 non-duplicate Escherichia coli and 580 Klebsiella pneumonia clinical isolates were collected from Taizhou Hospital of Zhejiang Province.The mcr-1 gene in the Enterobacteriaceae isolates was detected by PCR.The minimum inhibitory concentration of antibiotics was determined by micro broth dilution and E-test in positive strains.The conjugation test was conducted to determine if the mcr-1 gene was on transferable plasmids.The bacterial DNA was sequenced by whole genome sequencing,analyzed for multilocus sequence typing and plasmid Inc typing,the resistance genes were identified.Results Among the 1 400 strains of Escherichia coli,6 were found carrying mcr-1,with a positive rate of 0.43％.Only 1 out of 580 Klebsiella pneumonia strains tested positive,with a positive rate of 0.17％.One Escherichia coli strain demonstrated resistance to carbapenem antibiotics.Five of the six mcr-1 positive strains were successfully transferred by conjugation.MLST typing revealed that the 6 mcr-1 positive Escherichia coli strains belonged to different ST types,including ST648,ST95,ST359,ST602,ST453,and ST156,while for Klebsiella pneumonia strain it was ST25.Different strains were found to have the same type of plasmids,indicating the possibility of horizontal transfer of these plasmids amongst strains.Resistance gene analysis revealed that seven strains carried many resistance genes,with one Escherichia coli and one Klebsiella pneumonia strain possessing both mcr-1 and carbapenem-resistance genes.Conclusion The prevalence of mcr-1 in Escherichia coli and Klebsiella pneumoniae strains exhibits a relatively low isolation rate.Nevertheless,given the potential for horizontal transmission of plasmids containing mcr-1 across diverse bacterial species,as well as the ability of mcr-1 to integrate with multiple resistance genes within the same plasmid,it becomes imperative to enhance the management of multidrug-resistant bacteria in clinical settings.
万方数据
维普
