Analysis on drug resistance genes of ESBLs-producing Escherichia coli and mcr-1 positive strains from a community in Binzhou, Shandong

  Objective  To analyze the molecular epidemiological characteristics of extended-spectrum β-lactamases-producing Escherichia coli (ESBL-EC) and polymyxin resistance gene mcr-1 positive strains from the intestinal tract samples of urban community residents.

  Methods  In this study, drug susceptibility test, whole genome sequencing (WGS)s and single nucleotide polymorphisms (SNPs) analysis were performed for 16 ESBL-EC strains isolated from the stool samples of residents in an urban community of Binzhou, Shandong province. S1-PFGE and Southern hybridization were performed for ESBL-EC which were resistant to polymyxin to identify the locus of the drug resistance gene. In addition, the conjugation experiment was conducted to determine the gene transferability.

  Results  The detection rate of ESBL-EC from the intestinal tract samples of the community residents was 40.00%, and the multidrug-resistance rate was 75.00%. WGS showed that 16 strains of ESBL-EC carried multiple drug resistance genes and virulence genes. SNPs analysis showed that 16 strains of ESBL-EC were divided into 4 clusters. The drug resistance genes, mcr-1 and bla_CTX-M carried by mcr-1 positive ESBL-EC were all in the plasmids and could transfer horizontally with the plasmids.

  Conclusion  Polymyxin resistant ESBL-EC and its resistance genes could be detected in urban community residents. Gene mcr-1 has the possibility of horizontal transmission.