Emergence of Coexisting blaNDM and mcr-1 Genes in Escherichia coli Isolates from the Guts of Healthy Individuals

Investigating the plasmid and genomic characteristics of blaNDM/mcr-1-positive E. coli isolates from the gut of healthy individuals. This study performed drug susceptibility testing, whole genome sequencing (WGS), analysis of resistance genes, characterization of plasmids, and single nucleotide polymorphism (SNP) analysis on blaNDM/mcr-1-positive E. coli isolates collected from the gut of 628 healthy individuals. Antimicrobial susceptibility tests showed that all isolates were resistant to various antimicrobial agentsGenome sequencing results showed that all 7 isolates carried multiple resistant genes, and there was a direct correlation between resistance genotype and resistance phenotype. SNP analysis demonstrated that the seven isolates were distributed across five clades, with a minimum pairwise difference of 341 SNPs. Data analysis from hybrid Illumina and PacBio platform sequencing also clarified the genetic locations and environmental characteristics of blaNDM/mcr-1 in the seven isolates. Close surveillance is urgently needed to monitor the emergence and potential dissemination of blaNDM/mcr-1-positive E. coli isolates among healthy individuals in endemic areas.