Coexistence of two blaCTX-M-14 genes in a blaNDM-5-carrying multidrug-resistant Escherichia coli strain recovered from a bloodstream infection in China

Abstract

The emergence of carbapenem-resistant Enterobacteriaceae has become a serious public-health threat. Here we report the complete genome sequence of a multidrug-resistant (MDR) Escherichia coli carrying blaNDM-5 and two copies of blaCTX-M-14 recovered from a bloodstream infection in China. Whole-genome sequencing of E. coli strain 2D was performed both using Oxford Nanopore MinION and Illumina NovaSeq 6000 platforms. De novo hybrid assembly of short Illumina reads and long MinION reads was performed using Unicycler. In silico multilocus sequence typing (MLST), antimicrobial resistance genes and plasmid replicons were identified from the genome sequence. Core genome MLST (cgMLST) analysis between E. coli 2D and all ST354 E. coli strains retrieved from the NCBI GenBank database was performed using BacWGSTdb 2.0 server. The complete genome sequence of E. coli 2D consists of six contigs comprising 5 363 300 bp, including one chromosome and five plasmids, and was assigned to ST354. Six antimicrobial resistance genes were identified, including blaNDM-5 located in a 46 161-bp IncX3 plasmid and two copies of the blaCTX-M-14 gene located both in the chromosome and in a 96 499-bp IncB plasmid. The closest relative of E. coli 2D was another isolate recovered from Lebanon, which differed by 162 cgMLST loci. This study reports the first genome sequence of a MDR E. coli carrying blaNDM-5 and two copies of blaCTX-M-14 in China. These data may help to understand the antimicrobial resistance mechanisms and transmission dynamics of carbapenem-resistant Enterobacteriaceae in clinical settings.