Purpose: The emergence of New Delhi metallo-beta-lactamase (NDM) carbapenemase-producing Escherichia coli  leaves few therapeutic options. Infections due to NDM-7 carbapenemase-producing E. coli  are infrequent. In this study, we report the whole-genome sequence of an NDM-7 carbapenemase-producing E. coli  belonging to sequence type (ST) 410 isolated from a patient with a urinary tract infection in China.
Patients and methods: The NDM-7 producing E. coli  strain EC25 was isolated from a urine sample of a male patient hospitalized in a tertiary hospital in Zhejiang Province of China. Susceptibility assay of antibiotics was performed according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). The whole genome of the strain was sequenced, and the bla _NDM-7-harboring plasmid was analyzed. The genomic characterization and molecular epidemiology of the strain were further elucidated.
Results: E. coli  EC25 was resistant to all antimicrobials tested, except tigecycline and colistin. The whole genome of E. coli  EC25 was composed of one chromosomal DNA and five plasmids. Four virulence factors and twenty-five antimicrobial resistance genes, including bla _NDM-7 were identified. Resistance genes were all located in an IncF-type plasmid (pEC25-1), except bla _NDM-7 which was located in an individual IncX3-type plasmid (pEC25_NDM-7). Twenty-one phylogenetically related strains were identified. The phylogenetically related E. coli  ST410 strains exist globally. The closest relative strain of EC25 was a strain isolated from Sichuan province of China in 2016, with a similar IncX3-type plasmid that encoded bla _NDM-5.
Conclusion: Our study reports the emergence of an E. coli  ST410 strain harboring bla _NDM-7 in China. This strain may evolve as a successful epidemic clone of NDM-producing E. coli  in China, and the bla _NDM gene is prone to mutate during its dissemination.
Keywords: Escherichia coli , bla _NDM-7, IncX3 type plasmid, carbapenem resistant, ST410