Characterization of a novel NDM-5-harboring plasmid from a carbapenem-resistant Escherichia coli isolate from China

A carbapenem-resistant Escherichia coli (sequence type 5415) strain was isolated from a male patient. S1-PFGE and Southern blotting showed that the blaNDM-5 gene was located on a novel 66-kb IncFII [F2:A-:B-] plasmid. Conjugation assays revealed that the blaNDM-5-bearing plasmid was self-transferrable. Genomic sequencing and comparative analysis suggested that plasmid p2947-NDM5 likely originated from a combination of an IncFII-type backbone and the blaNDM-5 flanking genetic elements. This study highlights the genetic complexity of an NDM-5 carbapenemase and the urgent need for continuous active monitoring. IMPORTANCECarbapenem resistance due to the NDM enzyme has become a serious clinical problem in medical care and public health. We here identified a blaNDM-5-positive E. coli strain ST5414. The blaNDM-5 gene was located on a novel self-transferrable IncFII type plasmid p2947-NDM5. Genomic sequencing and comparative analysis suggested that plasmid p2947-NDM5 likely originated from a combination of an IncFII-type backbone and the blaNDM-5 flanking genetic elements. The genetic context of NDM-5 is highly similar to that of animal origins, and we speculate that the blaNDM-harboring IncFII plasmid has a potential risk of being transmitted from animals to humans and should be paid more attention. Our findings highlight the threat of NDM-5 carbapenemase circulation and the urgency of stringent surveillance and control measures.