Characterization of a Novel NDM-5-Harboring Plasmid from a Carbapenem-Resistant Escherichia coli Isolate from China

BACKGROUND: A carbapenem-resistant Escherichia coli (sequence type 5415) strain was isolated from a male patient through routine surveillance in 2018 in Guangzhou, China. MATERIALS AND METHODS: Bacteria were isolated from a sputum culture and identified by using the Vitek 2 compact system. The bla(NDM-5) gene was amplified and confirmed by sequencing. Antimicrobial susceptibility testing was determined by a Vitek 2 compact system. The bla(NDM-5) gene was located by Southern blotting. Whole-genome sequencing was carried out using both Illumina MiSeq and Oxford Nanopore MinION. RESULTS: S1-PFGE and Southern blotting showed that the bla(NDM-5) gene was located on a novel 66-kb IncFII [F2:A-:B-] plasmid. Conjugation assays revealed that the bla(NDM-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 bla(NDM-5) flanking genetic elements. CONCLUSION: This is the first report of an ST5414 E. coli strain expressing an NDM-5 β-lactamase. This study highlights the genetic complexity of bla(NDM-5) carrying plasmids and the urgent need for continuous active monitoring.