Characterization of a novel ndm-5-harboring plasmid from a carbapenem-resistant escherichia coli isolate from China

Abstract

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 blaNDM-5 gene was amplified and confirmed by sequencing. Antimicrobial susceptibility testing was determined by a Vitek 2 compact system. The blaNDM-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 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 sug-gested that plasmid p2947-NDM5 likely originated from a combination of an IncFII-type backbone and the blaNDM-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 blaNDM-5 carrying plasmids and the urgent need for continuous active monitoring.