Characterization of blaNDM-5-bearing IncHI2 plasmid from Escherichia fergusonii in China.

Abstract

Objectives: Carbapenems are considered to be the last resort to the serious infections caused by multidrug-resistant (MDR) Gram-negative bacteria. The emergence of carbapenem-resistant Enterobacteriaceae has posed serious threat to human health. However, carbapenem resistance is rarely reported in E. fergusonii. In this study, an NDM-5 producing E. fergusonii strain EFSXRJ10 was isolated from chicken in China.

Methods: The minimal inhibitory concentrations (MICs) were determined using broth microdilution-based antimicrobial susceptibility testing. The complete genome sequence of the NDM-positive isolate was obtained through Illumina NovaSeq and Oxford Nanopore GridION sequencing platforms, followed by hybrid assembly with Unicycler. In the plasmid conjugation assay, the sodium azide-resistant E. coli strain J53 was employed as the recipient.

Results: Strain EFSXRJ10 was resistant to ampicillin, amoxycillin-Clavulanic acid, gentamicin, spectinomycin, tetracycline, florfenicol, sulfafurazole, cefotaxime, ceftazidime, apramycin and meropenem. The bla_NDM-5 gene was located on the IncHI2 plasmid. This plasmid can be transferred by conjugation at a frequency of (4.78 ± 0.67) × 10^-5. The bla_NDM-5-carrying plasmid which harboring 14 antibiotic resistance genes belonged to IncHI2/ST3 type and exhibited high similarity to other bla_NDM-5-carrying IncHI2 plasmids deposited in GenBank. The genetic structure surrounding bla_NDM-5 was organized as "IS3000-ΔISAba125-IS5-ΔISAba125-bla_NDM-5-ble_MBL-trpF-dsbD-IS26-∆umuD-∆ISKox3-∆IS3000".

Conclusions: This is the first report on the characterization of bla_NDM-5-bearing IncHI2 plasmid in E. fergusonii. Surveillance and control measures should be implemented to arrest the transmission of bla_NDM-5 from food animals.