ABSTRACT
Objective:
To explore the
drug resistance mechanism and
gene structure characteristics of a carbapenemase-producing novel incompatibility group
plasmid pNY2385-KPC from
Citrobacter freundii.
Methods:
A multi-
drug resistant
strain was obtained from
urine samples of
patients with
fever in the
emergency ward of Li Huili
Hospital, Ningbo Medical Center. Bacterial species was preliminary identified and finally confirmed by
16S rRNA gene amplification and the average
nucleotide identity alignment, respectively. The
minimum inhibitory concentrations of the
antimicrobial agents were determined by VITEK 2 Compact System. The complete
genome sequence was obtained by "third-generation" sequencing
methods, and then detailed annotation of
gene function and
comparative genomic analysis of
plasmid structure were carried out by BLASTP/BLASTN, RefSeq, ConservedDomains, ResFinder, Isfinder, etc.
Results:
The pNY2385-KPC carried by
citrobacter freundii NY2385 belonged a novel incompatibility group, and contained blaKPC-2 and conjugative transfer (type Ⅳ secretory system, T4SS)
genes, which could induce conjugative transfer. A total of 15
plasmids of the same type as pNY2385-KPC were retrieved by NCBI, which were from
Citrobacter freundii, and the
rest were from
Serratia marcescens,
Escherichia coli,
Enterobacter cloacae,
Klebsiella pneumoniae, Raoultella planticola and other
bacteria, and were broad-host-range
plasmids. The sequence comparative
analysis of all 6 of the novel
plasmid from
Citrobacter freundii showed that the structure of the novel
plasmid had certain conserved property, with Tn6296 variant structure
carrying blaKPC-2, and
plasmid pCF1807-3 had both repApNY2385-KPC and repAIncX8.
Conclusion:
The pNY2385-KPC type
plasmids in
Citrobacter freundii carried blaKPC-2 resistance
gene, which were divided into two subtypes repApNY2385-KPC single replicator and repApNY2385-KPC/repAIncX8 complex replicator,
belonging to broad-host-range
plasmids. And as a
mobile genetic element, the
plasmids promote the spread of blaKPC-2.