Molecular epidemiological characteristics of carbapenem-resistant Raoultella ornithinolytica
Objective To understand the clinical prevalence and drug resistance of Raoultella ornithinolytica,and to analyze the drug-resistant characteristics of carbapenem-resistant strains.Methods A total of 83 clinical isolates of R.ornithinolytica,identified using matrix-assisted laser desorption ionization time-of-flight mass spectrometry between May 2015 and December 2020,were collected.Clinical information,drug-resistant phenotype,and carbapenemase gene of the carbapenem resistant strains were analyzed.Homology of the resistant strains was examined by pulse-field gel electrophoresis(PFGE).The molecular characteristics of plasmids,drug resistance genes and virulence genes were determined by whole genome sequencing(WGS),and a phylogenetic tree was constructed based on core single-nucleotide polymorphisms(core-SNPs)for evolutionary analysis of the carbapenem-resistant strains.Results All 83 clinical isolates were confirmed as R.ornithinolytica,of which 11strains were resistant to carbapenem antibiotics.The resistant strains were mainly sourced from the drainage fluid and wound secretions of patients in surgery,intensive care unit and oncology department.In addition to carbapenems resistances,the 11 strains were also resistant to cephalosporins,cephamycins,and aztreonam,while maintaining good in vitro activity to levofloxacin,tigecycline and colistin.Carbapenemase gene detection showed that 8 strains carried the blaIMP-4,3 carried blaKPC-2,of which 1 strain carried both blaIMP-4 and blaKPC-2,and 2 strains carried both blaIMP-4and blaNDM-1.PFGE results showed 7 banding types and 4 epidemic strains.WGS identified plasmid replicon types carried by the 1istrains of R.ornithinolyticus including IncFIA,IncFIB,IncHI1B,IncU,repB and Col,along with 10 additional types of drug resistance genes.Iron carrier related virulence genes entB,fyu,ybt and irp were detected in all carbapenem-resistant strains.Phylogenetic analysis showed that Ro6348 and Ro6050,Ro7401 and Ro7242,Ro8647 and Ro5832,and Ro9907 and Ro8856 were grouped together,while Ro8454,Ro7349 and Ro7326 were located on different branches.Conclusions The overall drug resistance of R.ornithinolytica closely resembles Klebsiella pneumoniae and carries a variety of drug-resistant genes,but differs from domestic K.pneumoniae in that its carbapenemase is mainly IMP-4.PFGE and phylogenetic analysis results suggest that the strain has a tendency of mutual transmission in hospital,which deserves more attention.
万方数据
维普
