Drug-resistance characteristics,molecular typing,and biological properties of carbapenem resistant Klebsiella pneumoniae
10.13602/j.cnki.jcls.2025.11.14
- VernacularTitle:耐碳青霉烯类肺炎克雷伯菌的耐药特征、分子分型及生物学特性分析
- Author:
Yan WU
1
;
Yiquan ZHANG
1
;
Renfei LU
1
Author Information
1. 南通市第三人民医院检验科,江苏南通 226006
- Publication Type:Journal Article
- Keywords:
carbapenem-resistant Klebsiella pneumoniae;
carbapenemase;
molecular type;
virulence gene;
outer membrane protein
- From:
Chinese Journal of Clinical Laboratory Science
2025;43(11):868-874
- CountryChina
- Language:Chinese
-
Abstract:
Objective To analyze the drug resistance characteristics,molecular typing,and biological properties of carbapenem-resist-ant Klebsiella pneumoniae(CRKP).Methods A retrospective analysis was conducted on 31 non-repetitive CRKP strains collected clinically from April 2019 to May 2021 at the Third People's Hospital of Nantong.The Vitek 2 Compact microbial analysis system was used for bacterial identification and in vitro drug susceptibility analysis.The broth dilution method was used to determine the minimum inhibitory concentration(MIC)of polymyxin B.The disk diffusion testing was performed to supplement the susceptibility of five com-monly used antibiotics:ertapenem,cefotaxime,cefoxitin,cefoperazone-sulbactam,and tigecycline.The carbapenemase-resistance phenotype of CRKP strains was initially determined by a combined assay of modified carbapenem inactivation method(mCIM)and ED-TA-carbapenem inactivation method(eCIM).Certain carbapenemase resistance genes(blaKPC,blaNDM,blaIMP,blaVIM,and blaOXA-48),AmpC enzyme genes(blaDHA,bla ACC,blaCIT,blaEBC,blaMOX,and blaFOX),extended-spectrum β-lactamases(ESBLs)genes(blaSHv,blaTEM,and blaCTX-M),and nine virulence genes were amplified by PCR and subsequently verified by sequencing.The stringing test was used to screen for hypermucoviscous phenotype strains.The growth curves in vitro and biofilm formation assays,and multilocus se-quence typing(MLST)were performed on 31 isolates.Outer-membrane proteins were extracted and separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE)to evaluate the expressions of OmpK35 and OmpK36.Results All the 31 isolates were resistant to ampicillin/sulbactam,ampicillin,aztreonam,cefazolin,ceftriaxone,cefotaxime,cefuroxime,ciprofloxacin,pip-eracillin,piperacillin/tazobactam,meropenem,and ertapenem with resistance rate of 100％.The resistance to polymyxin B was ob-served in 32.26％,whereas tigecycline retained 100％susceptibility.In terms of MLST,three sequence types(STs)were identified,with ST15 being the most prevalent,accounting for 61.29％(19/31)of the isolates.All strains produced serine carbapenemase,and only blaKPC-2 was detected among carbapenem resistance genes.The virulence genes fimH and entB were present in all strains(100％,31/31),while the detection rate of mrkD was 80.64％(25/31).Some strains carried virulence genes such as rmpA,rmpA2,and other virulence genes,whereas magA gene was not detected in any isolate.The carriage rates of rmpA2,iutA,and mrkD were higher in ST11 strains than in ST15 strains.The string test was positive in 38.71％of the strains.The growth test showed that there was no significant difference observed in the growth curves among all strains in vitro,and all were able to form biofilms with varying degrees.All ST11 strains exhibited OmpK36 protein alterations,while OmpK35 protein was intact in the 31 strains.Conclusion CRKP strains in this hospital showed high drug-resistance rate,and ST15 was the predominant sequence type.All the isolates carried blaKPC-2 and virulence genes.Enhanced molecular surveillance and strengthened prevention and control measures of CRKP infection are urgently needed.
