Analysis of genetic homology and genotyping in Carbapenems-resistant Klebsiella pneumonia

Abstract

Objective To investigate genotyping and homology of Carbapenems-resistant Klebsiella pneumonia isolated from clinical specimens. Methods A total of 175 clinical isolates of Carbapenems-resistant Klebsiella pneumoniae were isolated from clinical specimens from January 2011 to June 2012.Antimicrobial susceptibility testing was performed by MIC method according to guidelines of CLSI.Extended-spectrum β-lactamases (ESBLs) were detected by phenotypic confirmatory test.The carbapenemase were confirmed by modified Hodge test (MHT). β-lactamases genes were amplified by polymerase chain reaction (PCR),the PCR products were subjected direct sequencing of both directions,BLAST were preformed to confirm the genotypes of β-lactamases.DNA fingerprinting based on repetitive-sequence-based PCR (REP-PCR) to investigate the homology of Carbapenems-resistant Klebsiella pneumonia. Results Of 175 clinical isolates of carbapenems-resistant Klebsiella pneumonia,80.0% (140/175) strains appeared positive response of MHT.PCR and sequencing analyses showed that 58.3% (102/175) strains harbored blaKPC-2genes,3.4% (6/175) harbored blaIMP-4genes.There was 11.4% (20/175) strains which harbored blaDHA-1genes,and 28.6% (50/175) strains which produced ESBLs by phenotypic test.There was 89.1% (156/175) strains which harbored blaSHVgenes,and 63.4% (111/175) strains harbored bla TEMgenes.There was 50.3% (88/175) strains which harbored blaCTX-Mgenes.More than three kinds of resistant genes were detected simultaneously in 66.9% (117/175) strains.DNA fingerprinting showed that 3 to 8 discernible DNA bands ranging in size from 200 bp to 1600 bp were generated by REP-PCR amplification.According to the results,the 175 strains were categorized into 12 types of gene pattern,in which 71 (40.6%) strains were pattern G,followed by 35 (20.0%) strains were pattern F. Conclusions The major genotype causing Carbapenems resistance in Klebsiella pneumoniae is blaKPC-2,followed by blaIMP-4. The major genotype of ESBLs is blaCTX-M-14. There is an Epidemic of clone strains in some hospitals in China.There are genetic difference between the epidemic strains in different area,the epidemic strains is majorly pattern Gin the A hospital in Beijing,while pattern F in Hangzhou.(Chin J Lab Med,2013,36:318-323) Key words: Klebsiella pneumoniae; Carbapenems; Drug resistance; bacterial; Genotype; beta-Lactamases