携带blaKPC-2基因的肺炎克雷伯菌ST789型引起医院感染暴发

Outbreak of nosocomial infections due to Klebsiella pneumoniae ST789 isolates harboring blaKPC-2 gene

目的探讨医院耐碳青霉烯类抗菌药物肺炎克雷伯菌和大肠埃希菌的分子流行病学,为医院感染的预防和控制提供指导。方法收集医院2013年2-4月分离的对厄他培南耐药11株肺炎克雷伯菌和4株大肠埃希菌;细菌的鉴定和药敏试验使用法国生物梅里埃公司VITEK-2Compact系统;菌株是否产碳青霉烯酶按改良Hodge试验操作,其携带的β-内酰胺类耐药基则通过多重PCR进行检测,并经测序确认基因型;通过多位点序列分型和脉冲场凝胶电泳试验技术对细菌的同源性进行分析。结果分离的11株耐碳青霉烯类肺炎克雷伯菌多位点序列分型,分别是ST789型7株、ST437株型2和ST258型1株;经测序确认,10株携带有blaKPC-2基因;脉冲场凝胶电泳显示,3种带型A、B和C,7株ST789型肺炎克雷伯菌的带型一致;4株耐碳青霉烯类大肠埃希菌中有2株携带blaKPC-2基因,多位点序列分型均是ST131型;每一株菌可携带不同数目的超广谱β-内酰胺(blaSHV、blaTEM-1和blaCTX)基因。结论医院内存在携带blaKPC-2基因肺炎克雷伯菌引起的医院感染暴发流行,要加强消毒隔离,防止进一步播散。

OBJECTIVE To investigate the molecular epidemiology of the clinical carbapenem-resistant Klebsiella pneumoniae and Escherichia colii isolates so as to provide guidance for prevention and control of nosocomial infections.METHODS Totally 4strains of ertapenem-resistant E.coli and 11 strains of ertapenem-resistant K.pneumoniae were isolated from the hospitals from Feb 2013 to Apr 2013,then the bacterial identification and the drug susceptibility testing were carried out by using VITEK-2Compact system of BioMérieux,France,the modified Hodge test was conduced to determine whether the strains produced carbapenemase,theβ-lactam resistance genes in the strains were detected with the use of multiple PCR,and the genotypes were confirmed through sequencing;the homology of the strains was analyzed by means of multilocus sequence typing and pulsed-field gel electrophoresis（PFGE）.RESULTS The multilocus sequence typing of the 11 strains of carbapenem-resistant K.pneumoniae showed that there were 7strains of ST789,2strains of ST437,and 1strain of ST258;the sequencing confirmed that 10 strains carried with blaKPC-2gene.The 10 strains of KPC-2-producing K.pneumoniae were categorized into 3PFGE types（A,B and C）,and 7strains of K.pneumoniae ST789 were the same type.2of 4carbapenemresistant E.coli isolates harbored the blaKPC-2gene,and the multilocus sequence typing showed both strains were ST131;each strain could carry with different numbers of extended-spectrumβ-lactams genes（blaSHV,blaTEM-1and blaCTX）.CONCLUSIONThe K.pneumoniae harboring the blaKPC-2gene may result in the outbreak of nosocomial infection,thus,it is necessary to strengthen the disinfection and isolation so as to further dissemination.