耐甲氧西林金黄色葡萄球菌基因分型与同源性分析

Genotypes and homologous characteristics of methicillin-resistant Staphylococcus aureus

目的研究襄阳地区耐甲氧西林金黄色葡萄球菌(MRSA)的检出率及金黄色葡萄球菌染色体mec(SCCmec)基因型与同源性特征。方法采用苯唑西林/头孢西丁筛选法、mecA基因单一PCR扩增对2013年4-10月间湖北省襄阳地区4所三级医院门诊及住院患者标本分离的金黄色葡萄球菌进行MRSA筛选和确认;用多重PCR扩增(m-PCR)及脉冲场凝胶电泳(PFGE)进行SCCmec基因分型及同源性分析,并用单一PCR扩增法进行PVL基因的检测。结果从80株金黄色葡萄球菌菌株中分离出MRSA 43株;多重PCR分型结果显示,39株为SCCmecⅢ型,4株为SCCmecⅣa型;单一PCR法获得8株PVL阳性菌株,占18.6%,其中SCCmecⅢ型4株,SCCmecⅣa型4株;PFGE检测结果显示,43株MRSA中有A、B、C、D、E 5种类型,其中以A型为主,A型中又分为A1、A2、A3 3种亚型。结论襄阳地区MRSA以SCCmecⅢ型和A型克隆株为主,PVL基因的携带率较高,应加强感染控制,防止此类菌株的播散。

OBJECTIVE To explore the isolation rate of methicillin-resistant Staphylococcus aureus（MRSA）in Xiangyang area and study the genotypes and homologous characteristics of S.aureus chromosomal cassette mec（SCCmec）.METHODS By means of oxacillin/cefoxitin screening and mecA gene PCR amplification,the MRSA strains were screened and identified from the S.aureus strains that were isolated from specimens obtained from outpatients and inpatients of 4three-A hospitals from Apr 2013 to Oct 2013,then the genotyping of the SCCmec gene was carried out by using multiple PCR amplification（m-PCR）,the homology was analyzed by pulsed-field gel electrophoresis（PFGE）,and the PVL gene was detected with the use of single PCR amplification method.RESULTS Totally 43 strains of MRSA were isolated from 80 strains of S.aureus;the multiple PCR genotyping indicated that there were 39 strains of genotype SCCmec Ⅲ and 4strains of genotype SCCmec Ⅳa.Totally 8PVLpositive strains were acquired through the single PCR method,accounting for 18.6%,including 4strains of genotype SCCmec Ⅲ and 4strains of genotype SCCmecⅣa.The result of the PFGE showed that among the 43 strains of MRSA,there were 5genotypes（A,B,C,D,E）,and the genotype A was dominant and divided into 3subtypes（A1,A2,A3）.CONCLUSIONThe genotype SCCmec Ⅲ and type A clone strains are dominant among the MRSA strains in Xiangyang area,and the carrier rate of the PVL gene is high.It is necessary to strengthen the control of infections and prevent the spread of such strains.