耐甲氧西林金黄色葡萄球菌SCCmec分型及同源性研究

SCCmec typing and homology of methicillin-resistant Staphylococcus aureus

目的对下呼吸道标本中分离的耐甲氧西林金黄色葡萄球菌(MRSA)耐药机制、同源性及分子生物学分型进行研究,从分子水平了解其耐药特点,为临床用药提供参考依据。方法于2012年7月-2013年4月住院患者送检的下呼吸道标本中分离出金黄色葡萄球菌66株,常规方法进行分离鉴定,根据2013年CLIS规定检测其耐药性;PCR技术检测mecA基因,对其进行SCCmec分子生物学分型及耐消毒剂基因(qacA/B)检测;利用RAPD技术对其进行同源性分析。结果凝胶电泳结果表明,耐甲氧西林金黄色葡萄球菌SCCmec分子分型全部为ccrAB3型,mecA、qacA/B基因的携带率100.0%,并且同源性分析有5个克隆型。结论临床分离的下呼吸道标本耐甲氧西林金黄色葡萄球菌全部为ccrAB3型,并对普通消毒剂有相当程度的抗性;分离到的耐甲氧西林金黄色葡萄球菌中同源性分型不同菌株耐药率与其基因型之间存在有一定的关系,且这些菌株均为多药耐药株。

OBJECTIVE To study the drug resistance mechanisms, homology, and molecular biological typing of methicillin-resistant Staphylococcus aureus （MRSA） isolated from lower respiratory tract specimens and understand the molecular characteristics of drug resistance so as to guide the clinical use of antibiotics. METHODS Totally 66 strains of S. aureus , which were isolated from the lower respiratory tract specimens from Jul 2012 to Apr 2013. were identified by conventional method, then the drug resistance was determined according to the guidance of eLlS 2013 edition, the mecA gene was detected by means of PCR, the molecular biological typing of SCCmec and detection of disinfectant-resistant genes were performed, and the homology of the strains was analyzed with RAPD. RESULTS The result of gel electrophoresis assay showed that the SCCmec molecular typing of all the strains was ccrAB3, the carrying rates of the mecA gene and qacA/ B gene were 100. 0 %, and the homological analysis suggested that there were five clone types. CONCLUSION The ccrAB3 type has been detected in all the MRSA strains isolated from the lower respiratory tract specimens, and the strains carrying the ccrAB3 are highly resistant to the common disinfectants. Among the isolated MRSA strains with different homological types, the drug resistance rate, is correlated with the genotype, and the strains are multidrug-resistant.