血流感染金黄色葡萄球菌分子特征及毒力基因分析

Molecular characteristics and virulence genes in Staphylococcus aureus strains causing bloodstream infection

目的 了解新疆军区总医院血流感染金黄色葡萄球菌临床分离株的分子特征,检测毒力基因携带情况及其对临床常用抗菌药物的耐药性。方法 收集2012-2016年新疆军区总医院不同血流感染患者分离的53株金黄色葡萄球菌,应用聚合酶链式反应(Polymerase Chain Reaction,PCR)鉴定甲氧西林耐药性;应用SCCmec分型、spa分型、多位点序列分型(multilocus sequence typing,MLST)等分子分型方法对金黄色葡萄球菌进行分析,PCR检测pvl等21种毒力基因,分析不同克隆毒力基因携带情况,观察菌株对临床常用抗菌药物的耐药性。结果 53株金黄色葡萄球菌中30株为耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA),23株为甲氧西林敏感金黄色葡萄球菌(methicillin-susceptible Staphylococcus aureus,MSSA)。30株MRSA菌分为4种ST型和4种spa型,3种SCCmec型,优势流行克隆为MRSA-ST239-t030-SCCmecⅢ占90.0%(27/30)同时鉴定出3株社区获得性MRSA。23株MSSA鉴定出10种ST型、14种spa型,主要流行克隆为ST22-t309,检出4株动物源性的克隆ST398。所有菌株中均检测到hla及hld两种溶血素基因,ST239克隆均携带有sea,see,hla,hld以及hlg-2基因,少量菌株还携带有pvl,sed等基因。ST22克隆则携带有包括pvl,seg等8种毒力基因。MRSA菌株对常用抗菌药物呈现高度耐药,MSSA菌株对青霉素、红霉素的耐药率分别为91.3%和69.6%,对其他抗菌药物敏感。结论 引起新疆军区总医院血流感染主要MRSA克隆为MRSAST239-t030-SCCmecⅢ,对抗菌药物耐药程度较高;主要MSSA克隆为ST22-t309,携带较多毒力基因,具有高毒力。

OBJECTIVE To investigate the molecular characteristics of clinical Staphylococcus aureus strains isolated from patients with bloodstream infection in Xinjiang Military General Hospital,detect the virulence genes in the strains and analyze the drug resistance to the commonly used antibiotics.METHODS Totally 53strains of S.aureus were isolated from the patients with bloodstream infection who were treated in Xinjiang Military General Hospital from 2012to 2016,the drug resistance to methicillin was determined by using polymerase-chain-reaction (PCR),the S.aureus strains were analyzed by means of SCCmec typing,spatyping and multilocus sequence typing( MLST),21types of virulence genes such as pvl were detected with the use of PCR,the clonal virulence genes that were carried by the strains were analyzed,and the drug resistance of the strains to the commonly used antibiotics was observed.RESULTS Of the 53strains of S.aureus,30were methicillin-resistant S.aureus (MRSA), and 23were methicillin-susceptible S.aureus (MSSA).Totally 4types of ST,4types of spaand 3types of SCCmec were detected in the 30strains of MRSA,MRSA-ST239-t030-SCCmecⅢ was the predominant prevalent clone,accounting for 90.0%(27/30),meanwhile,3strains of community-acquired MRSA were detected.Totally 10types of ST and 14types of spa were detected in the 23strains of MSSA,ST22-t309was the prevalent clone, and the animal-derived clone ST398was detected om 4strains.All of strains were detected to carry with two types of hemolysin genes hla and hld,the ST239clone carried with the sea,see,hla,hld and hlg-2genes,and few strains carried with pvl and sedgenes.ST22clone strains carried with 8types of virulence genes,including pvl and seg.The MRSA strains were highly resistant to the commonly used antibiotics,the drug resistance rates of the MSSA strains to penicillin and erythromycin were 91.3%and 69.6%,respectively,and the strains were highly susceptible to other antibiotics.CONCLUSION The MRSA-ST239-t030-SCCmecⅢis dominant among the MRSA clones causing the bloodstream infection in Xinjiang Military General Hospital and is highly resistant to antibiotics. The ST22-t309is the predominant MSSA clone and carries with multiple virulence genes,which is highly virulent.