摘要目的 分析上海三级甲等医院2004-2010年血流感染的金黄色葡萄球菌克隆分型特点以及随时间的变化趋势,检测不同克隆株耐药和毒力基因携带情况.方法 收集上海华山医院2004-2010年从不同患者血液样本中分离鉴定的金黄色葡萄球菌103株,通过苯唑西林MIC测定和SCCrnec基因分型等方法对MRSA进行检测;按照国际通用的多位点保守基因测序(MLST)以及葡萄球菌A蛋白序列分析(spa typing)方法进行克隆株的鉴定分析,采用PCR方法对103株细菌的耐药以及毒力基因携带情况进行分析.结果 103株金黄色葡萄球菌共检出MRSA66株(64.1%),其中SCCmecⅡ型35株,SCCmecⅢ型29株,SCCmecⅣ型2株,MSSA 37株(35.9%).66株MRSA的克隆分型以ST5(33株)和ST239(29株)为主,另外还包括2株ST59.1株ST641,1株ST6;其他克隆型均为MSSA.从2009年开始ST5和ST239克隆株在血流感染中的分离率明显下降(ST5从52.9%降至15.4%;ST239从61.1%降至15.4%),而其他类型以及新出现的MSSA克隆株分离率明显增加(如2009年ST7分离率为41.7%;2010年新出现ST188及ST15等),2010年血流感染的MSSA为84.6%.103株金黄色葡萄球菌mupA耐药基因阳性19株(18.4%),qacA/B耐药基因阳性41株(39.8%),70.6%的ST239杀菌剂耐药基因qacA/B阳性.在这103株血流感染的金黄色葡萄球菌中发现5株动物来源的克隆株,分别为4株ST398以及1株ST9.22个毒力基因除了sasX、lukSF以及arcA外,同一克隆株无论MRSA还是MSSA其毒力基因携带情况无明显差异,但是不同克隆株携带毒力基因有明显的差异.结论 以ST5和ST239为主的MRSA在血流感染中的分离率明显下降,新的MSSA克隆株分离率明显增加,不同的克隆株耐药以及毒力基因的携带情况存在明显差别.

abstractsObjective To investigate the clonal types of Staphylococcus aureus collected from 2004to 2010 in patients with blood stream infection from a Grade A tertiary care hospital in Shanghai as well as the dynamic changes and to detect the variation in antimicrobial resistance and virulence-gene content in different strain types.Methods A total of 103 nonduplicate S.aureus isolates were collected from 2004 to 2010 from inpatients with S.aureus blood stream infection from Shanghai Huashan hospital.Determination of oxacillin MICs and the type of SCCmec gene were used to screen MRSA.Typing of S.aureus isolates was identified by using multilocus sequence typing(MLST) and S.aureus-specific staphylococcal protein A typing(spa typing),PCR was used to detect the antimicrobial resistance and virulence-gene.Results Sixtysix isolates(64.1%) MRSA were detected in 103 nonduplicate S.aureus isolates,and 35 isolates were MRSA with SCCmec type Ⅱ ,Twenty-nine isolates were MRSA with SCCmec type Ⅱ,two isolates were MRSA with SCCmec type Ⅳ,Thirty-seven isolates(35.9%) were MSSA.Thirty-three MRSA isolates were ST5,Twenty-nine MRSA isolates were ST239,two MRSA isolates were ST59,one MRSA isolates was ST641 and one MRSA isolates was ST6.All of the other clones belonged to MSSA.The percentage of ST5 and ST239 were decreased significantly after 2009(ST5 was decreased from 52.9% to 15.4%; ST239 was decreased from 61.1% to 15.4%),and new clonal types MSSA increased significantly(in 2009,the percentage of ST7 was 41.7%; new clonal types such as ST188 and ST15 were detected in 2010).In 2010,it was shown that 84.6% of MSSA were isolated from S.aureus blood stream infection,nineteen isolates(18.4%) harbored mupA gene and 41 isolates(39.8%) harbored qacA/B gene in 103 nonduplicate S.aureus isolates.It was shown that 70.6% ST239 harbored qacA/B gene.Four isolates of ST398 and 1 isolates of ST9were detected which were originally from animal.There was no significant difference of the virulence gene presence in the same strain types except sasX、lukSF and arcA genes,but there were a lot of genes which were restricted to different genomic background.Conclusions The percentage of ST5 and ST239 were decreased and new clonal types of MSSA were increased significantly in S.aureus blood stream infection,antimicrobial resistance and virulence-gene were restricted to different clonal types.