医院内流行社区型MRSA的分子生物学特点分析

Analysis of the biological characteristics of community-associated MRSA strains prevalent in a hospital

目的调查2007-2009年沈阳医院分离MRSA感染的临床类型,并解析MRSA克隆的分子生物学特点。方法记录分析125株MRSA感染者的临床数据;多重PCR法分型SCCmec基因岛;凝固酶试验测定菌株的凝固酶型;聚合酶链式反应（PCR）测定PVL、CNA、SEH、TSST1等毒素基因在菌株中的分布情况。结果在检测的125株MR-SA中,76.0%（95/125）起源于社区,20.8%（26/125）起源于医院。成年MRSA感染平均年龄39.7岁,以皮肤、粘膜感染最常见;儿童患者以上呼吸道感染患者多见。CNA阳性菌株占73.6%,全部分泌4型血浆凝固酶,并携带IVc型SCC-mec基因岛。结论 1株起源于社区,基因型为IVc SCCmec-coagulase4且携带CNA毒素基因的特定MRSA克隆在医院内蔓延。

Objective To investigate the clinical features of the methicillin-resistant Staphylococcus aureus strains isolated in a Shenyang hospital and analyze the characteristics of MRSA clones.Methods The clinical data for each patient from whom MRSA was isolated were first recorded.In total,125 MRSA strains were analyzed.The SCCmec type was determined by multiplex PCR,and a coagulase test was conducted to determine the coagulase isotype;toxin genes of TSST1,SEH,CNA,PVL,and BAC were detected by single PCR reactions.Results Among the MRSA strains investigated,76%（95 in 125） were identified as originating in the community,and 20.8%（26 in 125） were identified as having a hospital origin.The average age for these patients from whom MRSA were isolated was 39.7.Cutaneous and mucosal infection was the most prevalent type of infection in adult patients and upper respiratory tract infection was highly prevalent in pediatric patients.The ratio of MRSA strains carrying the CNA gene was high（up to 73.6%）,and all of the CNA-positive MRSA strains produced type 4 coagulase and carried type IVc SCCmec elements.Conclusion A community-associated MRSA clone with type IVc SCCmec-coagulase 4 and carrying CNA toxin was prevalent in the hospital environment.