【作者】 严平；

【导师】 张钧；

【作者基本信息】 浙江大学 ， 临床检验诊断学， 2015， 硕士

【摘要】 背景及意义甲氧西林耐药的金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)是指对苯唑西林、甲氧西林、和氟氯西林等异唑青霉素耐药的金黄色葡菌球菌菌株,于1961年由Jevons首次发现,是引起医院感染的重要病原菌之一。其传播速度快,适应性强,从发现至今,感染几乎遍及全球。具有多重耐药性和潜在的致死性等特点,存在局部暴发流行的潜在威胁。我国自20世纪70年代发现第1株MRSA后,其分离率在中国迅速上升。目前MRSA已成为医院和社区人群感染的常见病原菌,不但致病能力强,耐药谱广,而且对多种抗菌药物的敏感性呈现逐年降低趋势,已经成为严重危害公众健康的感染性因子之一,使临床抗感染治疗面临极大困难,由此也成为医学界关注的焦点问题。该菌对目前临床上使用的大多数抗菌药物有很高的耐药率,并可对β内酰胺类、氨基糖苷类、喹诺酮类、大环内酯类等常用抗菌药物产生多重耐药。临床可供选择的抗生素较少,是目前抗感染治疗的难点。当前基因分型的分子流行病学研究方法在揭示病原菌的进化及遗传特性,确定某一感染暴发流行的致病菌株克隆或相关基因来源,追踪基因水平的转移与播散,调查院内耐药性质粒在不同细菌间播散等方面发挥重要作用。但截至目前国内对MRSA系统全面的基因分型及分子学特性方面的研究较少,或片面不完整。本课题采用三种基因分型技术：多位点序列分型(MLST)、葡萄球菌染色体mec基因盒(SCCmec)和葡萄球菌蛋白A基因(spa),同时应用脉冲场凝胶电泳(PFGE)对收集的菌株进行同源性分析,PCR扩增技术筛查菌株的pvl毒素基因,力求全面揭示我市MRSA流行株的具体基因型别及分子学特性。研究临床分离MRSA的流行、药物敏感性情况,有助于我们掌握本地区MRSA的流行特点及趋势,为制定控制其传播措施以及临床经验性治疗提供理论依据；开展对临床分离MRSA的基因分型研究,了解本地区或某家医院MRSA流行株的遗传和基因分型特征,分析判断流行菌株间的亲缘关系,全面揭示MRSA流行株的基因型变化趋势,药敏及流行病学特点,有助于医院或疾控部门采取有效措施控制感染的暴发流行,对于遏制流行菌株的进一步播散和积极控制MRSA的感染以及指导临床治疗、合理应用抗生素有着十分重要的意义。同时,开展对MRSA的相关研究,有利于提高基层临床医师对MRSA的知晓率,引起广大医务人员对其引起医院感染的高度重视,严格执行消毒隔离措施,积极治疗并隔离MRSA患者及携带者,严格控制广谱抗生素的应用。目的研究杭州富阳区临床分离的甲氧西林耐药金黄色葡萄球菌(MRSA)的检出率、药敏情况及基因分型、同源性分析等分子学特性,分析富阳区MRSA的流行现状。方法收集2013年11月至2014年10月两家医院从各种类型临床标本中分离出的金葡菌,对其中经筛选确认的44株MRSA进行MLST、spa、SCCmec基因分型,筛查pvl基因,应用PFGE进行菌株间的同源性分析。同时应用Vitek2 compact药敏分析系统对16种抗菌药物进行药敏实验。结果共检出MRSA44株,占金葡菌的16.4%(44/268)。两家医院流行的主要克隆不同,富阳中医骨伤医院以ST59-t437-SCCmecIV型为主,菌株间同源性程度低；人民医院以ST5-t311-SCCmecⅡ型为主,部分菌株之间同源性程度高。检出3株pvl阳性菌株,占6.8%。药敏结果示MRSA对β内酰胺类普遍耐药,红霉素、克林霉素的耐药率高,对万古霉素、利奈唑烷、替加环素保持敏感。结论富阳地区MRSA的检出率相对较低,整体呈低流行、散发态势。两家医院MRSA流行的主要克隆有较大差异。MRSA的耐药情况不容乐观,多重耐药的现象严重。不同基因型别的菌株其药敏结果有差异。更多还原

【Abstract】 Background and significanceIn recent years, methicillin-resistant Staphylococcus aureus (MRSA) become a truly global challenge. It is a major human pathogen that causes a broad range of serious community-acquired and nosocomial diseases in humans,from minor skin infections to severe infections such as septicemia, septic shock, severe pneumonia, and et al.. In china it was first introduced in 1970s, then the separation rate increased rapidly. At present, MRSA has become a common pathogenic bacteria in hospital and community. It is not only with strong pathogenic ability and widely drug resistance spectrum, but also with a decreased trend year by year of sensitivity to variety of antimicrobial agents. As the result of one of the most serious infectious factors of public health. MRSA makes great difficulties for doctors to treat the patients who are infected by it. The MRSA has a high resistance rate to most of the antibiotics used in clinic currently and is multidrug-resistant β-lactam antibiotics, aminoglycosides, quinolones, macrolides etc. there are few antibiotics could choosed in clinic now.The increasing prevalence of MRSA and its ability to spread in hospitals and communities,has posed a major challenge for infection control. Knowledge of epidemic and the drug-sensitivity characteristics of MRSA clones can help the development of effective strategies to aid in controlling dissemination, optimizing treatment, and revealing the mode of pathogenicity. Monitoring the prevalent MRSA clones through current genotyping techniques is a crucial step to reveal relatedness among isolates.In FuYang, there is limited detailed data on Staphylococcus aureus especially the MRSA obtained from both inpatient and outpatient populations, and little attention has been paid to the molecular epidemiology of this pathogen. Accordingly,this study was conducted to better understand MRSA infections and to characterize the isolates by a variety of molecular typing techniques, eventially provide an overview of the MRSA. It will be great help for medical staff and the department of Hospital Infection Management to be more familiar with the epidemiology and drug susceptibility characteristics of MRSA, also be helpful to the workers in the Centers for Disease Control (CDC) to grasp the molecular characteristics of MRSA strains in our local area.ObjectTo investigate the genotype,epidemic characteristics and resistance of MRSA in Fuyang area.MethodStaphy-lococcus aureus were collected from kinds of specimens in two hospital in Fuyang area between November 2013 and October 2014. pvl assay, MLST, spa, SCCmec typing and PFGE typing were carried out with all the MRSA isolates. Drug-sensitivity test was finished by the vitek2 compact automatic system.Results44 MRSA strains were involved in our study.which was 16.4% of the Staphylococcus aureus.Two involved hospitals hold different epidemic clones: ST59-t437-SCCmecIV in Orthopedics & Traumatology Hospital and ST5-t311-SCCmec Ⅱ in the other hospital.The homology of the strains collected from the people’s hospital was high.6.8% (3/44) isolates were positive for PVL. All MRSA isolates were resistant to the β-lactam antibiotics, more than 85.0% resistant to Erythromycin and Clindamycin and were completely susceptible to Vancomycin, Linezolid and Tigecycline.ConclusionNow the detectable rate of MRSA in Fuyang is low relatively, and generally speaking,the prevalence of MRSA in FuYang is sporadic. the drug resistance of MRSA is serious, and the phenomenon of multiple resistance is very common. the result of the drug-sensitive is associated with the gentype of the isoaltes.更多还原