A族链球菌emm基因序列分型与生物膜相关性研究

发布时间：2018-02-08 09:31

本文关键词： A族乙型溶血性链球菌 emm基因型生物膜相关性　出处：《重庆医科大学》2011年硕士论文　论文类型：学位论文

【摘要】：研究背景:A族乙型溶血性链球菌(group A streptococcus pyogens,GAS)是链球菌中致病性较强的一种细菌,是上呼吸道感染的重要致病原,可以引起急性扁桃体炎、猩红热和脓疱疮,也可引起严重的侵袭性感染如败血症、坏死性筋膜炎和链球菌中毒休克综合征。由emm基因编码M蛋白是GAS的主要致病因子,M蛋白抗原变异是M分型的基础。到目前为止,根据M蛋白抗原特异性可将GAS分为100多个型别,不同的型别其致病性不同,部分菌株感染可引起严重并发症如风湿热/风湿性瓣膜性心脏病(RF/RnD)及急性肾小球肾炎等。生物膜( b i o f i l m formation, B F )是一种包裹于细胞外多聚物基质中不可逆的黏附于非生物或生物表面的微生物细胞菌落,是细菌、真菌在生长过程中为适应生存环境而形成的一种与浮游细胞相对应的生存方式。生物膜被认为是各种致病菌的毒力因子,能够帮助细菌逃避抗生素或机体免疫系统的作用,引起许多细菌性疾病,像心内膜炎、骨髓炎、龋齿、中耳炎、医疗器械相关感染、眼窝植入物感染、囊性纤维化病人的肺部感染等,造成机体持续性感染或免疫性疾病。目前,对生物膜研究最多的是表皮葡萄球菌、金黄色葡萄球菌和铜绿假单胞菌,变形链球菌、格氏链球菌等。近些年来,国外已经有大量的实验证实GAS可以形成生物膜,且不同的emm基因型所形成的生物膜存在差异性。但中国目前还没有相关文献报道。目的:了解重庆地区A组乙型溶血性链球菌生物膜生长情况,了解GAS emm基因分型与生物膜的相关性。方法:对我院2000～2009收集的20株A族乙型溶血性链球菌培养、进行聚合酶链反应(PCR)扩增并测序,对emm基因进行分型。培养GAS及变形链球菌UA159的生物膜,并测量生物膜的吸光率。结果: (一)A组溶血链球菌的emm分型: 20株GAS菌株的emm分型分别为emm12.0、emm1.0、emm22.0、emm6.5和emm12.43、emm63.0、emm3.1、emm80.0、emm12.4、emm75.0、emml2.21、emm6.0、emml02.2、emmst181 .5、emm st38 (二)生物膜情况所有的15个emm基因型与阳性对照组(变形链球菌ua159)均可产生生物膜(p0.005).但不同的型别所形成的生物膜存在差异性。其中emmst38和emm12.43生物膜的生成能力要强于阳性对照,Emm12.0和emm75.0生物膜最弱。结论: (1)所有的基因型均可形成生物膜; (2)不同的emm基因型的生物膜在不同的时间段生长情况不尽相同,存在差异性; (3)同一基因型的生物膜在不同的时间段的生长情况不同。
[Abstract]:Background: group B hemolytic streptococci group A streptococcus pyogensensus (GASA) is a highly pathogenic bacteria in streptococcus. It is an important pathogen of upper respiratory tract infection and can cause acute tonsillitis, scarlet fever and pustular ulcers. Severe invasive infections such as septicemia, necrotizing fasciitis and streptococcal toxic shock syndrome can also be caused. M protein encoded by emm gene is the main pathogenic factor of GAS. The variation of M protein antigen is the basis of M typing. According to the specificity of M protein antigen, GAS can be divided into more than 100 types. Different types of GAS have different pathogenicity. Some strains infection may cause serious complications such as rheumatic fever / rheumatic valvular heart disease (RFR / RnD) and acute glomerulonephritis. Biofilm (bio f I l m formation (B F)) is a kind of microbial cell colony which is encapsulated in extracellular polymer matrix and adheres to abiotic or biological surface irreversibly. A way of living corresponding to planktonic cells formed during the growth of fungi to adapt to the environment. Biofilms are thought to be virulent factors for various pathogens that can help bacteria escape antibiotics or the body's immune system. It causes many bacterial diseases, such as endocarditis, osteomyelitis, dental caries, otitis media, medical device related infection, orbital implants infection, pulmonary infection of patients with cystic fibrosis, etc., resulting in persistent infection or immune diseases. At present, Staphylococcus epidermidis, Staphylococcus aureus and Pseudomonas aeruginosa, Streptococcus mutans, Streptococcus gravis and so on are the most studied biofilms. The biofilms formed by different emm genotypes are different, but there are no related literatures in China. Aim: to investigate the biofilm growth of group A hemolytic streptococcus B in Chongqing and the correlation between GAS emm genotyping and biofilm. Methods: 20 strains of Group A B hemolytic streptococcus collected from our hospital were cultured and amplified by polymerase chain reaction (PCR) and sequenced. The emm gene was genotyped. The biofilm of GAS and Streptococcus mutans UA159 were cultured and the absorptivity of biofilm was measured. Results:. (emm typing of Streptococcus haemolyticus in Group A:. The emm genotypes of 20 strains of GAS were emm12.0emm1.0emm22.0emm6.5 and emm12.43emm63.0 emm80.0emm12.4emm12.4emm75.0Emml2.2emm6.0Emml02.2emmst181 .5EMM st38. (II) Biofilm situation. All 15 emm genotypes and the positive control group (Ua159) could produce biofilm p0.005, but the biofilms formed by different types of biofilms were different. The biofilm production ability of emmst38 and emm12.43 was stronger than that of positive control. Emm 12.0 and emm75.0 biofilm were the weakest. Conclusion:. 1) all genotypes can form biofilm; (2) the biofilm growth of different emm genotypes was different in different time periods. 3) the growth of biofilm of the same genotype was different in different time periods.
【学位授予单位】：重庆医科大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：R378.1

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