健康人群携带沙门氏菌第一类整合子与基因组岛的鉴定及特性分析

发布时间：2018-11-17 09:33

【摘要】： 目前,细菌的耐药性已经是世界关注的问题。细菌感染的发生率及其病原菌的耐药率一直居高不下,对人类的健康造成了很大的威胁。整合子-耐药基因盒系统作为病原菌主要的耐药机制之一,近年来已成为研究人员关注的热点,本研究将分析健康人群携带的沙门氏菌中第一类整合子及沙门氏菌基因组岛(SGI1)在的分布及特性,分析其与细菌耐药性的关系。将按照临床实验室标准化委员会(CLSI)的规定,用纸片扩散法药敏试验检测58株健康人携带的沙门氏菌对15种抗生素的敏感性。将通过聚合酶链反应(PCR)检测Ⅰ类整合酶基因(intI1),阳性者扩增耐药基因盒,并对阳性扩增产物进行测序,所得序列应用Standard nucleotide nucleotic BLAST在NCBI (http://www.ncbi.nlm.nih.gov )上比对并进行序列分析。应用滤膜法质粒接合转移试验对第一类整合子进行定位分析,并检测其可移动性。应用Sau-PCR方法对菌株进行分子分型,所得条带用Quantity One软件进行分析,绘制树状图。同时对第一类整合子阳性菌株检测沙门氏菌基因组岛(SGI1),分别检测其左侧、右侧部分及其中间的部分基因,阳性扩增产物进行测序及序列比对,对SGI1染色体外环状形式及切除进行检测,通过接合转移及自然转化试验检测其可移动性。研究结果表明:1、从健康人分离出的沙门氏菌耐药性较低,第一类整合子检出率不高,可能是由于面临较小的抗生素压力。07年与05年相比,耐药性及第一类整合子的检出率均有增高趋势。相关从业人员接触抗生素的机会不多,因此很可能是食品中细菌携带的整合子通过食物链播散给人。其携带的耐药基因盒与耐药表型相符,且可转移至其他细菌,介导细菌耐药的水平传播。第一类整合子阳性和阴性菌株的基因型无直接关联。2、首次阐述了从健康人分离的沙门氏菌携带SGI1这一现象,且SGI1可通过自然转化方式转移到其他菌株,介导多重耐药的传播。总之,健康人群中分离的沙门氏菌携带有第一类整合子及SGI1,且可以进行转移,这些菌株不仅可长期在人体内生存,且可以不断向外界进行排菌,与耐药性的广泛传播密切相关,一旦条件适合还有可能引起耐药菌株的暴发流行,因此我们应从基因水平全面监测细菌耐药情况,研究可能的耐药机制,从而为制定相应预防策略提供理论依据。
[Abstract]:At present, bacterial resistance has been a concern in the world. The incidence of bacterial infection and the rate of drug resistance of pathogens have been high, which poses a great threat to human health. Integron-drug resistance gene box system, as one of the main drug resistance mechanisms of pathogens, has become a hot topic in recent years. In this study, the distribution and characteristics of type I integron and Salmonella genomic island (SGI1) in healthy population were analyzed, and the relationship between them and bacterial resistance was analyzed. The susceptibility of 58 Salmonella strains carried by healthy people to 15 kinds of antibiotics will be tested by disk diffusion test according to (CLSI) of Clinical Laboratory Standardization Committee. Class I integrase gene (intI1) was detected by polymerase chain reaction (PCR). The sequence was analyzed by Standard nucleotide nucleotic BLAST on NCBI (http://www.ncbi.nlm.nih.gov). The plasmids conjugation transfer test was used to localize and detect the mobility of the first class integron. Sau-PCR method was applied to the molecular typing of the strains. The bands were analyzed by Quantity One software and the dendrogram was drawn. At the same time, the first group of integron positive strains were tested for Salmonella Genome Island (SGI1), the left, right and middle genes were detected, and the positive amplification products were sequenced and sequenced. The exocyclic form and excision of SGI1 chromosomes were detected and its mobility was detected by conjugation transfer and natural transformation test. The results showed that: 1, the drug resistance of Salmonella isolated from healthy people was low, and the detection rate of the first integron was not high, which may be due to the low antibiotic pressure. The detection rate of drug resistance and integron increased. Practitioners are not exposed to antibiotics, so it is likely that the integron carried by bacteria in food is spread through the food chain. The drug resistance gene box is consistent with the phenotype of drug resistance and can be transferred to other bacteria to mediate the horizontal transmission of drug resistance of bacteria. There was no direct correlation between the genotype of positive and negative integron strains of the first type. 2. The phenomenon of SGI1 carrying by Salmonella isolated from healthy people was first expounded, and SGI1 could be transferred to other strains by natural transformation. To mediate the spread of multidrug resistance. In short, salmonella isolated from healthy people carries Class I integrons and SGI1, and can be transferred, which not only can survive in the human body for a long time, but also can constantly expel bacteria from the outside world. Is closely related to the widespread spread of drug resistance and, once conditions are appropriate, it is possible to cause outbreaks of drug-resistant strains. Therefore, we should comprehensively monitor bacterial drug resistance at the gene level and study the possible mechanisms of drug resistance. Thus provides the theoretical basis for the formulation of corresponding prevention strategies.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：R378

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