华东部分地区禽大肠杆菌病的分子流行病学调查

发布时间：2018-06-16 12:48

本文选题：禽致病性大肠杆菌 + 多位点序列分型　；参考：《南京农业大学》2015年硕士论文

【摘要】：大肠杆菌是一种在自然界中广泛存在的一种细菌,多数大肠杆菌不具有致病性,只有少数大肠杆菌对人和动物具有致病性,禽致病性大肠杆菌(AvianPathogenic Escherichia coli,APEC)即是其中的一种。APEC能够引起禽类多种疾病,并具有传染性,目前在全世界范围内广泛流行,对家禽养殖业有巨大危害。不同国家和地区的APEC流行具有其各自的特点。为研究APEC在我国部分地区的流行情况,在华东地区多个家禽养殖场分离大肠杆菌,对分离到的大肠杆菌进行分子生物学鉴定与分析,通过致病性试验,确定了 77株致病性较强的菌株,并对这些具有致病性的菌株进行分子流行病学分析,主要包括系统进化分群、多位点序列分型、毒力因子检测等,确定优势群体并比较分析了这些病原菌的特点。此外,进行了药物敏感性试验,为临床用药提供指导。1 APEC毒力因子与系统进化分群的调查毒力因子是细菌具有致病力的一个主要原因,本次流行病学调查针对已知的几种毒力系统,通过特异性PCR的方法共检测了 26个毒力因子。检出率较高的几种毒力因子有:黏附因子当中有fimC(检出率为94.8%)、mat(检出率为98.7%),抗血清存活因子当中有iss·(检出率为81.8%)、ompA(检出率为97.4%);检出率较低的基因有:papC(检出率为11.7%)、pic(检出率为10.4%)、vgrG(检出率为)、ibeA(检出率为 10.4%)、neuC(检出率为 18.2%),afa、hlyA、cnf1及sat基因检出率为0。在系统进化分群上,B2和D群对于人类及禽类具有相对较高的致病性,依据以往的资料B2和D群在APEC当中较为流行。本次流行病学调查中所鉴定的77株禽致病性大肠杆菌当中,B2群和D群占据了 51%,A群和B1群则占据49%的比例,无显著差异。此外,毒力因子的分布显示,B2群和D群检出率较A群和B1群略高,A、B1、D、B2群的毒力因子平均检出数目分别为9/26,7.3/26,12.6/26,13.4/26,B1群与A群、D、B2群毒力因子检出数差异显著,但A群与D群、B2群的毒力因子平均检出数目差异不显著。2 APEC的多位点序列分型和耐药性调查77株禽致病性大肠杆菌当中,检出率最高的是 ST117 型,占 15.6%(12/77),其次是 ST23 型,占 9.1%(7/77),占 6.5%(5/77)。国外ST95型的大肠杆菌较为流行,本调查则揭示了在华东地区较为流行的大肠杆菌是ST117型,表明ST117型大肠杆菌具有一定的毒力。检测了这77株临床分离株对于6种类型的9种药物的耐药性。结果显示,这些菌株对这9种药物的耐药率普遍较高,对β-内酰胺类的氨苄西林及磺胺类药物耐药率最高,分别是93.5%和81.8%,对氨基糖胺类药物阿米卡星耐药率最低,为23.4%。此外,ST117型APEC具有较强的耐药性,可能是由于流行菌株频繁接触抗生素。
[Abstract]:Escherichia coli is a kind of bacterium widely existing in nature. Most of Escherichia coli is not pathogenicity, only a few Escherichia coli has pathogenicity to human and animal. Avian Pathogenic Escherichia coli (Avian Pathogenic Escherichia coli) is one of them. APEC can cause many diseases in poultry and is infectious. APEC epidemic in different countries and regions has its own characteristics. In order to study the prevalence of APEC in some parts of China, E. coli was isolated from several poultry farms in East China. The isolated Escherichia coli was identified and analyzed by molecular biology, and the pathogenicity test was carried out. 77 strains with strong pathogenicity were identified and analyzed by molecular epidemiology, including phylogenetic grouping, multi-locus sequence typing, virulence factor detection, and so on. The dominant population was determined and the characteristics of these pathogens were compared and analyzed. In addition, drug sensitivity tests were carried out to provide guidance for clinical use of Apec virulence factor and phylogenetic cluster investigation. 1 virulence factor was one of the main reasons for the pathogenicity of bacteria. A total of 26 virulence factors were detected by specific PCR for several known virulence systems. Some of the virulence factors with higher detection rate are: FIMC (94.8%), iss (81.8%) of the antiserum survival factors (97.4%), and lower detection rate (11.7m) of the genes in the adhesion factor (94.8%). (the detection rate is 98.7%), and the detection rate of the antiserum survival factor is iss (the detection rate is 81.8%), and the detection rate is 97.4% (the detection rate is 11.775%). The positive rate was 10.4% (detection rate was 10.4%) and the detection rate was 10.4% (detection rate was 10.4%). The detectable rate was 18.2kafahlyAf1 and the detection rate of sat gene was 0. Group B _ 2 and group D have relatively high pathogenicity to human and poultry on phylogenetic cluster, and B _ 2 and D are more popular in APEC according to the previous data. Among the 77 strains of avian pathogenic Escherichia coli identified in this epidemiological survey, group B _ 2 and group D accounted for 49% of the total number of group A and B _ 1, but there was no significant difference. In addition, the distribution of virulence factors showed that the detection rate of virulence factors in group B _ 2 and group D was slightly higher than that in group A and B _ 1. The average number of virulence factors detected in group A was 9 / 267.3 / 2612.6 / 2613.4 / 26B _ 1 and the number of virulence factors in group A was significantly higher than that in group A and group B _ 2, respectively. But there was no significant difference in the average number of virulence factors detected between group A and group D, among 77 strains of avian pathogenic Escherichia coli, ST117 was the highest detectable rate, accounting for 15.610 / 77, followed by ST23. It's 9. 1 / 7 / 77, 6. 5 / 7 / 77. E. coli ST95 was more prevalent in foreign countries. This investigation revealed that the most popular Escherichia coli in East China is ST117, which indicates that ST117 has a certain virulence. The drug resistance of the 77 clinical isolates to 9 drugs of 6 types was tested. The results showed that the resistance rates of these strains to these nine drugs were generally high, the highest rates of resistance to ampicillin and sulfamide were 93.5% and 81.8%, respectively, and the resistance rate to amikacin was the lowest (23.4B). In addition, ST117 APEC has strong resistance to antibiotics, which may be due to frequent exposure to antibiotics.
【学位授予单位】：南京农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S855.12

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