本文選題：禽致病性大腸桿菌 + 多位點序列分型�。� 參考：《南京農(nóng)業(yè)大學》2015年碩士論文

【摘要】：大腸桿菌是一種在自然界中廣泛存在的一種細菌,多數(shù)大腸桿菌不具有致病性,只有少數(shù)大腸桿菌對人和動物具有致病性,禽致病性大腸桿菌(AvianPathogenic Escherichia coli,APEC)即是其中的一種。APEC能夠引起禽類多種疾病,并具有傳染性,目前在全世界范圍內(nèi)廣泛流行,對家禽養(yǎng)殖業(yè)有巨大危害。不同國家和地區(qū)的APEC流行具有其各自的特點。為研究APEC在我國部分地區(qū)的流行情況,在華東地區(qū)多個家禽養(yǎng)殖場分離大腸桿菌,對分離到的大腸桿菌進行分子生物學鑒定與分析,通過致病性試驗,確定了 77株致病性較強的菌株,并對這些具有致病性的菌株進行分子流行病學分析,主要包括系統(tǒng)進化分群、多位點序列分型、毒力因子檢測等,確定優(yōu)勢群體并比較分析了這些病原菌的特點。此外,進行了藥物敏感性試驗,為臨床用藥提供指導(dǎo)。1 APEC毒力因子與系統(tǒng)進化分群的調(diào)查毒力因子是細菌具有致病力的一個主要原因,本次流行病學調(diào)查針對已知的幾種毒力系統(tǒng),通過特異性PCR的方法共檢測了 26個毒力因子。檢出率較高的幾種毒力因子有:黏附因子當中有fimC(檢出率為94.8%)、mat(檢出率為98.7%),抗血清存活因子當中有iss·(檢出率為81.8%)、ompA(檢出率為97.4%);檢出率較低的基因有:papC(檢出率為11.7%)、pic(檢出率為10.4%)、vgrG(檢出率為)、ibeA(檢出率為 10.4%)、neuC(檢出率為 18.2%),afa、hlyA、cnf1及sat基因檢出率為0。在系統(tǒng)進化分群上,B2和D群對于人類及禽類具有相對較高的致病性,依據(jù)以往的資料B2和D群在APEC當中較為流行。本次流行病學調(diào)查中所鑒定的77株禽致病性大腸桿菌當中,B2群和D群占據(jù)了 51%,A群和B1群則占據(jù)49%的比例,無顯著差異。此外,毒力因子的分布顯示,B2群和D群檢出率較A群和B1群略高,A、B1、D、B2群的毒力因子平均檢出數(shù)目分別為9/26,7.3/26,12.6/26,13.4/26,B1群與A群、D、B2群毒力因子檢出數(shù)差異顯著,但A群與D群、B2群的毒力因子平均檢出數(shù)目差異不顯著。2 APEC的多位點序列分型和耐藥性調(diào)查77株禽致病性大腸桿菌當中,檢出率最高的是 ST117 型,占 15.6%(12/77),其次是 ST23 型,占 9.1%(7/77),占 6.5%(5/77)。國外ST95型的大腸桿菌較為流行,本調(diào)查則揭示了在華東地區(qū)較為流行的大腸桿菌是ST117型,表明ST117型大腸桿菌具有一定的毒力。檢測了這77株臨床分離株對于6種類型的9種藥物的耐藥性。結(jié)果顯示,這些菌株對這9種藥物的耐藥率普遍較高,對β-內(nèi)酰胺類的氨芐西林及磺胺類藥物耐藥率最高,分別是93.5%和81.8%,對氨基糖胺類藥物阿米卡星耐藥率最低,為23.4%。此外,ST117型APEC具有較強的耐藥性,可能是由于流行菌株頻繁接觸抗生素。
[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.
【學位授予單位】：南京農(nóng)業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：S855.12

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本文編號：2026755