本文選題：致瀉性大腸桿菌 + 腸集聚性大腸桿菌�。� 參考：《中國疾病預防控制中心》2013年碩士論文

【摘要】：致瀉性大腸桿菌(Diarrheagenic Escherichia coli)引起的感染性腹瀉是發(fā)展中國家面臨的一個重要公共衛(wèi)生問題。腸集聚性大腸桿菌(enteroaggregative Escherichia coli, EAEC)是一類新發(fā)現(xiàn)的致瀉性大腸桿菌,其特征是對HEp-2細胞的“疊磚樣”集聚性粘附表型(aggregative 'stacked-brick' pattern)。EAEC于1987年首次報道,并從一名患有頑固性腹瀉的智利兒童體內(nèi)分離到。EAEC致病機制相對復雜,且不同菌株間的異質(zhì)性(多態(tài)性)非常大。EAEC目前已在世界各發(fā)達和發(fā)展中國家引起散發(fā)或暴發(fā)流行。 本研究對河南省睢縣腹瀉患者糞便標本進行了EAEC分離,并對分離自河南、北京、山西的腹瀉患者糞便的EAEC菌株進行了血清分型、HEp-2細胞粘附分析、毒力及粘附相關(guān)基因檢測分析以及PFGE及MLST分子分型分析。 血清型檢測發(fā)現(xiàn),本研究中的53株EAEC菌株分屬于11種O血清群,16種H型,共可確定24株菌株的12種O：H血清型,其中03：H2(6株,占11.32%)是主要的血清型,表明EAEC的血清型眾多,僅僅依靠血清型檢測已不再是EAEC的有效檢測手段。HEp-2細胞粘附試驗中,53株aggR陽性的菌株中,36株表現(xiàn)為集聚性粘附(aggregative adherence,AA)粘附,其余菌株為不粘附；79株aggR陰性、astA陽性的菌株中,9株表現(xiàn)為AA粘附,6株表現(xiàn)為局灶性粘附(localized adherence,LA)粘附,其余64株均表現(xiàn)為不粘附。AA粘附表型與aggR基因型并不存在絕對的對應關(guān)系,但aggR基因仍然是典型EAEC有效的檢測標識。除毒力基因cdt、ipaH及set2外,53株aggR陽性的菌株中存在28個檢測毒力基因中的25個,菌株中最多的同時存在14個毒力基因,其中aap及pCVD432存在于所有的菌株中,79株aggR陰性、astA陽性的菌株中,除aggA、aafA、agg3A、 hdaA、aggB、aggR、cdt、cnf、ipaH、set2及sfaD-sfaE外,共可檢測到17個毒力基因,菌株中最多的同時存在7個毒力基因。由此可見,EAEC是一類高度異質(zhì)性的大腸桿菌,不同菌株所攜帶的毒力基因種類差異較大,在所檢測的毒力基因中,沒有一種毒力基因為具有AA粘附表型的EAEC菌株所特有。 PFGE可將我國分離的51株EAEC菌株及EAEC國際參考菌株042及17-2分成48個不同的PFGE帶型,表明EAEC菌株呈現(xiàn)高度多態(tài)性。MLST分析表明,53株EAEC菌株分屬于20個不同的ST型別,其中包括兩個新的等位基因型,分別為adk127和fumC133和三個新的ST型,分別為ST3748、ST3749及ST3750。ST10為優(yōu)勢ST型別,占18.87%,加強對該序列群EAEC菌株的研究,具有重要意義。本研究中分離的EAEC菌株,與國際暴發(fā)菌株相比,親緣關(guān)系較遠,但不排除我國出現(xiàn)EAEC暴發(fā)疫情的可能。
[Abstract]:Infectious diarrhea caused by diarrhoeal Escherichia coli (Escherichia) is an important public health problem in developing countries. Enteroaggregative Escherichia coli, EAEC) is a kind of newly discovered cathartic Escherichia coli, characterized by the "stacked-brick 'pattern).EAEC" agglomerative adhesion phenotype of HEp-2 cells, which was first reported in 1987. The pathogenetic mechanism of .EAEC isolated from a Chilean child suffering from refractory diarrhea is relatively complex, and the heterogeneity (polymorphism) among different strains is very large. EAEC has caused sporadic or epidemic outbreaks in developed and developing countries all over the world. In this study, EAEC was isolated from fecal specimens of diarrhea patients in Suixian County, Henan Province, and EAEC strains isolated from diarrhea patients' feces from Henan, Beijing and Shanxi were analyzed for serotyping of HEp-2 cells. Virulence and adhesion related gene analysis and PFGE and MLST molecular typing analysis. The serotype analysis showed that 53 EAEC strains in this study belong to 11 O serogroup 16 H serotypes, and 12 O: h serotypes of 24 strains can be identified, among which 03:H2(6 strain (11.32g) is the main serotype, indicating that EAEC serotypes are numerous. Serotyping alone is no longer an effective method for the detection of EAEC. 36 of 53 aggR positive strains in HEp-2 cell adhesion test showed aggregate adhesion. Among the 79 strains with negative aggR A positive, 9 strains showed AA adhesion, 6 strains showed focal adhesion, and the other 64 strains showed non-adhesion. AA adhesion phenotype did not correlate with aggR genotypes. However, aggR gene is still an effective detection marker for typical EAEC. There were 25 out of 28 virulence genes detected in 53 strains of aggR positive except for the virulence gene cdttteripaH and set2, and 14 virulence genes were found at the same time in most of the strains. Aap and pCVD432 were found in 79 strains with negative aggR A positive in all strains. 17 virulence genes were detected except for aggAaafAagg3A, hdaAaggBaggBaggRaggRdtcdtcnfnfnfnfimipaHset2 and sfaD-sfaE, and 7 virulence genes were found at the same time among the most virulent genes in the strain. It can be seen that EEAEC is a class of highly heterogeneous Escherichia coli, and the types of virulence genes carried by different strains vary greatly. None of the virulence genes detected is unique to EAEC strains with AA adhesion phenotype. PFGE could divide 51 EAEC strains isolated from China and EAEC international reference strains 042 and 17-2 into 48 different PFGE bands, indicating that EAEC strains showed high polymorphism. MLST analysis showed that 53 EAEC strains belonged to 20 different St types. There were two new allelic genotypes, adk127 and fumC133, and three new St genotypes, ST3748, ST3749 and ST3750.ST10, respectively, which accounted for 18.870.It is of great significance to strengthen the research on the EAEC strains of this sequence group. The EAEC strains isolated in this study were more closely related to those of the international outbreak strains, but the possibility of EAEC outbreak in China was not ruled out.
【學位授予單位】：中國疾病預防控制中心
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：R725.7

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