不同遗传谱系肠外大肠埃希菌毒力因子检测

Detection of extraintestinal E. coli virulence factors based on different phylogenetlc groups

目的通过检测肠外致病性大肠埃希菌（ExPEC）30种毒力因子了解其基因的检出情况及遗传谱系分型情况，并初步探讨两者关系，探究ExPEC的分子流行病学特点。方法210株分离自血液、尿液及其他部位的菌株参与研究，采用多重PCR方法检测临床分离菌株毒力因子基因的存在情况并进行遗传谱系分型，比较菌株遗传谱系分型各组间毒力因子基因的检出情况是否有差异。结果ExPEC中毒力基因fimH,fyuA、traT、iutA、kpsMTⅡ、PAI，的检出率较高；遗传谱系分型表明4组百分比分别为24％、11％、29％和36％。在各组之间进行毒力因子基因检出情况比较显示，毒力因子中有8种仅与B2组联系密切，4种仅与D组联系密切，6种与B2组和D组均有关。结论ExPEC遗传潜系分型主要属于B2组和D组，ExPEC毒力因子基因检出情况与菌株遗传谱系分型关系密切。

Objective To investigate the molecular epidemiological characteristics of extraintesti- hal pathogenic E. coli（ExPEC） clinical isolates by firstly detecting their 30 known virulence factors and phy- Iogenetic groups A, BI, B2 and D, secondly analyzing the relationship between these virulence factors and phylogenetie groups. Methods A total of 210 ExPEC clinical isolates were investigated. Multiplex PCR was performed to detect the 30 virulence factors among the 133 E. coli strains isolates. For the virulence fac- tors statistical analysis, the comparisons of proportions between groups were evaluated by using Fisher＇s exact test. Results In this study we found that, the following virulence factor genesfimH, fyuA, traT, iutA, kpsMT Ⅱ and PAl have a higher detection rate 79%, 75%, 74%, 73%, 62% and 46% perspectively. For all isolates strains, 24%, 11%, 29% and 36% were assigned to the phylogroup A, B1, B2 and D, respec- tively, pagG alle Ⅱ, papA, sfa/focDE, hlyA, rfc, cnfl, cvaC and FocG were only associated with phylo- group 112. papG flanking Ⅱ and Ⅲ, afa/draBC, kpsMT Ⅲ and nfaE were only linked to phylogroup D. In contrast, fyuA , PAl, K 5 , papEF, K 1 and papC were associated with phylogroup B 2 and D. Conclusion The phylogenetic groups of ExPEC belong mainly to the group 132 and D. The virulence factors and phyloge- netic groups of extraintestinal pathogenic E. coil are closely related.