摘要

大肠杆菌的系统发育与菌株的生活方式有关，共鉴定出7个系统群（A、B1、B2、C、D、E和F）。随着全基因组序列数据的积累，一些菌株属于F和B2系统群中间的一个类群，称为G系统群，本文研究了代表G系统群多样性的112个菌株的完整序列，发现它由一个主要的序列型复合体（STC）组成。）117和其他四个STC（STC657、STC454、STC738和STC174）。STC117的系统发育特点是内部分支很短，表现出广泛的O型多样性，但H型和FIMH等位基因的多样性很小，而其他STC则表现为主要的O、H和FIMH型。STC117菌株具有许多与肠外毒力相关的特性，在小鼠败血症模型中具有毒力，并表现出多药耐药性，如CTX-M产生。4524株澳大利亚和法国菌株的流行病学数据表明，STC117是一种与家禽相关的谱系，也可在人类中建立并引起肠外疾病。我们提出了一种简单的鉴别方法，将有助于在流行病学研究中追踪这种潜在的毒性和耐药性系统群。

The phylogeny of the Escherichia coli species, with the identification of seven phylogroups (A, B1, B2, C, D, E and F), is linked to the lifestyle of the strains. With the accumulation of whole genome sequence data, it became clear that some strains belong to a group intermediate between the F and B2 phylogroups, designated as phylogroup G. Here, we studied the complete sequences of 112 strains representative of the G phylogroup diversity and showed that it is composed of one main sequence type complex (STc)117 and four other STcs (STc657, STc454, STc738 and STc174). STc117, which phylogeny is characterised by very short internal branches, exhibits extensive O diversity, but little H-type and fimH allele diversity while the other STcs are characterised by a main O, H and fimH type. STc117 strains possess many traits associated with extra-intestinal virulence, are virulent in a mouse sepsis model and exhibit multi-drug resistance such as CTX-M production. Epidemiologic data on 4524 Australian and French strains suggest that STc117 is a poultry associated lineage that can also establish in humans and cause extra-intestinal diseases. We propose an easy identification method that will help to trace this potentially virulent and resistant phylogroup in epidemiologic studies. This article is protected by copyright. All rights reserved.

https://www.ncbi.nlm.nih.gov/pubmed/31188527