多重PCR对大肠杆菌的毒力基因分型与系统进化分类的研究

Multiplex PCR Assays for Escherichia coli Phylogenetic Assignments and Virulence Gene Ownership

摘要:

本文对不同来源大肠杆菌的毒力基因分布情况进行调查及系统进化分类，探讨大肠杆菌的系统进化分类与毒力基因携带的关联。本研究针对引起人类和动物肠道内或肠道外疾病的6种病原型大肠杆菌的47个毒力基因，采用多重PCR方法对38株大肠杆菌和4株志贺氏菌进行毒力基因的分布调查及系统进化分类。肠道致病大肠杆菌中携带其病原型标志毒力基因和多种肠外致病大肠杆菌的毒力基因；非致病性大肠杆菌也携带某些肠外致病大肠杆菌的毒力基因，但是两者都不含肠道致病大肠杆菌的毒力基因。对42株菌的系统进化分类结果表明，大多数肠外致病大肠菌株属于B2或D。肠道临床菌株中大部分被归为D（19.2%）、B1（50.0%）和A（30.8%），3株非致病性菌株DH5α,BL-21和XL-10属于A。大肠杆菌毒力基因的携带和系统进化之间有很显著的联系，肠道内与肠道外的感染与不同的毒力基因相关联。

Abstract:

The relationship between different phylogroups and virulence genes of E.coli from various origins were identified. Forty-seven virulence genes (VGs) markers found in six pathotypes of E. coli known to cause intestinal and extra-intestinal disease in humans or animals were investigated. Multiplex PCR assays were used to screen 42 strains including clinical and commensal isolates for these virulence genes and assign the strains to phylogenetic group. Results showed that IPEC isolates possessed typical IPEC genes and some ExPEC genes. The non-pathogenic strains also possessed ExPEC genes. None of the ExPEC or non-pathogenic isolates harbored VGs typical for IPEC. The phylogenetic grouping of 42 isolates showed that most of the ExPEC strains belong to group B2 or D. Most of the intestinal clinical isolates were confined to groups D (19.2%), B1 (50.0%) and A (30.8%), Three non-pathogenic strains, DH5α,BL-21 and XL-10, belonged to group A. This study indicated that the presence of virulence genes were closely related to phylogenetic groupings.