Division of Virology, Quantitative Veterinary Epidemiology and Risk Analysis Group, Animal Sciences Group, Central Veterinary Institute, Wageningen UR, Lelystad, The Netherlands.
J Appl Microbiol. 2010 May;108(5):1552-62. doi: 10.1111/j.1365-2672.2009.04575.x. Epub 2009 Oct 7.
To demonstrate that a thorough characterization and virulotyping of Escherichia coli strains isolated from sheep over time leads to new insights into ovine E. coli potentially becoming human pathogens through horizontal gene transfer.
One hundred and fifty E. coli isolates from two sheep, sampled over 3 weeks, were characterized by serotyping, virulotyping, genotyping using multiple locus variable number tandem repeats analysis (MLVA) and susceptibility to phage infection in vitro. The 35 MLVA profiles and the serotype and virulotypes of the strains were closely associated. Many MLVA profiles differed in one locus independent of serotypes. Escherichia coli isolates of the same serotype or virulotype had identical or very similar MLVA profiles. No transductants that incorporated the bacteriophages were found in vivo, but six E. coli isolates were susceptible to the phage infection in vitro. Changes in MLVA profiles were seen after acquisition of Stx phages in vitro only.
The sheep carried Stx phage susceptible E. coli that possessed virulence markers associated with human pathogenicity. Changes in bacterial genomes by phage transfer may complicate outbreak source investigations. Serotype has to be taken into account when evaluating strain relationships by MLVA.
Sheep carry E. coli that encode for virulence markers and belong to serogroups known to be human pathogens. In addition, a selection of isolates was found to be susceptible to horizontal transfer of Shiga toxin genes by means of bacteriophages in vitro, and the transfer resulted in a discernible change of the MLVA patterns of E. coli.
通过对从绵羊中分离的大肠杆菌菌株进行全面的特征描述和毒力分型，以深入了解通过水平基因转移，这些潜在的绵羊源大肠杆菌可能成为人类病原体。
对两只绵羊在 3 周内采集的 150 株大肠杆菌进行了血清型、毒力型、多位点可变数目串联重复分析（MLVA）基因型以及体外噬菌体感染敏感性的特征描述。35 个 MLVA 图谱以及菌株的血清型和毒力型密切相关。许多 MLVA 图谱在一个与血清型无关的位点上存在差异。同一血清型或毒力型的大肠杆菌分离株具有相同或非常相似的 MLVA 图谱。在体内未发现能整合噬菌体的转导子，但有 6 株大肠杆菌分离株对噬菌体感染具有体外敏感性。仅在体外获得 Stx 噬菌体后才观察到 MLVA 图谱的变化。
绵羊携带对 Stx 噬菌体敏感的大肠杆菌，这些细菌具有与人类致病性相关的毒力标记。噬菌体转移引起的细菌基因组变化可能会使暴发源调查复杂化。在通过 MLVA 评估菌株关系时，必须考虑血清型。
绵羊携带编码毒力标记的大肠杆菌，这些大肠杆菌属于已知的人类病原体血清群。此外，还发现一部分分离株对噬菌体介导的志贺毒素基因的水平转移具有体外易感性，并且这种转移导致了大肠杆菌 MLVA 模式的明显变化。
