Cobbaut Katrijn, Houf Kurt, Buvens Glenn, Habib Ihab, De Zutter Lieven
Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
Vet Microbiol. 2009 Jul 2;138(1-2):174-8. doi: 10.1016/j.vetmic.2009.02.008. Epub 2009 Feb 20.
Escherichia coli O157 is often associated with hemorrhagic colitis and the hemolytic uremic syndrome (HUS). The verocytotoxins are considered to be the major virulence determinants. However, vt-negative E. coli O157 were recently isolated from patients with HUS. Several transmission routes to humans are described, but cattle feces are the primary source from which both the food supply and the environment become contaminated with E. coli O157. In a prevalence study performed on dairy, beef, mixed dairy/beef and veal farms in the summer of 2007, vt-negative isolates were detected on 11.8% (8/68) of the positive farms. From these eight farms, a total of 43 sorbitol-negative E. coli O157:H7 were collected. On five farms, only strains negative for the vt genes were present whereas both vt-negative and vt-positive strains could be detected on three other farms. Further characterization revealed that all isolates carried the eaeA and hlyA genes. Pulsed-field gel electrophoresis (PFGE) of all isolates resulted in nine different PFGE types and within the vt-negative strains, four different genotypes were identified, indicating that certain genetic clones are widespread over the cattle population.
大肠杆菌O157常与出血性结肠炎和溶血尿毒综合征（HUS）相关。志贺毒素被认为是主要的毒力决定因素。然而，最近从HUS患者中分离出了vt阴性的大肠杆菌O157。描述了几种人类传播途径，但牛粪是食物供应和环境被大肠杆菌O157污染的主要来源。在2007年夏季对奶牛场、肉牛场、奶牛/肉牛混合场和犊牛场进行的一项患病率研究中，在11.8%（8/68）的阳性农场中检测到了vt阴性分离株。从这八个农场共收集到43株山梨醇阴性的大肠杆菌O157:H7。在五个农场中，仅存在vt基因阴性的菌株，而在其他三个农场中可同时检测到vt阴性和vt阳性菌株。进一步的特性分析表明，所有分离株均携带eaeA和hlyA基因。对所有分离株进行脉冲场凝胶电泳（PFGE），结果显示有九种不同的PFGE类型，在vt阴性菌株中鉴定出四种不同的基因型，这表明某些基因克隆在牛群中广泛存在。
