Sekse Camilla, Muniesa Maite, Wasteson Yngvild
Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway.
Foodborne Pathog Dis. 2008 Dec;5(6):801-10. doi: 10.1089/fpd.2008.0130.
One of the main virulence factors produced by Shiga toxin-producing Escherichia coli is the Shiga toxin (Stx), which is encoded on lambdoid phages (Stx phage). In Norway, an outbreak of hemorrhagic colitis and hemolytic uremic syndrome (HUS) caused by E. coli O103:H25 was reported during the winter of 2006, but stx(2)-positive isolates were only retrieved from two human samples.
Isolates of E. coli O103:H25 from patients with HUS in Norway, including sporadic cases and the outbreak cases, were investigated for the presence of phages encoding stx(2). The induced Stx phages were characterized morphologically and genetically, and the host susceptibility for these phages of various E. coli O103 isolates, including O103:H25 stx(2) negative isolates from the outbreak, was tested by a plaque assay.
The Stx2 phages in this study are very closely related in terms of morphology, sequence identity, and host infectivity. There may be a conserved phage within the E. coli O103:H25 population.
It is proposed that the Stx2 phage, present in the environment either as free phage particles or within a limited pool of Stx-producing E. coli O103 strains, have infected or integrated in the stx(2)-negative E. coli O103:H25 isolates from the Norwegian outbreak.
产志贺毒素大肠杆菌产生的主要毒力因子之一是志贺毒素（Stx），其由λ样噬菌体（Stx噬菌体）编码。2006年冬季，挪威报告了一起由大肠杆菌O103:H25引起的出血性结肠炎和溶血尿毒综合征（HUS）疫情，但stx(2)阳性分离株仅从两份人类样本中获得。
对挪威HUS患者（包括散发病例和疫情病例）的大肠杆菌O103:H25分离株进行检测，以确定是否存在编码stx(2)的噬菌体。对诱导产生的Stx噬菌体进行形态学和遗传学特征分析，并通过噬菌斑试验检测包括疫情中O103:H25 stx(2)阴性分离株在内的各种大肠杆菌O103分离株对这些噬菌体的宿主易感性。
本研究中的Stx2噬菌体在形态、序列同一性和宿主感染性方面密切相关。大肠杆菌O103:H25群体中可能存在一种保守的噬菌体。
有人提出，环境中以游离噬菌体颗粒形式或存在于有限数量的产Stx大肠杆菌O103菌株中的Stx2噬菌体，已感染或整合到挪威疫情中stx(2)阴性的大肠杆菌O103:H25分离株中。
