Chase-Topping Margo E, McKendrick Iain J, Pearce Michael C, MacDonald Peter, Matthews Louise, Halliday Jo, Allison Lesley, Fenlon Dave, Low J Christopher, Gunn George, Woolhouse Mark E J
Centre for Infectious Diseases, University of Edinburgh, Edinburgh, United Kingdom.
J Clin Microbiol. 2007 May;45(5):1594-603. doi: 10.1128/JCM.01690-06. Epub 2007 Mar 14.
Escherichia coli O157 infections are the cause of sporadic or epidemic cases of often bloody diarrhea that can progress to hemolytic uremic syndrome (HUS), a systematic microvascular syndrome with predominantly renal and neurological complications. HUS is responsible for most deaths associated with E. coli O157 infection. From March 2002 to February 2004, approximately 13,000 fecal pat samples from 481 farms with finishing/store cattle throughout Scotland were examined for the presence of E. coli O157. A total of 441 fecal pats from 91 farms tested positive for E. coli O157. From the positive samples, a point estimate for high-level shedders was identified using mixture distribution analysis on counts of E. coli O157. Models were developed based on the confidence interval surrounding this point estimate (high-level shedder, greater than 10(3) or greater than 10(4) CFU g(-1) feces). The mean prevalence on high-level-shedding farms was higher than that on low-level-shedding farms. The presence of a high-level shedder on a farm was found to be associated with a high proportion of low-level shedding, consistent with the possibility of a higher level of transmission. Analysis of risk factors associated with the presence of a high-level shedder on a farm suggested the importance of the pathogen and individual host rather than the farm environment. The proportion of high-level shedders of phage 21/28 was higher than expected by chance. Management-related risk factors that were identified included the type of cattle (female breeding cattle) and cattle stress (movement and weaning), as opposed to environmental factors, such as water supply and feed.
大肠杆菌O157感染是散发性或流行性病例中常出现血性腹泻的病因，这种腹泻可能会发展为溶血性尿毒综合征（HUS），这是一种系统性微血管综合征，主要伴有肾脏和神经并发症。HUS是与大肠杆菌O157感染相关的大多数死亡的原因。2002年3月至2004年2月，对苏格兰各地481个有育肥牛/存栏牛的农场的约13000份粪便样本进行了检测，以确定是否存在大肠杆菌O157。共有来自91个农场的441份粪便样本检测出大肠杆菌O157呈阳性。从阳性样本中，通过对大肠杆菌O157计数进行混合分布分析，确定了高排泄量动物的点估计值。基于围绕该点估计值的置信区间（高排泄量动物，大于10³或大于10⁴CFU g⁻¹粪便）建立了模型。高排泄量农场的平均患病率高于低排泄量农场。发现农场中存在高排泄量动物与低排泄量动物的高比例相关，这与更高水平传播的可能性一致。对与农场中存在高排泄量动物相关的风险因素分析表明，病原体和个体宿主而非农场环境很重要。噬菌体21/28高排泄量动物的比例高于偶然预期。确定的与管理相关的风险因素包括牛的类型（雌性繁殖牛）和牛的应激（移动和断奶），而非环境因素，如水供应和饲料。
