McAdoo K K, Carson C A
Department of Veterinary Pathobiology, University of Missouri-Columbia 65211, USA.
Adv Exp Med Biol. 1997;412:193-200. doi: 10.1007/978-1-4899-1828-4_28.
Escherichia coli O157:H7 has been recognized since 1982 as a serious human pathogen spread by contaminated food and water. Pulsed-field gel electrophoresis has proven useful for identification of specific isolates/strains of this organism. Hemolytic uremic syndrome (HUS), generally occurring in children or the aged, is the most severe sequela associated with E. coli O157:H7 infection. The presently described work was designed to compare the genomic profile of isolates known to have caused HUS with those having had no such involvement. We asked the question: "Can we develop the means to recognize an 'HUS-prone' E. coli isolate and thereby alert medical personnel to the increased risk?" Twenty-two HUS-related and 10 HUS-unrelated E. coli O157:H7 samples were chosen for genomic analysis. Isolates were cultured overnight prior to being embedded in agarose gel plugs. Plugs were digested, using Xbal restriction endonuclease, and subjected to pulsed-field gel electrophoresis (PFGE) for 20 hours. Gels were stained with ethidium bromide, photographed under ultraviolet light, and Southern blotted. Radiolabeled toxin gene probes were used for hybridization assays. The two classes of isolates were compared by optical imaging software. A computer-generated dendrogram, based on restriction profiles, offered strong initial evidence that the HUS sequela may be produced by a particularly virulent and identifiable clone. The predictive value of this finding appears to be substantial.
自1982年以来，肠出血性大肠杆菌O157:H7被公认为是一种通过受污染的食物和水传播的严重人类病原体。脉冲场凝胶电泳已被证明可用于鉴定该生物体的特定分离株/菌株。溶血性尿毒症综合征（HUS）通常发生在儿童或老年人中，是与大肠杆菌O157:H7感染相关的最严重后遗症。目前所描述的工作旨在比较已知导致HUS的分离株与未发生此类情况的分离株的基因组图谱。我们提出了一个问题：“我们能否开发出识别‘易患HUS’的大肠杆菌分离株的方法，从而提醒医务人员注意这种增加的风险？”选择了22个与HUS相关和10个与HUS无关的大肠杆菌O157:H7样本进行基因组分析。分离株在嵌入琼脂糖凝胶块之前培养过夜。使用Xbal限制性内切酶消化凝胶块，并进行20小时的脉冲场凝胶电泳（PFGE）。凝胶用溴化乙锭染色，在紫外线下拍照，然后进行Southern印迹。用放射性标记的毒素基因探针进行杂交试验。通过光学成像软件比较这两类分离株。基于限制性图谱的计算机生成的树状图提供了有力的初步证据，表明HUS后遗症可能由一种特别有毒且可识别的克隆产生。这一发现的预测价值似乎很大。
