Vali Leila, Wisely Karen A, Pearce Michael C, Turner Esther J, Knight Hazel I, Smith Alastair W, Amyes Sebastian G B
Medical Microbiology, University of Edinburgh, Medical School, Teviot Place, Edinburgh EH8 9AG, UK.
Appl Environ Microbiol. 2004 Oct;70(10):5947-54. doi: 10.1128/AEM.70.10.5947-5954.2004.
Escherichia coli O157:H7 is a human pathogen that is carried and transmitted by cattle. Scotland is known to have one of the highest rates of E. coli O157 human infections in the world. Two hundred ninety-three isolates were obtained from naturally infected cattle and the environment on two farms in the Scottish Highlands. The isolates were typed by pulsed-field gel electrophoresis (PFGE) with XbaI restriction endonuclease enzyme, and 19 different variations in patterns were found. There was considerable genomic diversity within the E. coli O157 population on the two farms. The PFGE pattern of one of the observed subtypes matched exactly with that of a strain obtained from a Scottish patient with hemolytic-uremic syndrome. To examine the stability of an individual E. coli O157 strain, continuous subculturing of a strain was performed 110 times. No variation from the original PFGE pattern was observed. We found three indistinguishable subtypes of E. coli O157 on both study farms, suggesting common sources of infection. We also examined the antibiotic resistance of the isolated strains. Phenotypic studies demonstrated resistance of the strains to sulfamethoxazole (100%), chloramphenicol (3.07%), and at a lower rate, other antibiotics, indicating the preservation of antibiotic sensitivity in a rapidly changing population of E. coli O157.
大肠杆菌O157:H7是一种由牛携带并传播的人类病原体。众所周知，苏格兰是世界上大肠杆菌O157人类感染率最高的地区之一。从苏格兰高地两个农场的自然感染牛和环境中获得了293株分离株。使用XbaI限制性内切酶通过脉冲场凝胶电泳（PFGE）对分离株进行分型，发现了19种不同的图谱变化。两个农场的大肠杆菌O157群体内存在相当大的基因组多样性。观察到的一种亚型的PFGE图谱与从一名患有溶血性尿毒症综合征的苏格兰患者身上获得的菌株的图谱完全匹配。为了检查单个大肠杆菌O157菌株的稳定性，对一个菌株进行了110次连续传代培养。未观察到与原始PFGE图谱的差异。我们在两个研究农场都发现了三种无法区分的大肠杆菌O157亚型，表明存在共同的感染源。我们还检查了分离菌株的抗生素耐药性。表型研究表明，这些菌株对磺胺甲恶唑（100%）、氯霉素（3.07%）以及较低比例的其他抗生素具有耐药性，这表明在快速变化的大肠杆菌O157群体中抗生素敏感性得以保留。
