Avery S M, Liebana E, Reid C-A, Woodward M J, Buncic S
Division of Food Animal Science, Department of Clinical Veterinary Science, University of Bristol, Langford, United Kingdom.
J Clin Microbiol. 2002 Aug;40(8):2806-12. doi: 10.1128/JCM.40.8.2806-2812.2002.
Two genetic fingerprinting techniques, pulsed-field gel electrophoresis (PFGE) and ribotyping, were used to characterize 207 Escherichia coli O157 isolates from food animals, foods of animal origin, and cases of human disease (206 of the isolates were from the United Kingdom). In addition, 164 of these isolates were also phage typed. The isolates were divided into two general groups: (i) unrelated isolates not known to be epidemiologically linked (n = 154) and originating from food animals, foods and the environment, or humans and (ii) epidemiologically related isolates (n = 53) comprised of four related groups (RGs) originating either from one farm plus the abattoir where cattle from that farm were slaughtered or from one of three different English abattoirs. PFGE was conducted with the restriction endonuclease XbaI, while for ribotyping, two restriction endonucleases (PstI and SphI) were combined to digest genomic DNAs simultaneously. The 207 E. coli O157 isolates produced 97 PFGE profiles and 51 ribotypes. The two genetic fingerprinting methods had similar powers to discriminate the 154 epidemiologically unrelated E. coli O157 isolates in the study (Simpson's index of diversity [D] = 0.98 and 0.94 for PFGE typing and ribotyping, respectively). There was no correlation between the source of an isolate (healthy meat or milk animals, retail meats, or cases of human infection) and either particular PFGE or ribotype profiles or clusters. Combination of the results of both genetic fingerprinting methods produced 146 types, significantly more than when either of the two methods was used individually. Consequently, the superior discriminatory performance of the PFGE-ribotyping combination was proven in two ways: (i) by demonstrating that the majority of the E. coli O157 isolates with unrelated histories were indeed distinguishable types and (ii) by identifying some clonal groups among two of the four RGs of E. coli O157 isolates (comprising PFGE types different by just one or two bands), the relatedness of which would have remained unconfirmed otherwise.
运用两种基因指纹技术，即脉冲场凝胶电泳（PFGE）和核糖体分型，对来自食用动物、动物源性食品及人类疾病病例的207株大肠杆菌O157分离株进行特征分析（其中206株分离株来自英国）。此外，还对其中164株分离株进行了噬菌体分型。这些分离株分为两大类：（i）已知无流行病学关联的不相关分离株（n = 154），其来源包括食用动物、食品和环境或人类；（ii）流行病学相关分离株（n = 53），由四个相关组（RGs）组成，这些组要么来自一个农场及其屠宰该农场牛的屠宰场，要么来自三个不同的英国屠宰场之一。PFGE采用限制性内切酶XbaI进行，而核糖体分型则将两种限制性内切酶（PstI和SphI）联合使用以同时消化基因组DNA。这207株大肠杆菌O157分离株产生了97种PFGE图谱和51种核糖体分型。在该研究中，这两种基因指纹方法区分154株无流行病学关联的大肠杆菌O157分离株的能力相似（PFGE分型和核糖体分型的辛普森多样性指数[D]分别为0.98和0.94）。分离株的来源（健康的肉用或乳用动物、零售肉类或人类感染病例）与特定的PFGE或核糖体分型图谱或聚类之间均无相关性。两种基因指纹方法的结果相结合产生了146种类型，显著多于单独使用两种方法中的任何一种时的类型数。因此，PFGE - 核糖体分型组合的卓越鉴别性能通过两种方式得到证明：（i）证明大多数具有不相关历史的大肠杆菌O157分离株确实是可区分的类型；（ii）在大肠杆菌O157分离株的四个RGs中的两个中识别出一些克隆组（其PFGE类型仅相差一两条带），否则它们之间的相关性将无法得到确认。
