Institute for Hygiene and the National Consulting Laboratory on Hemolytic Uremic Syndrome, University of Münster, Wernigerode, Germany.
Clin Infect Dis. 2013 May;56(10):1373-81. doi: 10.1093/cid/cit055. Epub 2013 Feb 1.
Enterohemorrhagic Escherichia coli (EHEC) O26 causes diarrhea and hemolytic uremic syndrome (HUS). Strains harboring the stx1a gene prevail, but strains with stx2a as the sole Shiga toxin-encoding gene are now emerging. The traits and virulence of the latter set of strains are unknown. We correlated stx genotypes of 272 EHEC O26 strains isolated in 7 European countries between 1996 and 2012 with disease phenotypes. We determined phylogeny, clonal structure, and plasmid gene profiles of the isolates and portray geographic and temporal distribution of the different subgroups.
The stx genotypes and plasmid genes were identified using polymerase chain reaction, phylogeny was assigned using multilocus sequence typing, and clonal relatedness was established using pulsed-field gel electrophoresis.
Of the 272 EHEC O26 isolates, 107 (39.3%), 139 (51.1%), and 26 (9.6%) possessed stx1a, stx2a, or both genes, respectively. Strains harboring stx2a only were significantly associated with HUS (odds ratio, 14.2; 95% confidence interval, 7.9-25.6; P < .001) compared to other stx genotypes. The stx2a-harboring strains consist of 2 phylogenetically distinct groups defined by sequence type (ST) 21 and ST29. The ST29 strains are highly conserved and correspond by plasmid genes to the new virulent clone of EHEC O26 that emerged in Germany in the 1990s. This new clone occurred in 6 of the 7 countries and represented approximately 50% of all stx2a-harboring EHEC O26 strains isolated between 1996 and 2012.
A new highly virulent clone of EHEC O26 has emerged in Europe. Its reservoirs and sources warrant identification.
肠出血性大肠杆菌（EHEC）O26 引起腹泻和溶血性尿毒症综合征（HUS）。目前，携带 stx1a 基因的菌株占主导地位，但现在也出现了仅携带 stx2a 作为唯一志贺毒素编码基因的菌株。后者的特性和毒力尚不清楚。我们将 1996 年至 2012 年间在 7 个欧洲国家分离的 272 株 EHEC O26 菌株的 stx 基因型与疾病表型相关联。我们确定了分离株的系统发育、克隆结构和质粒基因谱，并描绘了不同亚组的地理和时间分布。
使用聚合酶链反应鉴定 stx 基因型和质粒基因，使用多位点序列分型分配系统发育，使用脉冲场凝胶电泳确定克隆相关性。
在 272 株 EHEC O26 分离株中，分别有 107 株（39.3%）、139 株（51.1%）和 26 株（9.6%）携带 stx1a、stx2a 或两者的基因。与其他 stx 基因型相比，仅携带 stx2a 的菌株与 HUS 显著相关（比值比，14.2；95%置信区间，7.9-25.6；P<0.001）。携带 stx2a 的菌株由通过序列型（ST）21 和 ST29 定义的 2 个具有不同系统发育的组组成。ST29 菌株高度保守，通过质粒基因与 20 世纪 90 年代在德国出现的 EHEC O26 的新型高毒克隆相对应。该新克隆出现在 7 个国家中的 6 个国家，占 1996 年至 2012 年间分离的所有携带 stx2a 的 EHEC O26 菌株的约 50%。
欧洲出现了一种新型高毒的 EHEC O26 克隆。其储存库和来源值得确定。
