E. coli Reference Laboratory-LREC, Department of Microbiology and Parasitology, Faculty of Veterinary Science, University of Santiago de Compostela-USC, Lugo, Spain.
Int Microbiol. 2011 Sep;14(3):121-41. doi: 10.2436/20.1501.01.142.
A Shiga-toxin-producing Escherichia coli (STEC) strain belonging to serotype O104:H4, phylogenetic group B1 and sequence type ST678, with virulence features common to the enteroaggregative E. coli (EAEC) pathotype, was reported as the cause of the recent 2011 outbreak in Germany. The outbreak strain was determined to carry several virulence factors of extraintestinal pathogenic E. coli (ExPEC) and to be resistant to a wide range of antibiotics. There are only a few reports of serotype O104:H4, which is very rare in humans and has never been detected in animals or food. Several research groups obtained the complete genome sequence of isolates of the German outbreak strain as well as the genome sequences of EAEC of serotype O104:H4 strains from Africa. Those findings suggested that horizontal genetic transfer allowed the emergence of the highly virulent Shiga-toxin-producing enteroaggregative E. coli (STEAEC) O104:H4 strain responsible for the outbreak in Germany. Epidemiologic investigations supported a linkage between the outbreaks in Germany and France and traced their origin to fenugreek seeds imported from Africa. However, there has been no isolation of the causative strain O104:H4 from any of the samples of fenugreek seeds analyzed. Following the German outbreak, we conducted a large sampling to analyze the presence of STEC, EAEC, and other types of diarrheagenic E. coli strains in Spanish vegetables. During June and July 2011, 200 vegetable samples from different origins were analyzed. All were negative for the virulent serotype O104:H4 and only one lettuce sample (0.6%) was positive for a STEC strain of serotype O146:H21 (stx1, stx2), considered of low virulence. Despite the single positive case, the hygienic and sanitary quality of Spanish vegetables proved to be quite good. In 195 of the 200 samples (98%), <10 colony-forming units (cfu) of E. coli per gram were detected, and the microbiological levels of all samples were satisfactory (<100 cfu/g). The samples were also negative for other pathotypes of diarrheagenic E. coli (EAEC, ETEC, tEPEC, and EIEC). Consistent with data from other countries, STEC belonging to serotype O157:H7 and other serotypes have been isolated from beef, milk, cheese, and domestic (cattle, sheep, goats) and wild (deer, boar, fox) animals in Spain. Nevertheless, STEC outbreaks in Spain are rare.
一株产志贺毒素的大肠杆菌（STEC）菌株属于血清型 O104:H4、B1 进化群和 ST678 序列型，具有肠聚集性大肠杆菌（EAEC）病原型的常见毒力特征，被报告为德国 2011 年近期暴发的原因。该暴发菌株被确定携带多种肠外致病性大肠杆菌（ExPEC）的毒力因子，并对多种抗生素具有耐药性。血清型 O104:H4 非常罕见，在人类中从未检测到，也从未在动物或食物中检测到，仅有少数报道。几个研究小组获得了德国暴发菌株的全基因组序列以及来自非洲的 O104:H4 血清型 EAEC 菌株的基因组序列。这些发现表明，水平基因转移允许高毒力产志贺毒素肠聚集性大肠杆菌（STEAEC）O104:H4 菌株的出现，该菌株导致了德国的暴发。流行病学调查支持德国和法国暴发之间的联系，并追溯到从非洲进口的葫芦巴种子。然而，在分析的任何葫芦巴种子样本中都没有分离出致病菌株 O104:H4。在德国暴发之后，我们进行了大规模抽样，以分析西班牙蔬菜中存在的 STEC、EAEC 和其他类型的腹泻性大肠杆菌菌株。2011 年 6 月至 7 月期间，分析了来自不同来源的 200 个蔬菜样本。所有样本均为强毒血清型 O104:H4 阴性，仅 1 份生菜样本（0.6%）为低毒力的血清型 O146:H21（stx1、stx2）产志贺毒素 STEC 菌株阳性。尽管只有 1 例阳性病例，但西班牙蔬菜的卫生和安全质量相当好。在 200 个样本中的 195 个（98%）样本中，每克大肠杆菌菌落形成单位（cfu）<10，所有样本的微生物水平均令人满意（<100 cfu/g）。样本还对其他腹泻性大肠杆菌（EAEC、ETEC、tEPEC 和 EIEC）的病原型均为阴性。与其他国家的数据一致，西班牙已从牛肉、牛奶、奶酪以及家养（牛、羊、山羊）和野生（鹿、野猪、狐狸）动物中分离出属于血清型 O157:H7 和其他血清型的 STEC。然而，西班牙的 STEC 暴发很少见。
