Laboratorio de Enterobacterias, Servicio de Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Madrid, Spain.
Vet Microbiol. 2012 Oct 12;159(3-4):531-5. doi: 10.1016/j.vetmic.2012.04.036. Epub 2012 May 3.
Shiga toxin-producing Escherichia coli (STEC) O128:H2 is recognised worldwide to be an important non-O157 STEC associated with human illness and in particular with causing haemolytic uraemic syndrome. This serotype is commonly isolated from sheep and is being increasingly isolated from deer. We determined the virulence profile and genetic relationships of one human, six sheep and five deer intimin-negative STEC O128:H2 strains isolated in Spain over a 7-year period. Our goals were to establish the presence of other virulence-associated factors, such as SubAB, in intimin-negative STEC O128:H2 strains involved in human disease and in that case, to determine if sheep and/or deer represent a reservoir of SubAB-positive STEC O128:H2. All the strains lacked the eae gene and carried subtilase cytotoxin (SubAB) encoding genes (subAB) and tia genes, but not saa gene, suggesting the presence of the recently identified new variant of SubAB, encoded on a putative pathogenicity island together with tia. We report for the first time the presence of subtilase cytotoxin encoding genes in intimin-negative STEC O128:H2 strains pathogenic for humans and how this finding might explain their clinical relevance despite neither carrying eae nor stx subtypes associated with severe clinical outcomes, but only stx1c and stx2b. Multilocus sequence typing analysis revealed that STEC O128:H2 strains from sheep and deer belong to the clonal lineage of STEC O128:H2 strains involved in diarrhoeal and haemorrhagic diseases in humans. Our results indicate that sheep and deer represent a reservoir of SubAB-positive STEC O128:H2 strains and thus a potential source of human infection.
产志贺毒素大肠杆菌（STEC）O128：H2 在世界范围内被认为是一种与人类疾病相关的重要非 O157 STEC，特别是与溶血性尿毒综合征有关。这种血清型通常从绵羊中分离出来，并且越来越多地从鹿中分离出来。我们确定了在西班牙 7 年内分离出的 1 个人类、6 只绵羊和 5 只鹿的 6 种不耐[intimin]阴性 STEC O128：H2 菌株的毒力谱和遗传关系。我们的目标是确定其他与毒力相关的因素（如 SubAB）在耐[intimin]阴性 STEC O128：H2 菌株中的存在情况，这些菌株与人类疾病有关，在这种情况下，确定绵羊和/或鹿是否代表 SubAB 阳性 STEC O128：H2 的储库。所有菌株均缺乏 eae 基因，并携带枯草杆菌蛋白酶细胞毒素（SubAB）编码基因（subAB）和 tia 基因，但不携带 saa 基因，表明存在最近发现的 SubAB 新变体，该变体与 tia 一起编码在一个假定的致病性岛上。我们首次报告了耐[intimin]阴性 STEC O128：H2 菌株中存在枯草杆菌蛋白酶细胞毒素编码基因，以及这一发现如何解释它们的临床相关性，尽管这些菌株既不携带与严重临床结果相关的 eae 基因也不携带 stx 亚型，但仅携带 stx1c 和 stx2b。多位点序列分型分析显示，来自绵羊和鹿的 STEC O128：H2 菌株属于与人类腹泻和出血性疾病相关的 STEC O128：H2 菌株的克隆谱系。我们的结果表明，绵羊和鹿是 SubAB 阳性 STEC O128：H2 菌株的储库，因此是人类感染的潜在来源。
