Gilmour Matthew W, Tracz Dobryan M, Andrysiak Ashleigh K, Clark Clifford G, Tyson Shari, Severini Alberto, Ng Lai-King
National Microbiology Laboratory, 1015 Arlington Street, Winnipeg, Manitoba, Canada.
J Clin Microbiol. 2006 Feb;44(2):449-58. doi: 10.1128/JCM.44.2.449-458.2006.
Infections with Shiga toxin-producing Escherichia coli (STEC) result in frequent cases of sporadic and outbreak-associated enteric bacterial disease in humans. Classification of STEC is by stx genotype (encoding the Shiga toxins), O and H antigen serotype, and seropathotype (subgroupings based upon the clinical relevance and virulence-related genotypes of individual serotypes). The espZ gene is encoded in the locus of enterocyte effacement (LEE) pathogenicity island responsible for the attaching and effacing (A/E) lesions caused by various E. coli pathogens (but not limited to STEC), and this individual gene ( approximately 300 bp) has previously been identified as hypervariable among these A/E pathogens. Sequence analysis of the espZ locus encoded by additional STEC serotypes and strains (including O26:H11, O121:H19, O111:NM, O145:NM, O165:H25, O121:NM, O157:NM, O157:H7, and O5:NM) indicated that distinct sequence variants exist which correlate to subgroups among these serotypes. Allelic discrimination at the espZ locus was achieved using Light Upon eXtension real-time PCR and by liquid microsphere suspension arrays. The allele subtype of espZ did not correlate with STEC seropathotype classification; however, a correlation with the allele type of the LEE-encoded intimin (eae) gene was supported, and these sequence variations were conserved among individual serotypes. The study focused on the characterization of three clinically significant seropathotypes of LEE-positive STEC, and we have used the observed genetic variation at a pathogen-specific locus for detection and subtyping of STEC.
产志贺毒素大肠杆菌（STEC）感染导致人类频繁出现散发性和与暴发相关的肠道细菌病病例。STEC的分类依据stx基因型（编码志贺毒素）、O和H抗原血清型以及血清致病型（基于各血清型的临床相关性和毒力相关基因型进行的亚分组）。espZ基因编码于肠细胞损伤位点（LEE）致病岛，该致病岛负责由各种大肠杆菌病原体（但不限于STEC）引起的紧密黏附与抹平（A/E）损伤，并且这个单独的基因（约300bp）先前已被确定在这些A/E病原体中具有高变异性。对另外一些STEC血清型和菌株（包括O26:H11、O121:H19、O111:NM、O145:NM、O165:H25、O121:NM、O157:NM、O157:H7和O5:NM）的espZ位点进行序列分析表明，存在与这些血清型中的亚组相关的不同序列变体。利用延伸发光实时PCR和液体微球悬浮阵列实现了espZ位点的等位基因鉴别。espZ的等位基因亚型与STEC血清致病型分类不相关；然而，支持其与LEE编码的紧密黏附素（eae）基因的等位基因类型相关，并且这些序列变异在各血清型中是保守的。该研究聚焦于LEE阳性STEC三种具有临床意义的血清致病型的特征分析，并且我们已利用在病原体特异性位点观察到的遗传变异对STEC进行检测和分型。
