Shiga Toxin, Cytolethal Distending Toxin, and Hemolysin Repertoires in Clinical Escherichia coli O91 Isolates
Shiga Toxin, Cytolethal Distending Toxin, and Hemolysin Repertoires in Clinical Escherichia coli O91 Isolates
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DOI：
10.1128/jcm.00201-09
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发表时间：
2009-07-01
影响因子：
9.4
通讯作者：
Friedrich, Alexander W.
中科院分区：
文献类型：
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作者：
Bielaszewska, Martina;Stoewe, Franziska;Friedrich, Alexander W.
O91 血清群的产志贺毒素 (Stx) 大肠杆菌 (STEC) 菌株是最常见的人类致病性 eae 阴性 STEC 菌株。为了便于对这些病原体进行诊断和分型，我们对 100 个临床 STEC O91 分离株进行了基因型和表型特征分析。运动菌株表达鞭毛抗原 H8（1 株）、H10（2 株）、H14（52 株）和 H21（20 株）或 H 不可分型（Hnt）（10 株）； 15株不能运动。所有非运动菌株和 Hnt 菌株都拥有编码 H14 抗原鞭毛蛋白亚基 (fliC H14) 的 fliC 基因。大多数 STEC O91 菌株具有肠出血性大肠杆菌 hlyA 并表达肠溶血表型。在鉴定的七个 stx 等位基因中，编码粘液和弹性蛋白酶可激活 Stx2d 的 stx(2dact) 仅存在于 STEC O91: H21 中，而其他血清型的大多数菌株都具有 stx(1)。此外，只有 STEC O91: H21 拥有 cdt-V 簇，编码细胞致死膨胀毒素 V；该毒素有规律地表达，对人类微血管内皮细胞具有致命性。 STEC O91：H21 感染与溶血性尿毒症综合征相关（P = 0.0015），而其他血清型菌株主要起源于非血性腹泻患者。我们得出的结论是，STEC O91 临床分离株属于至少四个谱系，这些谱系在 H 抗原/fliC 类型、stx 基因型和非 stx 假定毒力因子方面有所不同，且毒力决定簇在 O91:H21 谱系中积累。在肠溶血素琼脂上从患者粪便中分离 STEC O91，并使用 fliC 基因分型对这些分离株进行快速初步亚型分型，有助于在临床和流行病学研究中识别这些新出现的病原体，并能够预测严重临床结果的风险。
Shiga toxin (Stx)-producing Escherichia coli (STEC) strains of serogroup O91 are the most common human pathogenic eae-negative STEC strains. To facilitate diagnosis and subtyping of these pathogens, we genotypically and phenotypically characterized 100 clinical STEC O91 isolates. Motile strains expressed flagellar antigens H8 (1 strain), H10 (2 strains), H14 (52 strains), and H21 (20 strains) or were H nontypeable (Hnt) (10 strains); 15 strains were nonmotile. All nonmotile and Hnt strains possessed the fliC gene encoding the flagellin subunit of the H14 antigen (fliC H14). Most STEC O91 strains possessed enterohemorrhagic E. coli hlyA and expressed an enterohemolytic phenotype. Among seven stx alleles identified, stx(2dact), encoding mucus-and elastase-activatable Stx2d, was present solely in STEC O91: H21, whereas most strains of the other serotypes possessed stx(1). Moreover, only STEC O91: H21 possessed the cdt-V cluster, encoding cytolethal distending toxin V; the toxin was regularly expressed and was lethal to human microvascular endothelial cells. Infection with STEC O91: H21 was associated with hemolytic-uremic syndrome (P = 0.0015), whereas strains of the other serotypes originated mostly in patients with nonbloody diarrhea. We conclude that STEC O91 clinical isolates belong to at least four lineages that differ by H antigens/fliC types, stx genotypes, and non-stx putative virulence factors, with accumulation of virulence determinants in the O91:H21 lineage. Isolation of STEC O91 from patients' stools on enterohemolysin agar and the rapid initial subtyping of these isolates using fliC genotyping facilitate the identification of these emerging pathogens in clinical and epidemiological studies and enable prediction of the risk of a severe clinical outcome.