Cytolethal distending toxin (CDT)-producing Escherichia coli have been isolated from patients with diarrhea, sepsis and urinary tract infection. CDT of E. coli is divided into five types (CDT-I through CDT-V) based on differences in amino acid sequences and its genomic location. However, in our recent studies, a few strains of cdt-II gene-positive bacteria, initially identified as atypical E. coli, were re-identified as Escherichia albertii, an emerging enteropathogen, by extensive characterization including multilocus sequence (MLS) analysis and sugar utilization tests. This finding prompted us to investigate if bacteria previously identified as cdt-II gene-positive E. coli might be E. albertii. In the present study, we therefore re-examined the identity of 20 cdt-II gene-positive bacteria isolated from children with diarrhea, which were initially identified as atypical E. coli. By extensive sugar utilization tests, these bacteria showed a closer relatedness to E. albertii than E. coli, because they did not ferment any of the tested sugars including dulcitol, lactose, d-melibiose, l-rhamnose and d-xylose. Further, both phylogenetic analyses based on nucleotide sequences of 7 housekeeping genes (MLS analysis) and rpoB gene showed that all the cdt-II gene-positive bacteria belonged to a distinct lineage of E. albertii from those of E. coli and Shigella boydii. They were also positive by an E. albertii-specific PCR. Taken together, these data suggest that cdt-II gene-positive bacteria previously identified as E. coli are actually E. albertii. Therefore, we suggest a new definition for cdt-II gene-positive E. coli as E. albertii with the inclusion of CDT-II in E. albertii CDT.

中文翻译：

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细胞致死性毒素II基因阳性大肠埃希氏菌与新兴的肠病原体艾氏埃希氏菌的关联。

已经从腹泻，败血症和尿路感染的患者中分离出了产生细胞致死性扩张毒素（CDT）的大肠杆菌。根据氨基酸序列及其基因组位置的差异，大肠杆菌的CDT分为五种类型（CDT-1至CDT-V）。然而，在我们最近的研究中，通过广泛的鉴定（包括多基因座序列（MLS）分析和鉴定），最初鉴定为非典型大肠杆菌的少数cdt-II基因阳性细菌菌株被重新鉴定为新兴的肠病原体埃希氏菌。糖利用测试。这一发现促使我们调查以前鉴定为cdt-II基因阳性大肠杆菌的细菌是否为艾伯氏大肠杆菌。因此，在本研究中，我们重新检查了从腹泻儿童中分离出的20种cdt-II基因阳性细菌的身份，最初被鉴定为非典型大肠杆菌。通过广泛的糖利用测试，这些细菌显示出与大肠埃希氏菌比大肠杆菌更紧密的关联，因为它们没有发酵任何被测糖，包括二糖醇，乳糖，D-半乳糖，L-鼠李糖和D-木糖。此外，基于7个管家基因和rpoB基因的核苷酸序列的系统发育分析均显示，所有cdt-II基因阳性细菌均属于与大肠杆菌和博伊氏志贺氏菌不同的艾伯特氏菌谱系。它们还通过艾伯氏大肠杆菌特异性PCR呈阳性。综上所述，这些数据表明先前鉴定为大肠杆菌的cdt-II基因阳性细菌实际上是艾伯氏大肠杆菌。因此，我们为cdt-II基因阳性的大肠杆菌提出了一个新的定义，即E. albertii大肠杆菌，其中包含CDT-II。