Thilakarathna Surangi H, Parsons Brendon, Chui Linda
Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 1C9, Canada.
Alberta Precision Laboratories-Public Health Laboratory (ProvLab), Edmonton, AB T6G 2J2, Canada.
Toxins (Basel). 2025 May 27;17(6):267. doi: 10.3390/toxins17060267.
Early determination of the Shiga toxin type of Shiga toxin-producing (STEC) is crucial for guiding STEC-infected patients for proper and timely treatment and patient care. Most diagnostic microbiology laboratories rely on PCR assays to detect the presence of and/or and enzymatic immunoassays (EIA) to detect the presence of the Shiga toxins 1 and/or 2 in STEC-positive stool samples. Occasionally, the stool samples test positive for STEC by PCR assays but test negative for the presence of Shiga toxins. Insufficient toxin production under laboratory conditions is the main culprit of this discordance. To test whether EIA-based STEC detection could be improved, various clinical STEC strains were treated with mitomycin C, which is a commonly used inducer of Shiga toxin production. A dose-dependent increase in Shiga toxin production, in response to mitomycin C doses of up to 500 ng/mL, was observed without any bactericidal effects. Depending on the serotype, 5-50 times more Shiga toxin 2 was produced than Shiga toxin 1. Shiga toxin production was not induced by the mitomycin C treatment in certain STEC serotypes carrying the toxin subtypes , , , , . This diversity in toxin production indicates that other factors may determine toxin expression in certain STEC strains, which warrant further exploration.
早期确定产志贺毒素大肠杆菌（STEC）的志贺毒素类型对于指导STEC感染患者进行恰当且及时的治疗及护理至关重要。大多数诊断微生物实验室依靠聚合酶链反应（PCR）检测来确定是否存在 及/或 ，并通过酶免疫测定（EIA）来检测STEC阳性粪便样本中志贺毒素1和/或2的存在情况。偶尔，粪便样本通过PCR检测呈STEC阳性，但志贺毒素检测呈阴性。实验室条件下毒素产生不足是这种不一致的主要原因。为了测试基于EIA的STEC检测是否可以改进，用丝裂霉素C处理了各种临床STEC菌株，丝裂霉素C是一种常用的志贺毒素产生诱导剂。观察到随着丝裂霉素C剂量增加至500 ng/mL，志贺毒素产量呈剂量依赖性增加，且没有任何杀菌作用。根据血清型，志贺毒素2的产量比志贺毒素1多5至50倍。在携带毒素亚型 、 、 、 、 的某些STEC血清型中，丝裂霉素C处理未诱导志贺毒素产生。毒素产生的这种多样性表明，其他因素可能决定某些STEC菌株中的毒素表达，这值得进一步探索。
