Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogens, known to cause enteric infections especially diarrhea, mainly attributed to Shiga toxins (Stxs). The use of certain antibiotics for treating this infection is controversial, owing to an increased risk for producing Stxs (Stx 1 and Stx 2). Increased antibiotic resistance is also thought to be involved in the pathogenesis of STEC diseases. The purpose of this study was to analyze the effects of antibiotics on induction of Stx 1 and Stx 2 in clinical STEC isolates and to investigate the relationships between increased resistance and Stx production. Fifteen clinical isolates were treated with sub minimum inhibitory concentrations (Sub MIC) of clinically used antibiotics (ciprofloxacin, fosfomycin, tigecycline, and meropenem), and the changes in expression levels of stx1 and stx2 genes were estimated using qRT-PCR. The expressions of Shiga toxins were found to be increased up to 6.5- and eightfold under ciprofloxacin and tigecycline Sub MIC, respectively. Fosfomycin had weak induction effect of up to twofold, whereas meropenem had the weakest influence on such expression. Resistant isolates were found to be more prone to increased expression of toxins.

产志贺毒素 大肠杆菌 (STEC) 是一种重要的食源性病原体，已知会引起肠道感染，尤其是腹泻，主要归因于志贺毒素 (Stxs)。由于产生 Stxs（Stx 1 和 Stx 2）的风险增加，使用某些抗生素治疗这种感染是有争议的。增加的抗生素耐药性也被认为与 STEC 疾病的发病机制有关。本研究的目的是分析抗生素对临床 STEC 分离株中 Stx 1 和 Stx 2 诱导的影响，并研究耐药性增加与 Stx 产生之间的关系。15 株临床分离株用亚最低抑菌浓度 (Sub MIC) 的临床使用抗生素（环丙沙星、磷霉素、替加环素和美罗培南）处理，stx1表达水平的变化和stx2基因使用 qRT-PCR 估计。发现志贺毒素的表达在环丙沙星和替加环素亚 MIC 下分别增加了 6.5 倍和 8 倍。磷霉素具有高达两倍的弱诱导作用，而美罗培南对这种表达的影响最弱。发现抗性分离株更容易增加毒素的表达。