The latex agglutination test using single-chain antibody fragments (scFvStx1 and scFvStx2) coupled to latex particles, was compared with the gold standard Vero cell assay for Shiga toxin (Stx) detection, aiming to estimate the diagnosis potential of these scFv fragments in a rapid and straightforward test. The latex complexes identified the presence of the toxins up to a 1:8 dilution in the majority of the evaluated strains. Moreover, the Stx concentration was indirectly determined in Stx-producing Escherichia coli (STEC) strains, allowing detection limit inference. A Stx dilution curve was constructed, and the data was analyzed in a non-linear model by second-order polynomial regression for prediction (p-value of 0.001 and a R² above 0.98 were considered for correlations). The detection limit was 30 ng/mL for Stx1 and 10 ng/mL for Stx2. The scFvStx1 and scFvStx2 coupled to latex nanoparticles provide a toxin assay with a competitive Stx detection limit, which has a low cost and short execution time. The diagnostic method proposed here, using, for the first time, recombinant antibody fragments, raises the possibility of developing a more affordable test to be used in the routine detection and surveillance of STEC infections.

使用与乳胶颗粒偶联的单链抗体片段（scFvStx1和scFvStx2）进行的乳胶凝集测试与用于志贺毒素（Stx）检测的金标准Vero细胞测定法进行了比较，旨在快速评估这些scFv片段的诊断潜力和简单的测试。乳胶复合物在大多数评估菌株中鉴定出毒素的存在，稀释度高达1：8。此外，在产生Stx的大肠杆菌（STEC）菌株中间接确定了Stx浓度，从而可以推断出检测限。绘制了Stx稀释曲线，并通过二阶多项式回归在非线性模型中分析了数据，以进行预测（p值为0.001，R ²大于0.98的相关性被视为）。Stx1的检出限为30 ng / mL，Stx2的检出限为10 ng / mL。与乳胶纳米颗粒偶联的scFvStx1和scFvStx2提供了具有竞争性Stx检测极限的毒素检测方法，该方法成本低廉且执行时间短。此处提出的诊断方法首次使用重组抗体片段，这提出了开发更实惠的检测方法以用于STEC感染的常规检测和监视的可能性。