Shiga toxin (Stx), one of the most potent bacterial toxins known, can cause bloody diarrhea, hemolytic uremic syndrome, kidney failure and death. The aim of this pilot was to investigate the occurrence of Shiga toxin-encoding genes, stx (stx1 and stx2) from total coliform (TC) and E. coli positive samples from small community water systems. After aliquots for TC and E. coli analyses were removed, the remnant volume of the samples was enriched, following a protocol developed for this study. Fifty-two per cent of the samples tested by multiplex PCR were positive for the presence of the stx genes; this percentage was higher in raw water samples. The stx2 gene was more abundant. Testing larger volumes of the samples increase the sensitivity of our assay, providing an alternative protocol for the detection of Shiga toxin-producing E. coli (STEC) that might be missed by the TC assay. This study confirms the presence of Stx encoding genes in source and distributed water for all systems sampled and suggests STEC as a potential health risk in small systems.

志贺毒素（Stx）是已知的最有效的细菌毒素之一，可引起血液性腹泻，溶血性尿毒症综合征，肾衰竭和死亡。该试验的目的是研究总菌群（TC）和小型社区供水系统中大肠杆菌阳性样本中志贺毒素编码基因stx（stx 1和stx 2）的发生。删除用于TC和大肠杆菌分析的等分试样后，按照针对本研究制定的方案，富集了样品的残留量。多重PCR检测的样品中有52％的stx基因阳性。在原水样品中该百分比更高。该志贺毒素基因更加丰富。测试更大数量的样品可以提高我们测定的灵敏度，从而为检测产生志贺毒素的大肠杆菌（STEC）提供了另一种方法，而该方法可能会被TC分析遗漏。这项研究证实了所有采样系统在水源和分布式水中均存在Stx编码基因，并暗示STEC在小型系统中具有潜在的健康风险。