肠道出血性大肠杆菌是一种会导致出血性腹泻和结肠炎的微生物。肠道出血性大肠杆菌的致病菌有不少，最常见的是O157:H7型大肠杆菌。大肠杆菌O104:H4型被识别为德国2011年O104:H4型大肠杆菌疫情的原因。肠道出血性大肠杆菌统称为EHEC，释放志贺氏菌毒素，可以进一步导致溶血性尿毒综合征。

Enterohemorrhagic Escherichia coli strain (EHEC) is the most common E. coli strain producing disease in U.S. The clinical presentation ranges from a mild and uncomplicated diarrhea to a hemorrhagic colitis with severe abdominal pain. Serotype O157:H7 is the most commonly isolated strain and may trigger an infectious dose with 100 bacterial cells or fewer; other strain such as 104:H4 has also caused an outbreak in Germany 2011. Infections are most common in warmer months and in children under five years of age and are usually acquired from uncooked beef and unpasteurized milk and juice. Initially a non-bloody diarrhea develops in patients after the bacterium attaches to the epithelium or the terminal ileum, cecum, and colon. The subsequent production of toxins mediates the bloody diarrhea. In children, a complication can be hemolytic uremic syndrome which then uses cytotoxins to attack the cells in the gut, so that bacteria can leak out into the blood and cause endothelial injury in locations such as the kidney by binding to globotriasylceramide (Gb3).