Escherichia coli (E. coli) is a bacteria species that normally lives in the intestines of healthy people and animals. More than 700 serotypes of E. coli have been identified. Most varieties of E. coli are harmless or cause relatively brief diarrhea, but a few strains can cause severe abdominal cramps, bloody diarrhea and vomiting.

E coli 0157 is a pathogen causing hemorrhagic diarrhea, and to kidney failure.