e coli definition
Definition. Escherichia coli (E. coli) bacteria normally live in the intestines of healthy people and animals. Most varieties of E. coli are harmless or cause relatively brief diarrhea. But a few particularly nasty strains, such as E. coli O157:H7, can cause severe abdominal cramps, bloody diarrhea and vomiting.You may be exposed to E. coli from contaminated water or food â especially raw vegetables and undercooked ground beef.ost varieties of E. coli are harmless or cause relatively brief diarrhea. But a few particularly nasty strains, such as E. coli O157:H7, can cause severe abdominal cramps, bloody diarrhea and vomiting. You may be exposed to E. coli from contaminated water or food â especially raw vegetables and undercooked ground beef.