Although many types of Escherichia coli (E coli) bacteria live normally in the intestinal tract, at least 5 types are known to cause diarrhea. Shiga toxin–producing E coli has caused numerous outbreaks in group care settings. Infections with Shiga toxin–producing E coli may be associated with other severe problems, such as bleeding from irritation of the bowel, kidney damage, and blood cell damage, also known as hemolytic uremic syndrome. Other diarrhea-producing types are enteropathogenic E coli, enteroinvasive E coli, enteroaggregative E coli, and in children and families who travel, enterotoxigenic E coli.