Which strain of E. coli is most commonly associated with bloody diarrhea?

EHEC O157:H7 is the strain of Escherichia coli most commonly associated with bloody diarrhea. This particular strain is known for producing a potent Shiga toxin that damages the intestinal lining, leading to severe inflammation and ulceration. The result of this damage is often bloody diarrhea, which can also be accompanied by abdominal cramps and, in severe cases, hemolytic uremic syndrome (HUS), a serious complication characterized by kidney failure.

Contrastingly, the other strains listed have different associations. Enterotoxigenic E. coli (ETEC) typically causes a watery diarrhea, mainly through the secretion of heat-labile and heat-stable enterotoxins, and is commonly linked to traveler’s diarrhea rather than blood-stained stools. Enteroinvasive E. coli (EIEC) can mimic the symptoms of shigellosis, presenting with diarrhea that may be bloody, but it is less common than EHEC. Enteroaggregative E. coli (EAEC) is primarily associated with persistent diarrhea, particularly in young children, and does not typically result in bloody diarrhea.

The specific mechanisms by which EHEC O157:H7 induces bloody diarrhea, coupled with its association with outbreaks (especially from under