Which subtype of E.coli is associated with hemorrhagic colitis?

The subtype of E. coli associated with hemorrhagic colitis is specifically enterohemorrhagic E. coli (EHEC), predominantly serotype O157:H7. This strain produces Shiga toxin, which can disrupt the lining of the intestinal tract, leading to severe gastrointestinal symptoms such as bloody diarrhea and abdominal cramps. The production of this toxin is a critical factor in the pathogenesis of hemorrhagic colitis, as it damages the intestinal cells and triggers inflammation, contributing to the clinical presentation of the disease.

In contrast, other subtypes like enteropathogenic, enteroinvasive, and enterotoxigenic E. coli have distinct mechanisms and clinical manifestations. Enteropathogenic E. coli primarily causes diarrhea in infants through adherence to intestinal mucosa without producing significant toxins. Enteroinvasive E. coli invades the intestinal epithelium and can cause an inflammatory response similar to dysentery. Enterotoxigenic E. coli, on the other hand, is known for its ability to produce enterotoxins which lead to profuse watery diarrhea, commonly seen in travelers' diarrhea.

Understandably, while all these subtypes can lead to gastrointestinal illness, enterohemorrhagic E. coli's unique ability to