Pseudomembranous colitis is most commonly associated with what organism?

Pseudomembranous colitis is primarily caused by Clostridium difficile, often following antibiotic therapy that disrupts the normal gut flora. This bacterium produces toxins that lead to inflammation and the formation of pseudomembranes in the colon, causing symptoms such as severe diarrhea, abdominal pain, and fever.

Clostridium difficile is a spore-forming, gram-positive anaerobe that can overgrow in the gut when the protective microbial communities are diminished. The disease is particularly prominent in hospital settings where antibiotics are frequently prescribed, as well as among individuals with weakened immune systems or underlying health issues.

In contrast, the other organisms listed do not have the same association with pseudomembranous colitis. Escherichia coli may cause different types of gastrointestinal distress, but it is not linked to the specific pathophysiology of pseudomembranous colitis. Staphylococcus aureus and Bacteroides fragilis also do not play a significant role in this condition. While these bacteria can contribute to other infections, their relationship to pseudomembranous colitis is not relevant in this context.