Which bacteria is commonly associated with antibiotic-associated diarrhea?

Clostridium difficile is the bacteria most commonly associated with antibiotic-associated diarrhea. This occurs because the use of antibiotics can disrupt the normal gut flora, allowing C. difficile, which is part of the normal intestinal microbiota in some individuals, to overgrow. When antibiotics kill off a significant portion of the beneficial bacteria, C. difficile can proliferate and produce toxins that damage the intestinal lining, leading to inflammation and diarrhea.

C. difficile is particularly notorious for causing pseudomembranous colitis, a severe condition characterized by severe diarrhea and abdominal pain. This condition often arises after patients have been treated with broad-spectrum antibiotics, which are more likely to disturb the balance of gut microflora.

In contrast, the other bacteria listed do not have the same association with antibiotic-associated diarrhea. Staphylococcus aureus is primarily associated with food poisoning and skin infections; Streptococcus pneumoniae is a leading cause of pneumonia, meningitis, and otitis media, and Neisseria meningitidis is predominantly known for causing meningococcal meningitis. Therefore, they do not typically contribute to the phenomenon of antibiotic-associated diarrhea.