Pseudomembranous colitis is caused by?

ANSWER: (B) Clostridium difficilleREF: Jawetz microbiology 24th ed chapter 12"Clostridia cause several important toxin-mediated diseases: Clostridium tetani, tetanus; Clostridium botulinum, botulism; Clostridium perfringens, gas gangrene; and Clostridium difficile, pseudomembraneous colitis"PSEUDOMEMBRANOUS COLITISPseudomembranous colitis, a cause of antibiotic-associated diarrhea (AAD), is an infection of the colon. It is often, but not always, caused by the bacterium Clostridium difficile. The illness is characterized by offensivesmelling diarrhea, fever, and abdominal pain. In severe cases, life-threatening complications can develop, such as toxic megacolon.Pseudomembranous colitis is due infection by Clostridium difficleA gram-positive anaerobic bacillusNot identified until 1953 because it was 'difficult' to cultureBroad-spectrum antibiotics are main culpritsAlthough many antibiotics have been associated with pseudomembraneous colitis, the most common are ampicillin and clindamycin.Allows colonisation by C. difficle transmitted by the faecal-oral routeExotoxins (Toxin A & B) produced by bacteria. Toxin A is a potent enterotoxin while Toxin B is a potent cytotoxin,Pseudomembraneous colitis is diagnosed by detection of one or both C difficile toxins in stool and by endoscopic observation of pseudomembraneous or microabscesses in patients who have diarrhea and have been given antibiotics.Produces mucosal inflammation and cell damageIf severe epithelial necrosis a pseudo-membrane is formedConsists of mucin, fibrin, leucocytes and cellular debrisThe disease is treated by discontinuing administration of the offending antibiotic and orally giving either metronidazole or vancomycin.ANTIBIOTIC-ASSOCIATED DIARRHEA:The administration of antibiotics frequently leads to a mild to moderate form of diarrhea, termed antibiotic- associated diarrhea. This disease is generally less severe than the classic form of pseudomembraneouscolitis. As many as 25% of cases of antibiotic-associated diarrhea may be associated with C difficile.