WBR0889

Author	[[PageAuthor::Ayokunle Olubaniyi, M.B,B.S [1]]]
Exam Type	USMLE Step 3
Main Category	Community Medical Health Center
Sub Category	Infectious Disease
Prompt	A 65-year old man comes to the outpatient gastroenterology clinic for a routine check-up. He was admitted and treated 2 months ago for community acquired pneumonia. He has no complaint today and his vitals are within normal limit. His laboratory investigations are also normal except for a positive Clostridium difficile toxin assay. What is the best next step to take in the management of this patient?
Answer A	Observe and counsel
Answer A Explanation	No treatment is indicated for patients who have a positive C. diff toxin assay without symptoms.
Answer B	Administer oral metronidazole as prophylaxis for the next 7 days
Answer B Explanation	Oral metronidazole is indicated as an initial treatment of a mild form of C. diff infection. It is usually administered for 10-14 days.
Answer C	Administer oral vancomycin as prophylaxis for the next 2 weeks
Answer C Explanation	This is reserved for severe cases, and also for those who experienced a relapse after a course of metronidazole treatment. The use of vancomycin is limited due its expensive cost, and also the risk of developing vancomycin-resistant enterococci (VRE).
Answer D	Schedule colonoscopy immediately
Answer D Explanation	This is reserved for cases with a high suspicion of C. diff infection despite negative laboratory assay, failure of response to drug treatment or in cases where prompt diagnosis is required. This reveals the presence of a pseudomembrane in the colon.
Answer E	Order an abdominal CT
Answer E Explanation	This demonstrates a pronounced thickening of the colonic wall in patients with pseudomembranous colitis.
Right Answer	A
Explanation	Clostridium difficile is an organism normally seen in the intestine. However, it may overgrow when you take antibiotics which kill a lot of gut flora which impede their growth in the intestine. The bacteria release a powerful toxin that causes the lining of the colon to become inflamed and bleed. The symptoms experienced during an acute infection are offensive-smelling watery diarrhea, fever, and abdominal pain. Toxic megacolon may result in severe cases which involves surgery. A positive Clostridium difficile toxin assay may signify an acute infection or a recent infection. However, treatment is not indicated for an asymptomatic patient with a positive assay. Educational Objective: No treatment is indicated for patients who have a positive C. diff toxin assay without symptoms. Educational Objective: References:
Approved	No
Keyword	Pseudomembranous colitis
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