Case 3: Prophylaxis for Mycobacterium avium complex

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You answered:

	The patient's CD4 count is less than 50 cells/mm³ so he should immediately start clarithromycin (Biaxin) plus rifabutin (Mycobutin) for prophylaxis against disseminated MAC.

This answer is incorrect. The patient's constitutional symptoms raise concerns about the possibility of disseminated MAC infection and disseminated MAC should be ruled out prior to starting prophylaxis. If the patient had disseminated MAC, the use of a single drug for prophylaxis could result in drug-resistant MAC. Available data suggest that rifabutin plus clarithromycin is no more effective than clarithromycin (Biaxin) alone for MAC prophylaxis and the combination is associated with a higher rate of adverse reactions. In addition, rifabutin could potentially cause significant drug-drug interactions in this patient.

Choose another answer:

	The patient's CD4 count is less than 50 cells/mm³ and this warrants monthly sputum and stool surveillance cultures for MAC infection. Prophylaxis against disseminated MAC should occur only if the patient has a stool or urine culture positive for MAC.
	Recent guidelines recommend initiating prophylaxis against disseminated MAC in a patient with a CD4 cell count less than 100 cells/mm³ if they have concomitant oral candidiasis.
	The patient's symptoms of weight loss and night sweats suggest he may possibly have disseminated MAC. Before prophylaxis against disseminated MAC is started, disseminated MAC infection should be ruled out.

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