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Case 4: A 32-Year-Old with Fever, Weight Loss, and Fatigue

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D The preferred therapy for disseminated MAC consists of clarithromycin (Biaxin), rifabutin (Mycobutin), and clofazimine (Lamprene). Recent studies have shown that clofazimine decreases the MAC relapse rate more than ethambutol (Myambutol) and thus it has replaced the ethambutol in the preferred MAC treatment regimen.

This answer is incorrect. Most experts would recommend a regimen of clarithromycin plus ethambutol (Myambutol), with or without rifabutin, for the treatment of disseminated MAC. Ethambutol significantly decreases MAC relapse rates. The use of clofazimine does not improve bacteriologic responses or decrease MAC relapse rates; indeed, it has been associated with increased mortality and should not be used to treat MAC. The data regarding the benefit of rifabutin are conflicting.

A The anemia would be unusual with MAC and would strongly suggest a diagnosis other than MAC.
B Among patients with disseminated MAC, fewer than 45% will have blood cultures that turn positive within 21 days. Thus, if MAC is suspected, the patient should proceed to bone marrow aspirate and culture to improve the diagnostic yield.
C The 2002 U.S. Public Health Service 2002 Guidelines for Preventing Opportunistic Infections state that secondary prophylaxis (to prevent recurrence of disseminated MAC) may be discontinued in patients treated with HAART who have a sustained (greater than 6 months) increase in CD4 count to greater than 100 cells/mm3 if they have completed 12 months of MAC therapy and have no ongoing symptoms or signs attributable to MAC.

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