Disseminated Mycobacterium simiae infection in patients with AIDS

Abstract

Objectives: To report our experience with disseminated Mycobacterium simiae disease in patients with AIDS, and review other cases reported in the literature.

Methods: We retrospectively reviewed all cases of M. simiae that were isolated from sterile body sites over a 9-year period at the University Health System Hospital at San Antonio, Texas, U.S.A. Data included patient demographics, clinical features, other accompanying opportunistic infections, in vitro susceptibility, therapy and outcome.

Results: Ten cases of M. simiae disseminated disease were identified. All of them were inpatients with AIDS. Another nine cases of disseminated infection in AIDS patients were reported in the literature. Advanced AIDS with absolute CD4 counts of less than 50 and an associated AIDS-defining illness characterized all cases. Persistent fever and debilitation without localizing signs were the most common clinical features. Our patients responded poorly to antimycobacterial drugs and died within 6 months of diagnosis. The only reported successful therapy was in patients who responded well to highly active antiretroviral therapy and antimycobacterial regimens containing clarithromycin, ethambutol and ciprofloxacin.

Conclusions: Clinical presentation of M. simiae infection mimics Mycobacterium avium complex, with fever and progressive debilitation, but is less responsive to therapy. Immuno-reconstitution with potent antiretroviral therapy may be the best therapy for such resistant disease.