Clinical and Bacteriologic Impact of Rifabutin Prophylaxis for Mycobacterium avium Complex Infection in Patients with Human Immunodeficiency Virus Infection

We conducted a prospective observational study to determine the feasibility and impact of rifabutin prophylaxis (300 mg daily) for human immunodeficiency virus-infected patients whose CD4 cell counts were <100/mm3. Three hundred seventy-one patients (65.2% of all patients with CD4 cell counts of <100/mm3 [mean +/- SD, 30 +/- 25/mm3]) received rifabutin prophylaxis for a mean duration +/- SD of 35.5 +/- 34.2 weeks; 198 patients (mean CD4 cell count +/- SD, 51.6 +/- 32/mm3) did not receive prophylaxis. Rifabutin prophylaxis for 8.4% of patients was interrupted because of adverse events. Mycobacterium avium complex (MAC) bacteremia developed in 17 (4.6%) of 371 patients receiving rifabutin prophylaxis and in 22 (11.1%) of 198 patients not receiving rifabutin prophylaxis. The mean CD4 cell count +/- SD at the diagnosis of MAC bacteremia was lower in patients receiving prophylaxis than in those not receiving prophylaxis (11.5 +/- 6.8/mm3 vs. 34.7 +/- 36/mm3, respectively; P < .01). MICs for MAC strains isolated from patients receiving prophylaxis were less than or equal to those for strains isolated from patients not receiving prophylaxis.