Low Serum Levels of Oral Antimycobacterial Agents in Patients with Disseminated Mycobacterium avium Complex Disease

Twenty-sevenhuman immunodeficiencyvirus-infected patients with disseminated Mycobacterium avium complex disease who were treated with oral antimycobacterial agents (clofazimine, ciprofioxacin, ethambutol, and rifampin) were studied to evaluate the usefulness of monitoring serum drug concentrations and testing in vitro susceptibility of M. avium complex (MAC) isolates. Twenty patients tolerated treatment with three or four antimycobacterial agents for at least 8 weeks; mycobacteremia was eradicated in 7 (35%).The in vitro susceptibilities of MAC isolates to antimycobacterial agents were similar for these 7 and for the 13 who did not respond to antimycobacterial treatment. Serum drug levels were below the expected range in 6 of the 7 whose mycobacteremia was cleared and in 9 ofthe 13 nonresponders (P = .41). These low serum concentrations of antimycobacterial drugs may be due to impaired drug absorption in patients with AIDS and disseminated MAC disease.