Bacteremic
infection caused by organisms of the Mycobacterium avium complex (MAC) is common in patients with
AIDS. We evaluated both
clarithromycin and
dapsone alone and in combination for the treatment and prevention of disseminated MAC disease in beige mice. In the therapeutic model, C57BL/6 beige mice were infected intravenously with strain 101 of MAC (serovar 1). After 1 week postinfection, mice were given
clarithromycin (200 mg/kg of
body weight per day) and
dapsone (15 mg/kg of
body weight per day) alone or in combination by gavage. Treatment with
clarithromycin resulted in a significant reduction in
bacteremia and the numbers of CFU of MAC in the liver and spleen. Treatment with
dapsone had no effect on the mycobacterial counts in blood, liver, or spleen, and the combination of
dapsone with
clarithromycin was no better than
clarithromycin as a single agent.
Clarithromycin and
dapsone were used to prevent systemic disease in beige mice infected orally with MAC 101.
Clarithromycin prophylaxis was associated with a significant reduction in the numbers of bacteria in the liver, spleen, and appendix compared with those in controls. Prophylaxis with
dapsone resulted in a mild reduction in the numbers of MAC in the spleen but not in the other tissues.
Clarithromycin both treats and prevents MAC disease in beige mice.
Dapsone has no
therapeutic effect, but it does have a slight prophylactic effect, and in combination with
clarithromycin it does not abrogate the effect of
clarithromycin.