CLARITHROMYCIN, DAPSONE, AND A COMBINATION OF BOTH USED TO TREAT OR PREVENT DISSEMINATED MYCOBACTERIUM-AVIUM INFECTION IN BEIGE MICE

Bacteremic infection caused by organisms of the Mycobacterium avium co mplex (MAC) is common in patients with AIDS. We evaluated both clarith romycin and dapsone alone and in combination for the treatment and pre vention 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 clarit hromycin (200 mg/kg of body weight per day) and dapsone (15 mg/kg of b ody weight per day) alone or in combination by Savage. Treatment with clarithromycin resulted in a significant reduction in bacteremia and t he numbers of CFU of MAC in the liver and spleen. Treatment with dapso ne had no effect on the mycobacterial counts in blood, liver, or splee n, and the combination of dapsone with clarithromycin was no better th an clarithromycin as a single agent. Clarithromycin and dapsone were u sed to prevent systemic disease in beige mice infected orally with MAC 101. Clarithromycin prophylaxis was associated with a significant red uction in the numbers of bacteria in the liver, spleen, and appendix c ompared with those in controls. Prophylaxis with dapsone resulted in a mild reduction in the numbers of MAC in the spleen but not in the oth er tissues. Clarithromycin both treats and prevents MAC disease in bei ge mice. Dapsone has no therapeutic effect, but it does have a slight prophylactic effect, and in combination with clarithromycin it does no t abrogate the effect of clarithromycin.