To determine the antimicrobial activity and tolerability of rifapentine alone and in combination therapy in patients with AIDS and disseminated Mycobacterium avium complex (MAC) bacteremia. To determine the pharmacokinetics of rifapentine and its metabolite, 25-desacetyl, alone and in combination therapy. To determine the pharmacokinetics of azithromycin and clarithromycin (and its 14-OH metabolite) in combination therapy.