IN-VITRO AND IN-VIVO ACTIVITIES OF CLARITHROMYCIN AGAINST THE MYCOBACTERIUM-AVIUM COMPLEX

Clarithromycin (CAM) was assessed for in vitro antimicrobial activity against various mycobacterial species. Except for Mycobacterium tuberc ulosis, CAM displayed MICs for test mycobacteria comparable to those o f sparfloxacin (SPFX) but lower than those of rifampicin (RMP) and ofl oxacin (OFLX). CAM at 0.25 mug/ml (1 MIC) exhibited bactericidal actio n against M. intracellulare growing in 7H9 medium and at 1 or 10 mug/m l (4 and 40 MIC, respectively) CAM displayed antimicrobial activity ag ainst the organism phagocytosed in murine macrophages, while RMP faile d to manifest such an effect. When CAM was given s.c. or by gavage to mice infected i.v. with M. intracellulare at doses of 0.2 to 2 mg/mous e once daily, six times per week, it exhibited significant therapeutic efficacy in terms of decreased incidence of gross lung lesions and re duced bacterial loads in the lungs and spleen.