ANTITUBERCULOSIS ACTIVITY OF CLARITHROMYCIN

Antituberculosis activity of clarithromycin (CLA), a macrolide antibio tic, was investigated in vitro, in macrophages, and in C57BL/6 mice. C LA showed high in vitro MICs (4 to > 16 mu g/ml) for several strains o f Mycobacterium tuberculosis and caused slight enhancement of activity of rifampin (RIF) against H37Rv but failed to increase the activity o f either RIF or isoniazid (INH) against other strains, However, inside J774A.1 macrophages, CLA showed high activity and was synergistic wit h RIF against some strains of tubercle bacilli susceptible or resistan t to INH and RIF. In the in vivo studies with a drug-susceptible strai n (H37Rv), CLA protected mice from mortality due to tuberculosis for u p to 8 weeks of observation, The CFU data for lungs and Spleens reveal ed that the antituberculosis activity of CLA is inferior to those of I NH and streptomycin, However, the activity of CLA when used alone or i n combination was comparable to that of thiacetazone, indicating its p otential usefulness as a secondary drug for the treatment of tuberculo sis.