Mycobacterium leprae
Fusidic acid is active "in vitro" against "Staphylococcus aureus", most coagulase-positive staphylococci, Beta-hemolytic streptococci, "Corynebacterium" species, and most clostridium species. Fusidic acid has no known useful activity against enterococci or most Gram-negative bacteria (except Neisseria, Moraxella, "Legionella pneumophila", and "Bacteroides fragilis"). Fusidic acid is active "in vitro" and clinically against "Mycobacterium leprae" but has only marginal activity against "Mycobacterium tuberculosis".