From DrugPedia: A Wikipedia for Drug discovery
M. leprae is an aerobic rod-shaped (bacillus) surrounded by the characteristic waxy coating unique to mycobacteria. In size and shape, it closely resembles Mycobacterium tuberculosis. Due to its thick waxy coating, M. leprae stains with a carbol fuscin rather than with the traditional Gram stain. The culture takes several weeks to mature.
 Surface Characteristics
Mycobacterial lipoarabinomannan is a phosphatidylinositol anchored lipoglycan that consists of an α1-->6 linked backbone, substituted to varying degrees at position 2 with single α-Man residues and directly attached to position 6 of the myo-inositol of a phosphatidylinositol (PI) anchor
 Pathogenic Activity
It is a bacterium that causes leprosy (Hansen's disease).
Virulence factors include a waxy exterior coating, formed by the production of mycolic acids unique to Mycobacterium.