[Relationships between "Mycobacterium simiae" and the "M. avium-intracellulare-scrofulaceum" complex (author's...

The 24 strains of Mycobacterium simiae described in this report were isolated from 12 black Africans, 6 from white Europeans, 5 from primates and 1 from a leprosy infected Armadillo. These strains form 3 groups having the similar morphologic and cultural properties as M. intracellulare. Two groups were similar with respect to pigmentation, urease activity and niacin production but differed serologically, the second group being of M. intracellulare serotype 18. The third group was less homogenous and was intermediate to M. simiae and M. intracellulare. Thus M. simiae belong to the M. avium-intracellulare-simiae-scrofulaceum (MAISS) complex. Two cases of well characterized pulmonary disease progressed like M. avium mycobacteriosis.