Morphological manifestations of the atypical mycobacteriosis caused by nontuberculous mycobacteria in the HIV infected patients.

Infection with atypical mycobacteria (MAC) is a well-known complication of AIDS that typically occurs only in people with advanced immunodeficiency. We studied tissues from 13 patients with HIV and atypical mycobacterial infection who died in St Petersburg Russia from 2009-2012. Three patterns of disease were identified that suggest effects of host resistance. The first pattern was in people paucibacillary disease. They had positive blood cultures and histologic changes consistent with mycobacterial infection, but no stainable acid fast bacilli (AFB). The second group had disseminated infection in many organs including the lungs with extensive necrosis with many AFB. Finally, the third group had massive infection of many organs, but not the lungs, and only minimal necrosis. These observations suggest significant heterogeneity in atypical mycobacterial infections.