CD4 and infection: Nontuberculous mycobacteria varying in pathogenicity are rather ubiquitous in the natural environment,[7] and MAC from water, soil, and food can cause infections in immunocompromised hosts through inhalation and ingestion.[8] This bacterium commonly causes disseminated MAC (DMAC) infection in HIV-positive patients with CD4 lymphocyte counts <50 cells/μL.