Disseminated Mycobacterium avium complex (DMAC) in an immunocompetent adult [Case Study]

A female patient with multiple osteomyelitis and pulmonary Mycobacterium avium disease visited an orthopaedic clinic with back pain. Systemic bone scan showed multiple sites of increased radioactivity in the vertebral bodies, right scapula, femurs and ribs. M. avium was isolated from sputum and a sample aspirated from the right scapula. The route of infection was unknown as there was no history of trauma or surgery. HIV testing was negative. As there was no underlying immunological disease she was diagnosed as disseminated M. avium complex (DMAC) disease in an immunocompetent adult. Cytokine production on several stimuli from peripheral blood mononuclear cells was similar to that in pulmonary M. avium patients. Sequence analysis of IFN-γ receptor revealed no nucleotide substitution. We detected serotypes 1, 2 and 4 from mycobacteria cultured from the right scapula, and conclude that this case could be the result of undetected immune deficiency and/or unrecognised virulence of the infecting isolate.