Bias of culture techniques for diagnosing mixed Mycobacterium genavense and Mycobacterium avium infection in AIDS.

Disseminated Mycobacterium avium infection is a common complication in late-stage AIDS. We describe a patient seropositive for human immunodeficiency virus with a disseminated infection caused by mycobacteria. Acid-fast rods were visible by microscopy in stool and bone marrow and in specimens from skin, liver, spleen, lung, and lymph nodes. Using molecular biology techniques and standard culture techniques, we found evidence of a mixed mycobacterial infection with M. genavense and M. avium. We suggest that the prevalence of M. genavense infection in patients with AIDS is underestimated because of the bias toward M. avium when using standard techniques for the detection and identification of mycobacteria.