Mycobacterium avium is a ubiquitous organism found in soil and water. It is mostly pathogenic to people who are immunocompromised, especially those with AIDS. M. avium can be isolated from blood, urine, and stool cultures of an AIDS patient and subsequently cultured on Middlebrook 7H11, a medium designed to propagate the growth of mycobacteria. The colony morphology of M. avium can be seen on Middlebrook 7H11 after 10 days of incubation. The colonies appear a tan color with irregular margins. M. avium has been known to have a variety of colony types, including smooth opaque, smooth transparent, and rough. It is important to adequately identify and treat M. avium because it can be a fatal pathogen to those who are immunocompromised.
The image shows the colony morphology of a patient specimen on Middlebrook 7H11 after 10 days of incubation.
Legend written by: Lindsay Sweet
Colorado State University
Fort Collins, Colorado 80523