Describe the pathogenesis of the atypical mycobacteria.

Atypical mycobacteria (also known as nontuberculous mycobacteria, or NTM) are ubiquitous and are found in soil, water, and domestic and wild animals. Tap water is the major reservoir for the atypical mycobacteria that cause human disease. Because they are found everywhere, isolation of these organisms does not necessarily constitute proof of disease. In contrast to M. tuberculosis, they are not transmitted from person to person. Immunosuppression, organ damage, Mohs micrographic surgery, cutaneous surgery, punch biopsy, acupuncture, mesotherapy, injections, cardiothoracic surgery, breast reconstruction, facial plastic surgery, laser resurfacing, liposuction, body piercing, pedicures, tattoos, or minor cuts and abrasions are some of the clinical settings in which these organisms can cause disease. The presentation of these infections is quite variable, leading to frequently missed diagnoses. Depending on geographic location, atypical mycobacteria may account for 0.5% to 30% of all mycobacterial infections.

Drage LA, Ecker PM, Orenstein R, et al: An outbreak of Mycobacterium chelonae infections in tattoos, J Am Acad Dermatol 62:501– 506, 2010. [Epub ahead of print.]