Mycobacteria other than tuberculosis and leprosy cause disorders primarily seen in tropical countries. As opposed to Mycobacterium tuberculosis and M leprae, they are usually environmental saprophytes, not obligate human/animal pathogens. Human exposure may be via inhalation, contaminated water, or preexisting wound contamination. Overall, nontuberculosis mycobacteria can cause four different clinical syndromes: pulmonary disease, regional lymphadenitis, disseminated disease in immunocompromised patients, and skin/soft-tissue infections.
Buruli ulcer is the most important disorder caused by infection with Mycobacterium ulcerans. They are seen throughout the tropics but are particularly prevalent in Africa. The ulcer is slow growing with extensive necrosis and deep undermining of wound edges. Serious complications can occur, including osteomyelitis, contractures, and scarring.
A variety of other cutaneous forms of mycobacterial diseases exist. Fish tank granuloma (from Mycobacterium marinum) is seen following handling of tropical fish tanks and occasionally in fishermen. Posttraumatic abscesses are caused by the rapidly growing mycobacteria, Mycobacterium fortuitum and Mycobacterium chelonae.
Disseminated disease from Mycobacterium avium complex is a late-stage opportunistic infection in HIV/AIDS but is occasionally seen in immunocompetent individuals.
Management and Disposition
Providers should consider these illnesses in the differential diagnosis when patients present with typical skin lesions and in severely immunocompromised AIDS patients. Buruli ulcer is typically treated for 8 weeks with rifampin and either streptomycin or clarithromycin. Surgical excision with grafting may be needed. Other infections are treated with macrolides or other antibiotics.
Buruli ulcer is the 3rd most common mycobacterial disease worldwide, after tuberculosis and leprosy.
Consider M marinum infection in patients with a hand lesion following tropical fish tank manipulation.
Fast-growing mycobacteria such as M chelonae cause “cold abscesses,” often seen after nonsterile injections that are given for cosmetic purposes. A recent outbreak of this organism was also seen following tattooing.
Some postulate that Crohn disease and sarcoidosis may be caused by yet unidentified mycobacteria.
Mycobacterium haemophilum is considered the 2nd most common cause of cervical lymphadenitis in children.
Buruli Ulcer. Characteristic shallow base with undermined edges involving the knee. (Photo contributors: Shannon Langston, MD, and Universidad Peruana Cayetano Heredia, Lima, Peru.)
Cold Abscess. A cold abscess following a cosmetic injection for weight loss. (Photo contributors: Seth W. Wright, MD, and Universidad Peruana Cayetano Heredia, Lima, Peru.)
Cold Abscesses. A patient with multiple recurrent cold abscesses from M chelonae following nonsterile weight loss injections in Peru. (Photo contributors: Rob Greidanus, MD, and Universidad Peruana Cayetano Heredia, Lima, Peru.)