Atypical Mycobacteria

What are atypical mycobacteria?

Atypical mycobacteria are a group of bacteria that are widely distributed in nature. They can be found in water, soil, animals and man, usually without evidence of disease.

Are these the same organisms that cause tuberculosis?

No, the organism that causes tuberculosis is Mycobacterium tuberculosis (M. tb). The atypical mycobacteria belong to the same family of mycobacterial organisms as M.tb but include other species such as M.avium, M. intracellularae, M. kansasii, M. xenopi, and M. fortuitum.

How does an individual acquire atypical mycobacterial infection?

Most infections with these organisms are believed to arise from environmental exposure to organisms in infected water, soil, dust, or aerosols. Person-to-person and animal-to-animal transmission of atypical mycobacteria is not an important factor in acquisition of infection with these organisms.

Do these organisms cause disease?

Many people become infected with and harbor atypical mycobacteria in their respiratory secretions without any symptoms or evidence of disease. In some individuals, however, infection with these organisms may result in disease involving the lungs, skin, or lymph nodes. These organisms may also infect open wounds.

What are the signs and symptoms of atypical mycobacterial infection?

Patients with disease caused by atypical mycobacteria commonly present with respiratory symptoms, such as cough and increased sputum production, and abnormalities on the chest x-ray. Patients may also experience fever, weakness, and weight loss. An altered immune system, underlying illness or tissue damage may make a person more likely to develop disease if infected with atypical mycobacteria.

Can persons with atypical mycobacterial disease infect others?

With the exception of organisms causing skin lesion, there is no evidence of person-to-person spread of these organisms. Individuals with respiratory disease do not readily infect others and, therefore, do not need to be isolated from others.

How is disease caused by atypical mycobacteria treated?

Treatment is based on results of laboratory testing that will identify an effective antibiotic for treatment. Preventive treatment of close contacts of persons with disease caused by atypical mycobacterium is not indicated.

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.