Mycobacterial Infections, Atypical

Atypical mycobacterial (my-ko-bak-TEER-e-ul) infections are infections caused by mycobacteria * other than those that cause tuberculosis * .

What Are Atypical Mycobacterial Infections?

Atypical mycobacteria are commonly found in the environment, such as in soil and water, and in food. Most of the time they do not cause infection or illness in healthy people. When a person's immune system is weakened, however, as occurs in people who have HIV * or AIDS * , several strains of mycobacteria can cause opportunistic infections * . Atypical mycobacteria are related to the bacterium that causes tuberculosis (TB), but they often are resistant to the drugs used to treat TB. These strains are called “mycobacteria other than tuberculosis,” or MOTT. Sometimes, they are also called “nontuberculous mycobacteria,” or NTM.

Although some mycobacteria can live on human skin or in the nose, atypical mycobacterial infections are not known to spread from person to person. Rather, infection comes from direct contact with the bacteria in the environment.

Are Atypical Mycobacterial Infections Common?

Mycobacterial infections other than tuberculosis are uncommon. Most frequently, they affect people with HIV or AIDS. As cases of HIV and AIDS increased from the 1980s into the early 2000s, so did instances of Mycobacterium infections, and in the United States, these infections were more common than tuberculosis. People with seriously weakened immune systems or chronic lung disease are at greatest risk.

How Do People Know They Have an Atypical Mycobacterial Infection?

Signs and symptoms of atypical mycobacterial infections include fever, swollen lymph nodes, extreme tiredness, night sweats, weight loss, diarrhea (di-a-RE-a), joint and bone pain, cough, shortness of breath, skin lesions * , general discomfort, and paleness. Many of these symptoms can be signs of less serious conditions, but in a person with a weakened immune system, a combination of such symptoms suggests a MOTT infection. In children, lymphadenitis * is the most common type of MOTT infection, whereas lung infections, which occur less often in children, are the most common in adults.

What Are Some Specific Infections?

Mycobacterium avium complex (MAC) * , and intestines in people with HIV. MAC infection in an HIV-positive person can signal the start of full-blown AIDS. Such a so-called disseminated * disease rarely occurs in people with healthy immune systems.

Mycobacterium marinum

This infection causes skin lesions, sometimes known as swimming pool granuloma * or fish tank granuloma. Infection with M. marinum (MAR-ih-num) is very rare, occurring in less than 1 in 100,000 people. Most at risk are people with weakened immune systems and people who handle fish, are exposed to contaminated water in aquariums, or swim in fresh or salt water that contains the mycobacterium. Several weeks after a person has contact with contaminated water, a bump appears on a hand, arm, or foot where there was a break in the skin. The lesion grows and drains over several weeks, leaving an ulcer * . Occasionally, a deep infection will cause tenderness and swelling in the nearby bone or joints.

Mycobacterium ulcerans

Infection with M. ulcerans (UL-sir-ans) occurs in tropical and subtropical regions in Asia, the western Pacific, and Latin America, but it is most common in West Africa. The infection causes skin lesions known as Buruli (boo-REH-lee) ulcers, named for a region in Uganda in Africa. The ulcers develop mainly on the limbs, grow slowly, and release a toxin (or poison) that damages the skin and underlying tissue. The infection is relatively painless, but if left untreated, it can destroy massive amounts of skin and bone, leading to permanent deformities.

Mycobacterium kansasii

Infection with M. kansasii (kan-ZAS-e-eye) causes a lung disease similar to tuberculosis, although not as severe. Patients may experience fever and cough, and a doctor often hears wheezing and “crackling” when listening to the patient's lungs. This infection can also involve the lymph nodes and cause skin lesions. In people with weak immune systems, the infection can erupt into widespread disease. This infection is rare in the United States, but people with chronic lung disease are especially susceptible. If left untreated, the disease frequently worsens and can be fatal.

How Do Doctors Diagnose and Treat Atypical Mycobacterial Infections?

A doctor can perform several tests to detect mycobacteria, including examination and culture * of samples of blood, sputum * , bowel movement, or bone marrow. Chest x-rays or computed tomography * (CT) scans can show disease in the lungs. Some cases may require endoscopy * to collect a sample of lung or stomach tissue or biopsies * of skin or lymph node tissue. A quick diagnosis of mycobacterial infections is crucial, as treatment must begin as soon as possible.

Lady Windermere Syndrome

Lady Windermere syndrome is a particular kind of atypical mycobacterial condition that causes chronic cough, fatigue, weight loss, and other less specific symptoms. It particularly affects older women who do not have an immune disorder or other lung disease. The syndrome is named for a character in Oscar Wilde's 1892 play Lady Windermere's Fan. In the play, Lady Windermere is a very fussy young woman who maintains her composure to the point of refusing to cough in public.

When the syndrome was named in 1992, it was proposed that this suppression of coughing may lead to an inflammation in part of the lungs, and this in turn makes the lungs more prone to a mycobacterial infection.

A doctor may also order a PPD (purified protein derivative) skin test for TB. Because atypical mycobacteria are so similar to the bacterium that causes TB, this test will often be positive in patients with an atypical mycobacterial infection, although not as strongly positive as it would be in patients with TB.

Treatment for mycobacterial infections depends on the type of bacterium, the location and severity of the infection, and the status of the person's immune system. Resistant and severe infections usually require treatment with a combination of antibiotics, and doctors may prescribe up to six medications to use at once. Surgery, sometimes along with medications, is the most effective way to treat lymph node infections and skin lesions.

Treatment for MOTT infections can take six months to two years. Antibiotics work during the growth stage of bacteria, and mycobacteria are slow-growing. If left untreated, MOTT infections can spread throughout the body, especially in people with weak immune systems. They can cause abscesses * , bone and joint infections, and infections of the lymph nodes, lungs, or soft tissue. Widespread infections can lead to serious illness and even death.

Can People Prevent Atypical Mycobacterial Infections?

Because mycobacteria are common in the environment, these infections are difficult to prevent, especially in people with weakened immune systems. Doctors may prescribe preventive medications for people who are at risk, such as those with HIV or AIDS. Getting enough sleep and eating a healthy diet can also help these patients cope with and fight these infections.

See also AIDS and HIV Infection • Bacterial Infections • Tuberculosis


Books and Articles

Dieudonne, Arry. “Atypical Mycobacterial Infection.” Medscape, January 7, 2015. (accessed October 28, 2015).

Schlossberg, David. Tuberculosis and Nontuberculosis Mycobacterial Infections, Sixth Edition. Washington, DC: ASM Press, 2011.

Wentworth, Ashley B., “Increased Incidence of Cutaneous Nontuberculosis Mycobacterial Infection, 1980 to 2009: A Population-Based Study.” Mayo Clinic Proceedings 88, 1 (January 2013): 38–45. (accessed November 21, 2015).


American Lung Association. “Nontuberculous Mycobacterium.” (accessed October 28, 2015).

MedlinePlus. “Mycobacterial Infections.” U.S. National Library of Medicine, National Institutes of Health. (accessed October 28, 2015).

Merck Manual: Consumer Version. “Infections That Resemble Tuberculosis (TB) (Other Mycobacterial Infections).” (accessed November 21, 2015).

National Organization for Rare Disorders. “Nontuberculous Mycobacterial Lung Disease.” (accessed November 21, 2015).

Ngan, Vanessa. “Atypical Mycobacterial Infection.” DermNet NZ. (accessed November 21, 2015).


American Lung Association. 55 West Wacker Dr., Suite 1150, Chicago, IL 60601. Toll-free: 800-586-4872. Website: (accessed October 28, 2015).

Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30329. Toll-free: 800-311-3435. Website: (accessed October 28, 2015).

National Organization for Rare Disorders. 55 Kenosia Ave., PO Box 1968, Danbury, CT 06813. Telephone: 203-744-0100. Website: (accessed November 13, 2015).

NTM Info & Research, Inc. 1550 Madruga Ave., Suite 230, Coral Gables, FL 33146. Telephone: 305-667-6461. Website: (accessed November 21, 2015).

* mycobacteria (my-ko-bakTEER-e-uh) belong to a family of bacteria called fungus bacteria because they are found in wet environments.

* tuberculosis (too-ber-kyoo-LOsis) is a bacterial infection that primarily attacks the lungs but can spread to other parts of the body.

* HIV or human immunodeficiency virus (HYOO-mun ih-myoono-dih-FIH-shen-see) is the virus that causes AIDS (Acquired Immunodeficiency Syndrome), an infection that severely weakens the immune system.

* AIDS (or Acquired Immunodeficiency [ih-myoo-no-dihFIH-shen-see] Syndrome) is an infection that severely weakens the immune system; it is caused by the human immunodeficiency virus (HIV).

* opportunistic infections are infections caused by infectious agents that usually do not produce disease in people with healthy immune systems but can cause widespread and severe illness in patients with weak or faulty immune systems.

* lesions (LEE-zhuns) is a general term referring to sore or damaged or irregular areas of tissue.

* lymphadenitis (lim-fah-den-EYEtis) is inflammation of the lymph nodes and channels of the lymphatic system.

* bone marrow is the soft tissue inside bones where blood cells are made.

* disseminated describes a disease that has spread widely in the body.

* granuloma (gran-yoo-LO-muh) is chronically inflamed and swollen tissue that often develops as the result of an infection.

* ulcer is an open sore on the skin or the lining of a hollow body organ, such as the stomach or intestine. It may or may not be painful.

* culture (KUL-chur) is a test in which a sample of fluid or tissue from the body is placed in a dish containing material that supports the growth of certain organisms. Typically, within days the organisms will grow and can be identified.

* sputum (SPYOO-tum) is a substance that contains mucus and other matter coughed out from the lungs, bronchi, and trachea.

* computed tomography (kom-PYOO-ted toe-MAH-gruh-fee), or CT, also called computerized axial tomography (CAT), is a technique in which a machine takes many x-rays of the body to create a three-dimensional picture.

* endoscopy (en-DOS-ko-pee) is a type of diagnostic test in which a lighted tube-like instrument is inserted into a part of the body.

* biopsies (BI-op-seez) are tests in which small samples of skin or other body tissue are removed and examined for signs of disease.

* abscesses (AB-seh-sez) are localized or walled off accumulations of pus caused by infection that can occur anywhere in the body.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)