About Nontuberculous Mycobacteria (NTM)

What is nontuberculous mycobacteria?
What is the difference between tuberculosis (TB) and NTM?
What are the different types of NTM?
What are the symptoms of an NTM Infection?
Support Groups and Additional Resources

What is nontuberculous mycobacteria?

Germs, like plants and animals, have been classified into similar groups. The groups are called "families." One such family of germs is known as the Mycobacteriaceae. Within this family there are a number of species. Some species can cause human diseases (pathogenic). Others species do not cause human diseases (saprophytic).

For example, Mycobacterium tuberculosis is an infamous species. This is the organism that causes human tuberculosis. Mycobacterium leprae is the organism that causes leprosy.

What is the difference between tuberculosis (TB) and NTM?

The Nontuberculous mycobacteria (NTM) refers to all the species in the family of mycobacteria that may cause human disease, but do not cause tuberculosis (TB). Every year in the United States approximately two people per 100,000 population develop infections caused by these lesser-known "cousins" of TB and leprosy. In fact, for unknown reasons, data suggest that there may be rising numbers of cases in certain parts of the country. The most common NTM's that require treatment are M. avium complex, M. kansasii, M. absussus, M. chelonae, M. fortuitum, M. terrae, M. xenopi, and M. simiae.

Unlike TB, which is spread from person to person, NTM infections are not considered contagious. There is no evidence that the infection can be transmitted from one person to another. Just how and why people become infected with NTM is not clear. Although the germs are found easily in water and soil, they do not affect most people. Doctors believe that some people who become infected have an unknown defect in their lung structure or function or in their immune systems. People who have damaged lung tissue from diseases such as emphysema, bronchiectasis or previous TB infection appear to be at greater risk for developing a NTM infection. People who are immunocompromised such as those who receive strong immunosuppressant medications such as prednisone, remicaid, etc. have a greater risk of developing a NTM infection that affects all organs of the body, not only the lungs. Patients with AIDS may also develop NTM infections.

What are the different types of NTM?

Under the microscope, NTM and TB appear quite similar. Careful lab studies must be performed to tell them apart. Most labs are capable of carrying the testing process far enough to determine whether they are dealing with an NTM. Fewer labs are equipped to determine exactly which organism it might be and what its susceptibility is to drugs.

The importance of identifying the exact organism can be illustrated with two of the organisms, Mycobacterium gordonae and Mycobacterium scrofulaceum. These two are very similar and react the same way in many lab tests. However, they react in different ways in the human body. One organism causes disease, the other organism does not cause disease. In this case, if the organism turns out to be M. gordonae, treatment is seldom indicated. M. gordonae is often a lab contaminant and not a cause of human disease. In fact, M. gordonae is found in water supplies so often that it is nicknamed “the tap water bacillus”. M. scrofulaceum, on the other hand, is known to cause disease and may require specific forms of treatment.

What are the symptoms of an NTM Infection?

Like TB, an NTM infection affects the lungs so the symptoms are similar. Most NTM infections and resulting symptoms progress slowly. Symptoms may include:

• Fever
• Weight loss
• Cough
• Lack of appetite
• Night sweats
• Blood in the sputum (phlegm)
• Loss of energy

Interested in finding out about support groups and additional resouces?

This information has been approved by Gwen Huitt M.D.,  (April 2006).