Tuberculosis belongs to a group of bacteria called mycobacteria. There are many types of mycobacteria other than tuberculosis. The most common non-TB mycobacterium is referred to as MAC. MAC stands for mycobacterium avium complex. We get several cases of this in the office every year. Patients who have this infection are often elderly and have some type of immune deficiency or some type of underlying lung disease. In fact, I saw just such a case in an elderly male patient recently that prompted me to write this article.
Patients may not always seem very sick with this infection but they almost always have a cough and usually some type of abnormality on their chest x-ray or CT scan of the chest. It is not always easy to make this diagnosis because you need to culture the bacteria from the sputum which can be difficult. In most cases I have found that it is necessary to get specimens directly from the airways of the lung. This procedure is called bronchoscopy and is done with a flexible instrument that is only about 4 millimeters in diameter. The procedure is quick and is done as an outpatient.
Treatment of MAC may require several drugs given over a long period of time. Sometimes it is very difficult to eradicate this organism. Without treatment patients will get progressively sicker and serious damage to the lung tissue can occur. MAC is something we consider in patients who are in the proper clinical setting with chronic cough and x-ray changes.