How is NTM Diagnosed?
Nontuberculous mycobacteria can be very difficult to diagnose. Unfortunately, this difficulty sometimes delays initial diagnosis until after the patient has had recurrent infections. This may make treatment more difficult because prior use of single drug therapy may have created some drug resistance. Also, recurrent infections and associated inflammation may have resulted in additional damage to the respiratory system.
The diagnosis of NTM involves the following:
Sputum culture - sputum is cultured for acid fast bacilli (AFB), which is the basic test to identify mycobacteria. For accurate identification of the strain of NTM and drug sensitivities, testing should be done at a highly specialized laboratory, which can tell your doctor which drugs will work (drug sensitivity) and which ones will not work (drug resistance) on the strain of NTM that you have. Equally important is the need to determine which combination of drugs must be used in order to minimize risk of developing drug resistance, which is a common problem when NTM infections are treated with single drug therapies. If you have trouble coughing up sputum (also called mucus or phlegm), your doctor may decide to perform a bronchoscopy to obtain the needed sample.
Chest CT (computed tomography) - A CT (CAT) scan is a three-dimensional image generated from a large series of two-dimensional x-ray images taken around a single axis of rotation. Chest x-rays alone provide rudimentary identification of lung ailments. A CT scan provides the doctor with a detailed look at the extent and location of disease and is an important diagnostic tool. It can show mucus-filled airways, which appear as white spots on the images (sometimes referred to as "tree-in-bud" because of their branch-like appearance). NTM diagnosis and follow-up generally requires a high resolution CT scan without contrast.
Medical History - Knowing what illnesses you have had, including childhood illnesses, may provide your doctor with additional understanding of why certain underlying lung conditions exist. Click here for tips on generating a family health history.