Hi Barb, a very excellent source of NTM info is
NTMir.org—judy

NTM is Non-tubercular Mycobacteria, tuberculosis is a well-known strain of mycobacteria, a slow-growing organism that lives in water, soil and living hosts. MAC is Mycobacterium Aviums Complex, of which there are several strains, is everywhere - soil, water, living organisms.

It is impossible to avoid MAC completely, and most people with normal lungs & immune systems are not affected by it. Bronchiectasis affects the ability of our lungs to clear mucus, the warm wet environment in the lungs then allows MAC and other organisms to grow and cause problems. It is a very slow process, and one may be fine for years until a bout of bronchitis or pneumonia further weakens the immune system and allows the bacteria to become a problem. To further complicate matters, most physicians are slow to recognize what is happening (it is fairly rare) and will continue to treat it as pneumonia with short-term antibiotics, which temporarily knocks down the symptoms...and it becomes a cycle.

This is what happened to me - over 5 years, each cold led to worsening "bronchitis" and a severe asthma exacerbation. The doc treated me, sometimes with 2-3 courses of antibiotics and steroids and I got "better" - never quite back to where I was, but able to go on. Finally, nothing was working, I was coughing 23 hours a day, I could barely move... I was sent for an x-ray and a sharp-eyed radiologist recognized pockets (abcesses) characteristic of MAC. I then had a CT which showed both the (suspected) MAC and bronchiectasis and was referred to a pulmonologist who ordered sputum cultures and I was diagnosed with both MAC and pseudomonas. This resulted in 2 months of treatment for pseudomonas, followed by 18 months of antibiotics for MAC. Now I still have MAC in my sputum (at least I did in December) but I am symptom free, and I use 7% saline nebs (shown to be inhospitable to MAC) and Aerobika for airway clearance to stay healthy. I also walk vigorously every day (or play tag with my grandsons) to challenge my lungs.

This is why lung clearance important if you have bronchiectasis, and there is so much conversation about it in the group. Some people use "huff" coughing alone, some use a "flutter" device like Aerobika or Acapella, some use a percussion vest. Some use a nebulizer with an airway relaxer like albuterol, some use saline. It all depends on whether the less drastic measures allow you to bring up mucus to clear the lungs.

Wow - that turned out to be a long answer to a short question. I hope the information helps those of you who are new to this diagnosis. We who have been "around the block" need to be more diligent about spelling out the acronyms we use, I think.
Sue

Barbb.....as explained Already by wonderful others....NTM stands for non tuberculin mycobacterium......and under that heading MAC is one of several hundred identified species...see all the great other responses....and utilize Dr Google on line tdrell