Hi Kee, welcome to the group - first of all, MAC is Mycobacterium Aviums Complex, a type of non-tubercular mycobacteria (NTM). It is a slow-growing bacteria that likes to colonize in warm, moist places. Most lungs are very good at ejecting mucus through the cough reflex, but those with bronchiectasis and/or fibrosis are damaged, and mucus tends to get "stuck" and provide a place for germs to grow. Mycobacteria and Pseudomonas are 2 of the most common.

The problem with waiting to be symptomatic is that an infection can sneak in and get a good head start before you will notice a problem. If you want to be proactive, you might want to find a pulmonologist experienced in the treatment of fibrosis &/bronchiectasis who can evaluate your CT, oxygen sats & spirometry (lung input & output.) Based on the findings, it may be recommended for you to do some airway clearance to keep most of the mucus out of your lungs. If that is recommended, you can come back here and talk about what/when/how.

Do you think you can ask one of your docs for referral to a pulmonologist?
Sue