I was thinking that as well! I remember when I was first diagnosed and there was much discussion about treating with the big 3 even though I had no symptoms. I was told that there was a risk involved with not starting treatment although it was not clear what that was! I was almost ready to go down that road again recently. It would seem that my cold was a blessing in disguise as I would never have produced any samples for testing otherwise. I still have Bronchiectasis but it is such a load off my mind not to have MAC as well.
Mary

My daughter also was not treated and has been symptom free for over a year. ( See my post under hollyw last month). In researching this I found in 3 studies that "untreated patients with MAC lung disease have a high rate of progression with approximately 40 to 60 percent of patients showing signs of clinical and/or radiographic progression over the next 2 to 10 years of follow-up " . They would have treated her when she first presented because she was so sick with cavitations, effusions, severe anemia,and high CRP and ESR all of which are risks for progressive disease. But they didn't get the cultures back until she was out of the hospital and looking like a rose! They opted to not treat at that point and told her just to watch for symptoms. She needs to get follow up testing but is very reluctant as she lost her insurance , so I am gathering data to try to get her to at least get sputums and blood work and maybe a chest xray. She has reduced her risks factors by getting off chronic steroids ( she has chronic severe asthma that is now in good control) , diet and herbal treatments ( she has experimented with going off certain foods that are considered " inflammatory" and found her asthma was better) . I am hoping to find a specialist who takes her current insurance down in Boston ( we live up in Maine).Meanwhile , we work with her local PCP and keep our fingers crossed that she can boost her immune system enough to be one of the 50% who keep from progressing or relapsing.