MAI drug resistant??

After 7 full month's of taking the big 3 my monthly sputum tests have come back positive again. Dr Anderson at Washington University in St. Louis is going to test me for being resistant to the big 3. What will happen if I am drug resistant? Anyone have that experience? I was diagnosed with MAI Jan 2017 and started the drugs on 1-20-17. Went to Dr. Joseph Craft my cardiologist for routine check up and he thought it was very strange because I was the 3rd MAI patient he'd seen in 6 mo's in the St. Louis, Mo. area. Dr Craft said we were all female, white, and in our mid 70's. Any of you from the St. Louis area that go to Dr. Craft? So upset over not being able to get a negative sputum culture after 7 mo's. Need some encouragement???