Thanks for the responses. Yes, they have identified exact species and done sensitivity testing – switched from clarithromycin to azithromycin many months ago because it showed better response. Doc is trying to hold tobramycin "in reserve" but we talked this week and he is getting closer to trying it if next CT doesn't show improvement and next sputum samples are still positive. I am truly getting frustrated, so it's great to hear from people here. I took a 30 minute medium paced walk this morning and was pleased that I could talk to my friend as we walked – 3 months ago that was impossible. Does anyone have a feeling for how much of my fatigue is MAC, and how much is these infernal antibiotics?