I did convert to negative sputum culture after 12 months on the Clarithromycin, Rifampin and Ethambutol treatment. I still have 4 months to go to complete 12 months of treatment after the first negative. I had 2 cavities prior to treatment and now I have one very small cavity which I hope will collapse by the next CT scan. I am faithful in doing nebs and airway clearance at least 2X/day. Hope this helps