I have been diagnosed with MAC lung disease. The first CT scan showed a 1 cm nodule in the lower left lung that was suspicious for lung cancer along with many tiny nodules in all the lobes. A recent CT scan showed that after 8 wks of antibiotic therapy (azithromycin, rifampin and ethambutol three times a week) all the nodules are shrinking somewhat, including the one that was suspicious for cancer. However, there are more of the nodules than there were in the first CT scan. The antibiotic therapy wasn t start for about 4 weeks after the first CT scan. Is it possible the bacteria grew in that period of time? Not sure what to make of it.