The NTM infections are "somewhat" responsive to each of the 3 antibiotics, so if one of the 3 weakens the bacteria, the others will kill it off. Otherwise, some of the bacteria dies, but the strongest or most persistent go into hiding & survive - with an increased resistance to azithromycin - this is how "superbugs" like MRSA get stronger over time.

Sometimes, when one has issues with either the rifampin or ethambutol, the docs will continue the others - possibly adding Amikacin or another inhaled antibiotic as well. And sometimes, particularly with M. Abscessus, the bacteria may resistant to the antibiotics already, based on susceptibility testing. Then different drugs will be used, possibly via a PICC line or IV.

There have been a few small scale studies that indicate some strains of NTM can be fought with only one or two drugs, but the results have not been consistent enough to alter the standard protocol.

In any case, airway clearance is important along with the drug therapy, to avoid giving bacteria a good breeding ground.

Are you on the antibiotic regimen now?
Sue