Is there a role for dual antibiotic treatment with ethambutol and macrolide only, as opposed to three-drug antibiotic therapy, in the treatment of treatment-naive pulmonary MAC without cavitary disease?  

That is a great question, as the role of rifampin (or rifabutin) regarding its relative contribution to the treatment of MAC is not overly clear. Historic data that is a few decades old raised the possibility of better activity when a rifamycin is combined with ethambutol (at least in vitro and furt...

At this time, no. The 2020 multi-society guidelines still recommend rifampin or rifabutin. We have completed enrollment for the MAC2v3 trial, which will help us answer this question more reliably than case reports, small series, and expert pontification.While it is true that rifamycins do not appear...

That is REALLY helpful, Dr. @Wilson! When I was in training (1994 era), we saw lots of MAI bacteremia in AIDS patients, and the standard approach was to use 2 drugs: macrolide + Ethambutol. To my memory, I believe there was some data showing that the addition of Rifabutin really did not have benefi...

It will be interesting to see the results of the MAC2v3 and ENCORE trials (using Arikayce plus azithromycin and ethambutol in naive patients with non-complicated MAC infection). The data from ARISE is looking compelling!