@alm2019 – I'm a little late to the party here, but take a look at this video from 2016 from a NTM conference. https://youtu.be/U1ZmJAQlgLw
he gist of it is that it seems what is identified as intracellulare may be chimaera, not all testing differentiates between the bugs well. Chimaera is another of the slow-growing NTM, so the treatment of the two is similar, just be sure sensitivity testing has been done. To see all the videos from that conference, go to https://www.nationaljewish.org/ntmvideos2016 .