I too have been on 3 meds for 1 year and the sputum comes back negative but the CT and xrays show the cavities and other area not changing or getting worse. I had a scope put in my lungs to take biopsies and fluid samples. They came back positive after 9 days for MAC. So they sent the cultures to NJH for a susceptibility test and found out 2 of the drugs I was taking were resistant when tested separately and only moderate together. So now they are talking either trying Clofazimine or surgery. My local ID doc is sending all my notes and scans to NJH for second opinion. Has anyone else taken Clofazimine? It is going to take 1 month to get the drug as you can only get it from the FDA because it is not on the market anymore but it is sometimes used for TB when nothing else works.