Hi D - I don't know about "harder to treat" - it is just that a few different meds may be used. If there is any place to get the "exact" treatment for M lentiflavum, it is a clinic like NJH. Just remember, mycobacteria, with few exceptions, grow VERY slowly, so the risk of waiting a month or six weeks to start treating is low.

What would I do in your place? Use the Tobramycin - it at least will keep other stuff from growing. Do my airway clearance every day, using 7% saline (if tolerated.) 7% saline has been shown to suppress the growth of mycobacterium, and even reduce it in some cases. Wait to start any new antibiotics until after evaluation.

Are you comfortable waiting?
Sue