Purpose of review
Nontuberculous mycobacterial disease, especially pulmonary disease, is increasingly encountered by clinicians. Therapy of the most common nontuberculous mycobacterial pathogen, Mycobacterium avium complex, improved with the introduction of macrolide-containing regimens, but treatment for this and most other nontuberculous mycobacterial pathogens remains difficult.
Treatment trials with macrolide-containing regimens for Mycobacterium avium complex lung disease have yielded generally favorable outcomes. Studies consistently show that in-vitro susceptibility to macrolides remains the only in-vitro susceptibility for Mycobacterium avium complex that correlates with in-vivo response. Patients who have macrolide-resistant Mycobacterium avium complex isolates are much harder to treat and have higher mortality than patients with macrolide-susceptible isolates. Studies also consistently show that patients who fail therapy, even those who remain macrolide susceptible in vitro, are more difficult to treat than patients without previous therapy.
There have been no significant treatment advances for Mycobacterium avium complex lung disease, and nontuberculous mycobacterial disease in general, since the advent of the newer macrolides. It has become clear that the best opportunity for treatment success is the first treatment effort. It is also clear that protection against the emergence of macrolide-resistant Mycobacterium avium complex isolates is critically important. For further progress in the treatment of these pathogens, new and more active drugs must be developed.