treat refractory MAC with amikacin

This patient with a pansusceptible MAC nodular bronchiectatic pulmonary disease in whom therapy failed after at least 6 months with good adherence to guideline-based therapy should receive the addition of amikacin liposome inhalation suspension (ALIS) to the treatment regimen (choice B is correct).

Refractory disease is defined as sputum culture remaining positive after 6 months of guideline-based therapy with the patient being compliant with treatment and generally stable. In a randomized controlled trial of adults with amikacin-susceptible MAC lung disease and MAC-positive sputum cultures despite at least 6 months of guideline-based therapy (as in this patient treated with azithromycin, rifampicin and ethambutol), the use of ALIS achieved greater culture conversion by month 6 compared with guideline-based therapy alone, with comparable rates of serious adverse events. Therefore, continuation with current therapy and expecting culture conversion at 12 months is unlikely to occur, suggesting the need for additional treatment (choice C is incorrect).

Reported side effects of ALIS include hoarseness, throat irritation, bitter taste, and thrush, and less frequently ototoxicity, nephrotoxicity, and vertigo. The 2020 clinical practice guidelines recommend that patients with macrolide-susceptible MAC pulmonary disease should receive treatment for at least 12 months after culture conversion. However, clinical practice guidelines do not recommend the inclusion of inhaled amikacin (parenteral formulation) or ALIS as part of the initial treatment of nodular bronchiectatic pulmonary disease. Change in therapy to clarithromycin and rifabutin is not recommended because azithromycin-based regimens have better tolerance, fewer drug interactions, lower pill burden, single daily dosing, and equal efficacy (choice D is incorrect).

However, when azithromycin is not available or not tolerated, clarithromycin is an acceptable alternative. The addition of linezolid has been considered for other nontuberculous mycobacteria, such as Mycobacterium kansasii or Mycobacterium abscessus, particularly when rifampicin resistance has been identified. However, linezolid is not considered an alternative treatment as part of initial therapy for refractory disease and has not been recommended for patients with MAC pulmonary infection (choice A is incorrect). In patients with M kansasii or M abscessus, once daily dosing of linezolid is recommended due to the high rate of drug-related adverse reactions associated with twice-daily dosing as recommended for other acute infections.1

Footnotes

  1. SEEK Questionnaires ↩