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MAC Pulmonary Disease — SCE Infectious Diseases MCQ

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ModerateTuberculosisMAC Pulmonary DiseaseSCE Infectious Diseases

A 50-year-old man presents with progressive shortness of breath and CT chest shows tree-in-bud nodularity and bronchiectasis predominantly in the right middle lobe and lingula. Sputum cultures on three occasions grow Mycobacterium avium complex (MAC). He is a non-smoker with no immunodeficiency. He is symptomatic. What is the recommended treatment regimen?

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Correct answer: A — Rifampicin, Ethambutol, and Azithromycin (or Clarithromycin) three times per week for at least 12 months of culture-negative sputum

Nodular bronchiectatic MAC lung disease (the most common presentation in immunocompetent patients) is treated with a three-times-weekly intermittent regimen: Rifampicin 600 mg, Ethambutol 25 mg/kg, and Azithromycin 500 mg (or Clarithromycin 1000 mg) on Monday/Wednesday/Friday. Treatment continues until at least 12 months after the last positive sputum culture. Cavitary MAC disease requires daily dosing and consideration of IV Amikacin. Macrolide susceptibility testing is essential as macrolide resistance renders the regimen ineffective.

Reference: BTS 2017 – NTM pulmonary disease; ATS/IDSA 2020 – NTM guidelines