Mycobacterium brisbanense Pulmonary Disease Treated with a Macrolide-Based Multidrug Regimen: A Case Report

A 73-year-old woman with a history of tracheostomy for tracheomalacia and bronchiectasis developed a worsening productive cough with progressive nodular/bronchocentric opacities on computed tomography. She was diagnosed with Mycobacterium brisbanense pulmonary disease based on repeated sputum culture results. Antimicrobial susceptibility testing revealed a low minimum inhibitory concentration for clarithromycin, and whole-genome sequencing confirmed the absence of the erm gene. Owing to repeated smear positivity and clinical progression, macrolide-based multidrug therapy was initiated, resulting in both clinical and radiographic improvements. To our knowledge, this is the first reported case of M. brisbanense pulmonary disease in Japan, thus highlighting its potential pathogenicity.