Acute respiratory deterioration in rheumatoid arthritis-associated interstitial lung disease associated with pulmonary Mycobacterium abscessus infection: a case report.

Nontuberculous mycobacteria (NTM) are important pathogens in patients with chronic lung diseases, including rheumatoid arthritis-associated interstitial lung disease (RA-ILD). Although acute exacerbations of ILD associated with NTM infection have been reported sporadically, cases involving pulmonary Mycobacterium abscessus infection remain extremely limited. We describe a fatal case of acute respiratory deterioration in a patient with RA-ILD following pulmonary infection with M. abscessus. A 76-year-old man with longstanding RA-ILD developed pulmonary NTM disease initially caused by Mycobacterium avium complex and subsequently complicated by M. abscessus infection. Intensive multidrug induction therapy led to transient clinical and radiographic improvement. However, two weeks after discharge, he was readmitted with rapidly progressive hypoxemic respiratory failure and newly developed bilateral diffuse ground-glass opacities on chest computed tomography. A comprehensive evaluation did not identify alternative infectious etiologies, and the overall findings were considered consistent with clinically suspected acute exacerbation of RA-ILD associated with pulmonary M. abscessus infection, although progressive pulmonary M. abscessus disease could not be completely excluded. Despite corticosteroid pulse therapy and broad antimicrobial coverage, the patient died six days after readmission. Subsequent analysis confirmed M. abscessus subsp. abscessus with resistance to macrolides and imipenem/cilastatin. This case highlights the diagnostic challenges in distinguishing acute exacerbation of RA-ILD from progressive pulmonary M. abscessus disease, raises the possibility that M. abscessus infection may be associated with acute respiratory deterioration in patients underlying RA-ILD, and underscores the importance of early recognition and optimal management of NTM infections in this high-risk population.