Objectives To identify the risk factors of the development and exacerbation of NTM infection in patients with rheumatic diseases.

Methods Among 7013 patients with rheumatic diseases visiting Toho University Ohashi Medical Center and Tokyo Medical Center, 20 patients were enrolled in this study by fulfilling the diagnostic criteria of NTM infection by The Japanese Society for Tuberculosis and The Japanese Respiratory Society, and being followed-up for more than 1 year. The medical records of enrolled patients were retrospectively reviewed.

Results Eleven patients with rheumatoid arthritis, 4 patients with vasculitis, 3 patients with Sjögren's syndrome and 1 patient with dermatomyositis and systemic lupus erythematosus for each were enrolled in this study. Mycobacterium avium complex (MAC) was detected in 13 patients, M. chelonae in 2 patients, M. abscessus and M.kansasii in 1 patient each, and undetermined mycobacterium in 3 patients. Notably, bronchiectasis was the predominant pulmonary complication observed in 13 patients, and interstitial lung disease was observed in 5 patients. Although 7 patients experienced the exacerbation of NTM during the observation period, immunological state on NTM diagnosis including peripheral blood leukocyte (median 5.8×10³ versus 7.0×10³/μL; p=0.72), lymphocyte (median 1.3×10³ versus 1.1×10³/μL; p=0.10) and the serum IgG level (median 1379 mg/dL versus 1207 mg/dL; p=0.20) were within normal ranges and comparable between ever and never exacerbated patients, respectively, as well as the treatments for rheumatic diseases such as glucocorticoids and biological agents.

Conclusions NTM infection in patients with rheumatic diseases develops based on the dysfunction of pulmonary barrier rather than the systemic immunosuppression.

Disclosure of Interest None declared