Septic arthritis caused by Nocardia asiatica: a case report and narrative review.

Nocardia asiatica is a rare opportunistic pathogen typically associated with pulmonary and central nervous system infections; however, musculoskeletal infections are uncommon. We report a case of septic arthritis caused by N. asiatica in a 72-year-old man with a history of chronic obstructive pulmonary disease (COPD) and pneumoconiosis. The patient presented with subacute knee swelling following a recent episode of pneumonia. Gram staining of intraoperative synovial samples revealed branching filamentous organisms, and the isolate was identified as N. asiatica by mass spectrometry. Although the patient was transferred to another center during the initial phase of management, follow-up information obtained after discharge confirmed a favorable clinical recovery without recurrence. Our report contributes to the limited literature on the clinical manifestations, organ tropism, and antimicrobial susceptibility patterns associated with N. asiatica infection.