Sternoclavicular Septic Arthritis Caused by Parvimonas micra and Fusobacterium nucleatum Infection with Intra-articular Corticosteroid Administration.

Sternoclavicular septic arthritis is a rare form of septic arthritis that can lead to fatal complications, such as abscess formation and mediastinitis, in the absence of prompt diagnosis and appropriate treatment. A man in his 40s presented with pain in the right sternoclavicular joint area, and after a joint injection of steroids was administered, he was diagnosed with septic sternoclavicular arthritis caused by Parvimonas micra and Fusobacterium nucleatum. Gram staining of a specimen obtained from the abscess formation area led to early suspicion of anaerobic infection, and appropriate antibiotics were administered.