Tuberculosis osteomyelitis in an old fused hip; activated by prednisolone, salazosulfapyridine, and low-dose methotrexate therapy in a patient with rheumatoid arthritis.

Osteoarticular tuberculosis can occur in patients with rheumatoid arthritis (RA) receiving immunosuppressive therapy. Here, we describe a case of tubercular osteomyelitis in an old fused hip of a patient with RA who received prednisolone, salazosulfapyridine (SASP), and low-dose methotrexate (MTX). A 77-year-old man with a 4-year history of RA was admitted with a complaint of general fatigue. His symptoms of RA had been well controlled with a combination of prednisolone, SASP, and low-dose MTX. Because the laboratory data showed an increase in serum C-reactive protein levels, we suspected pneumonia. There was expansion of a pre-existing consolidation in the right lower lobe of his lung on chest computed tomography, and the sputum culture was positive for Klebsiella oxytoca. His family physician prescribed empiric antibiotics for pneumonia. Although the QuantiFERON® test result was positive, the acid-fast bacillus staining result was negative in the sputum. He started complaining of pain in his left hip, where arthrodesis was performed for an unknown reason at the age of 20 years. Sonographic examination of his left thigh revealed fluid collection. The aspiration culture of the fluid was positive for Mycobacterium tuberculosis. He was initiated on rifampicin, isoniazid, pyrazinamide, and ethambutol. Surgical debridement of the fused left hip was performed twice along with a removal of previously implanted materials. Although infrequent, osteoarticular tuberculosis can occur during immunosuppressive therapy, especially in elderly patients. Physicians should be aware of a history of possible tuberculosis infection, such as hip arthrodesis, when prescribing MTX along with SASP and corticosteroid in the elderly.