Zoonotic tuberculosis presenting as septic arthritis in the emergency department

Tuberculosis is most commonly caused by Mycobacterium tuberculosis ; however, other species within the Mycobacterium tuberculosis complex (MTC), including M. bovis , can cause human disease. M. bovis is typically acquired through exposure to unpasteurized dairy products, contaminated meat, or infected animals and rarely involves the musculoskeletal system. A 71-year-old woman presented to the emergency department with one month of wrist and knee pain and swelling, initially treated as gout. Subsequent synovial fluid cultures grew MTC. Anti-tuberculous therapy was initiated and later adjusted based on later species confirmation of M. bovis . This case highlights a rare presentation of M. bovis septic arthritis diagnosed via synovial fluid analysis and emphasizes the importance of considering MTC in patients with subacute joint symptoms and relevant travel or exposure histories, as treatment regimens differ from those of M. tuberculosis .