Tuberculous arthritis of the hip with Staphylococcus aureus superinfection

Skeletal tuberculosis (TB) accounts for a small percentage of all cases of TB. It is often difficult to diagnose, especially in the hip joint. TB arthritis can be masked by superinfection with other pathogens, leading to a delay in diagnosis and treatment. Trauma or surgery is a reported risk factor of TB arthritis. In contrast, descriptions of TB arthritis after a closed bone fracture are rare. We herein report a case involving an 81-year-old woman with septic arthritis superinfected with methicillin-resistant Staphylococcus aureus (MRSA) and Mycobacterium tuberculosis. Three months before presentation, she sustained a bone fracture of the left femur and was treated conservatively without surgery. She developed a fever at another hospital and was transferred to our institution. Computed tomography revealed the presence of abnormal fluid around the left hip joint. MRSA was detected from the fluid and blood cultures. The patient was diagnosed with MRSA arthritis and treated with antibiotics and surgical drainage. However, her fever persisted, and the abscess further developed and enlarged around the left hip. It was punctured and cultured again. Three weeks later, Mycobacterium tuberculosis was identified from the abscess culture. The septic arthritis was confirmed to have been caused by MRSA and M. tuberculosis. After the initiation of antituberculosis therapy, her fever subsided and the treatment was continued. This case demonstrates that the diagnosis of TB arthritis can be hindered by the existence of other pathogens and that TB arthritis can occur at a closed fracture site in the hip joint.