Late-onset Mycobacterium bovis prosthetic knee infection following intravesical BCG therapy

Intravesical BCG is a common treatment for non-muscle-invasive bladder cancer but can rarely cause serious infections. We report the case of a man in his late 60s with bilateral total knee replacements who developed knee pain 18 months after receiving BCG therapy. Evaluation revealed mildly elevated inflammatory markers, negative routine bacterial cultures and acid-fast culture positive for Mycobacterium bovis, resistant to pyrazinamide. Imaging demonstrated periprosthetic lucency without overt mechanical failure. Following multidisciplinary discussion, the patient was treated with isoniazid, rifabutin and pyridoxine without surgical intervention. His symptoms resolved and he remained free of infection at 3 years of follow-up. Few cases of BCG-related prosthetic knee infections have been described. This case underscores that prosthetic joint infection can occur long after BCG therapy and that carefully selected patients may be managed successfully with prolonged antimycobacterial therapy.