A 67-year-old immunocompetent man presented with a periprosthetic infection 4 months after a left total knee arthroplasty. Repeated aspirations failed to show any organism growth. After irrigation and debridement with polyethylene exchange, there was minimal clinical improvement. Subsequently, the patient developed an arthrocutaneous fistula, which prompted a 2-stage revision arthroplasty. Mycobacterium cosmeticum grew on the culture specimens taken during this procedure, and the patient was treated with 6 months of antibiotics.
To our knowledge, this is the first reported case of an M. cosmeticum prosthesis-related infection. The patient recovered well following a 2-stage revision arthroplasty and treatment with a Mycobacterium species-specific antibiotic.