Citrobacter koseri as a cause of early periprosthetic infection after primary total hip arthroplasty.

Periprosthetic joint infection in the acute setting is usually caused by gram-positive species and remains a major problem facing total joint surgeons. We report a case of a 53-year-old male who presented with drainage 3 weeks after primary total hip arthroplasty. Citrobacter koseri was cultured from an infected hematoma in his deep tissues. Surgical treatment included irrigation and debridement with femoral head and liner exchange. He received a 6-week course of ertapenem and is currently asymptomatic. We present C. koseri as a rare cause of acute periprosthetic infection and offer an effective treatment protocol.