323 - First case of Prosthetic joint infection due to Nocardia veterana-elegans

Background: Nocardia are Gram-positive filamentous bacteria that cause Nocardiosis, a rare opportunistic infection. The most common site of infection is the lungs, with metastatic spread usually to the central nervous system. Prosthetic joint infection due to Nocardia is very rare.

Methods: We report the first case of prosthetic joint infection due to Nocardia veteran-elegans, and review the literature regarding Nocardia septic arthritis, with particular attention to prosthetic joint infection.

Results: The patient was a 35 year old male with history of Hodgkin's Lymphoma for which he received chemotherapy previously, poorly controlled diabetes, motor vehicle accident in 2003 with right open tibial plateau fracture requiring hardware placement, who was admitted with a two week history of right knee pain and swelling. Knee aspiration revealed purulent fluid and synovial culture grew Nocardia species. He underwent right knee arthrotomy and debridement with removal of hardware. The Nocardia species was speciated as N. veterana-elegans, sensitive to trimethoprim/sulfamethoxazole, linezolid, clarithromycin, imipenem and amikacin. He was placed on oral linezolid for four weeks, which was then switched to oral trimethoprim/sulfamethoxazole, with a plan for a six month course of therapy. He has completed two months of therapy thus far and is doing well clinically.
Nocardia is an uncommon cause of septic arthritis. We found only 37 cases reported in the English literature thus far. Amongst these, only six involved prosthetic joints, including our case, which is the first one to be caused by N. veterana-elegans.Three cases were caused by N. nova and one each by N. farcinica and asteroides. Septic arthritis due to Nocardia has a favorable outcome with a combination of surgical debridement and prolonged antimicrobial therapy of three to six months. For prosthetic joint infections, removal of hardware seems to carry a better prognosis. Trimethoprim/sulfamethoxazole is the preferred antimicrobial, including for bone and joint infection, although susceptibilities can vary amongst the different species.

Conclusion: Nocardia is an uncommon cause of septic arthritis. Prosthetic joint infection is very rare. Prognosis is fair with a combination of hardware removal and prolonged antibiotic therapy.