The first case of septic arthritis of the knee caused by Eggerthia catenaformis.

Eggerthia catenaformis has been reported as a human pathogen. We present the first case of the primary knee infection caused by Eggerthia catenaformis in a 23-year-old male patient with a knee infection, after primary anterior cruciate ligament reconstruction. Eggerthia catenaformis was confirmed by MALDI-TOF mass spectrometry from synovial fluid. The dental focus was excluded. The isolated bacterial strain showed sensitivity to all of the tested antimicrobials. However, for successful management of knee infection, besides culture-directed antibiotics therapy, arthroscopic debridement and lavage were necessary.