[Septic arthritis as an initial manifestation of endocarditis]. / Septische Arthritis als Erstmanifestation einer Endokarditis.

A 60-year-old female patient was admitted to the hospital with high fever and an acute onset of pauciarticular arthritis. Clinical examination and ultrasound imaging of the right knee demonstrated a severe synovitis with a large synovial effusion and a Baker's cyst. Arthrocentesis showed an opaque viscous synovial fluid with a highly elevated white blood cell count. In synovial fluid cultures and in serial blood cultures Aerococcus viridans (Av) was detected. Further examination revealed a mitral valve endocarditis as the origin of the septicemia. This case report is the first one to describe the association of an endocarditis and a septic arthritis due to Av.