Knee joint infection represents an emergency case at every age. Joint infection occurs frequently after trauma or joint surgery. The infection can be caused by numerous bacteria, viruses, or yeasts; however, Staphylococcus aureus is identified as the cause in 85-95 % of joint infections. Early treatment is important for patient outcome. In addition to synovectomy and therapeutic arthroscopy, antibiotic therapy is essential and should be started after sample recovery.