Acute septic arthritis due to Streptococcus sanguis.

Objective: To present a case of acute septic arthritis due to Streptococcussanguis, a member of the viridans group streptococci.

Methods: A 73-year-old woman presented with fever and increasing swelling and pain of the right knee several weeks after she had been treated for severe periodontal disease. Arthrocentesis yielded purulent synovial fluid. S. sanguis was isolated in synovial fluid cultures, and the patient was treated with intravenous cefotaxime for 3 weeks and repeated aspiration of the knee joint with gradual resolution of fever, joint swelling and effusion.

Conclusions: Although S. sanguis is believed to be a rare cause of septic arthritis in native joints, it should be considered in the differential diagnosis of this disorder, especially in patients with recent treatment of severe dental caries and periodontal disease.