Septic arthritis due to Streptococcus sanguis.

We report an unusual case of septic arthritis due to Streptococcus sanguis, a member of the viridans group of streptococci that are part of the normal flora of the mouth and upper respiratory tract. Our patient had severe underlying periodontal disease, which likely contributed to his joint sepsis through hematogenous spread. Although viridans streptococci are rare causes of septic arthritis in native joints, they should be considered in the setting of severe periodontal disease.