Group C streptococcal arthritis: case report and review.

Streptococci account for approximately 15%-20% of cases of nongonococcal septic arthritis. The majority of these are due to group A streptococci, but group B and group G streptococci are being isolated more frequently. We present a case of group C streptococcal arthritis and summarize nine additional cases reported in the literature. The group C streptococci include the large colony of Voges-Proskauer-negative bacteria (Streptococcus equi, Streptococcus equisimilis, Streptococcus zooepidemicus, and Streptococcus dysgalactiae) as well as as the minute colony of Voges-Proskauer-positive Streptococcus anginosus ("Streptococcus milleri") group C organisms. Any joint may become infected, but joints affected by preexisting rheumatologic abnormalities are more frequently involved. Bacteremia was documented in five of the 10 patients. One patient had an associated pneumonia, and another patient had an associated acute aortic valve endocarditis. None of the infections involved a prosthetic joint or an overlying cellulitis, associations reported for group G streptococcal arthritis. Surgical drainage of the infected joint was required in six of the 10 patients. We concluded that the presence of two groups of organisms sharing the same Lancefield group antigen necessitates the careful identification of isolates to determine potential clinical differences.