Razi Journal of Medical Sciences

Background: Determining the etiologic agents of septic arthritis is very important. The aim of the present study was to determine group A streptococcal polysaccharide antigens in synovial fluid of patients with arthritis.

Methods: A cross sectional study was conducted upon 52 cases with acute mono arthritis in Hazrat-e-Rasool Akram hospital in Tehran, Iran (2010-2012).Gram staining, culture and rapid antigen tests were performed (LPA) for H. influenza, S. pneumonia, group B streptococci, N. meningitidis, E.coli and Group A streptococcal polysaccharide antigens (Cusabio company Austria liscence, China, ELISA) was searched in synovial samples (negative smear and culture). p value <0.05 was considered valuable.

Results: Septic arthitis was diagnosed in 34.5% that included positive culture or gram staining in 15%, positive rapid antigen test (LPA) in 5.7%, positive group A streptococcal polysaccharide antigens in 3.8% of cases with negative results for other tests.

Conclusions: Septic arthitis was diagnosed in 34.6% of cases. Only 15% of cases had positive culture or gram stain (mainly S. aureus, S. pneumonis), 5.7% were diagnosed by rapid antigenic tests (LPA) and group A streptococcal polysaccharide antigens (ELISA) test was positive in 3.8% of the remaining cases (negative smear and culture). By addingthenew diagnostic methods to the conventional culture tests for detecting common bacterial antigens (especially streptococcus), the role of infectious organisms in evolution of acute arthitis would be elucidated better. Streptococcal polysaccharide antigens in synovial fluid are not defined by the immune system. The irreversible cardiac, renal, and neurologic complications are probable. Optimal treatment of proved streptococcal cases is recommended.