Searching group A streptococcal polysaccharide antigens in synovial fluid of patients with arthritis

Diagnosing the etiologic causes for septic arthritis is very important. The main goal of study was to determine the group A streptococcal polysaccharide antigens in synovial fluid of patients with arthritis. A cross sectional study was performed upon 52 cases with acute mono arthritis in Hazrat-e-Rasool hospital in Tehran; Iran (2010-2012). Techniques used were: Gram stain/culture and rapid antigen tests (LPA) for H. influenza، S. pneumonia، group B streptococci، N. meningitidis، and E. coli and for Group A streptococcal polysaccharide antigens (Cusabio company; Austria license، China، ELISA) were searched in synovial samples (negative smear and culture). P value <0. 05 was considered valuable. Septic arthitis was diagnosed in 34. 5% (including positive culture or gram staining in 15%، rapid antigen test (LPA) in 5. 7%)، and positive group A streptococcal polysaccharide antigens was observed in 3. 8% of cases with negative results for other tests. Septic arthitis was diagnosed in 34. 6% of cases. Also 15% of cases had positive culture or gram stain (mainly S. aureus، S. pneumonis)، 5. 7% were diagnosed by rapid antigenic tests (LPA). Group A streptococcal polysaccharide antigens (ELISA) test was positive in 3. 8% of remaining cases (negative smear and culture). By adding the new methods of searching for the common bacterial antigens (especially streptococcus) to the conventional culture tests، the role of infectious organisms in evolution of acute arthitis would be elucidated more clearly. Streptococcal polysaccharide antigen in synovial fluid is not defined by immune system. The irreversible cardiac، renal، neurologic complications are probable. Optimal treatment of the proved streptococcal cases is recommended.