Abstract
Antibody to specific cell-wall carbohydrate of group A streptococci in human sera was determined by enzyme-linked immunosorbent assay (ELISA) with enzyme-treated whole cells and purified group A carbohydrate (ACHO) as antigens. The optimal concentration of enzyme-treated whole bacterial cells to coat wells was 2 x 10(8) cells/ml and for purified ACHO antigen the optimal concentration was 1 microgram/ml. Sera from patients with acute rheumatic fever and acute glomerulonephritis were screened for the presence of C-carbohydrate antibodies. Patients with acute post-streptococcal complications showed significantly higher titres of antibody when compared with normal healthy individuals. ELISA results were also compared with purified ACHO as an antigen; this showed a highly significant correlation (r = 0.73). Results showed that measurement of the anti-ACHO antibody by ELISA with enzyme-treated whole cells can be a useful, reliable and simple method for serological diagnosis of group A infection and sequelae.