OPTICAL IMMUNOASSAY FOR RAPID DETECTION OF GROUP-A BETA-HEMOLYTIC STREPTOCOCCI - SHOULD CULTURE BE REPLACED

Objective: To evaluate an optical immunoassay rapid antigen test to de tect group A beta-hemolytic streptococci directly from throat swab spe cimens. Design: Criterion standard with ''blinded'' comparison. Double -swab pharyngeal samples were obtained; one swab was cultured and the other was used for the rapid antigen test. Setting: Microbiology labor atory in a primary care center at a university teaching hospital. Pati ents: Two hundred sixty-two outpatients with pharyngitis. Main Outcome Measure: The results of the optical immunoassay rapid antigen test we re compared with results of standard aerobic culture. Results: Sixty-t wo (24%) of 262 samples were culture-positive; 48 of these 62 were pos itive by the optical immunoassay rapid test (sensitivity, 77%). Of the 200 culture-negative samples, seven (4%) were positive by the rapid t est (specificity, 96%). Conclusion: The optical immunoassay performed well, but like other rapid tests, is not sensitive enough to replace s tandard culture for detection of group A beta-hemolytic streptococci.