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March 1996

Optical Immunoassay for Rapid Detection of Group A β-Hemolytic Streptococci: Should Culture Be Replaced?

Author Affiliations

From the Department of Pediatrics, University of Virginia Medical Center, Charlottesville.

Arch Pediatr Adolesc Med. 1996;150(3):245-248. doi:10.1001/archpedi.1996.02170280015002

Objective:  To evaluate an optical immunoassay rapid antigen test to detect group A β-hemolytic streptococci directly from throat swab specimens.

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 laboratory in a primary care center at a university teaching hospital.

Patients:  Two hundred sixty-two outpatients with pharyngitis.

Main Outcome Measure:  The results of the optical immunoassay rapid antigen test were compared with results of standard aerobic culture.

Results:  Sixty-two (24%) of 262 samples were culture-positive; 48 of these 62 were positive by the optical immunoassay rapid test (sensitivity, 77%). Of the 200 culture-negative samples, seven (4%) were positive by the rapid test (specificity, 96%).

Conclusion:  The optical immunoassay performed well, but like other rapid tests, is not sensitive enough to replace standard culture for detection of group A β-hemolytic streptococci.(Arch Pediatr Adolesc Med. 1996;150:245-248)