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 detect group A beta-hemolytic streptococci directly from throat swab specimens.


METHODS
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.


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


METHODS
Two hundred sixty-two outpatients with pharyngitis.


METHODS
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%).


CONCLUSIONS
The optical immunoassay performed well, but like other rapid tests, is not sensitive enough to replace standard culture for detection of group A beta-hemolytic streptococci.
Schlager
T A
TA
Department of Pediatrics, University of Virginia Medical Center, Charlottesville, USA.
Hayden
G A
GA
Woods
W A
WA
Dudley
S M
SM
Hendley
J O
JO
D000293:Adolescent; D000942:Antigens, Bacterial / Q000276:immunology*; D001431:Bacteriological Techniques; D016009:Chi-Square Distribution; D002648:Child; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008297:Male; D010612:Pharyngitis / Q000175:diagnosis / Q000276:immunology* / Q000382:microbiology; D010614:Pharynx / Q000276:immunology / Q000382:microbiology; D013290:Streptococcal Infections / Q000175:diagnosis / Q000276:immunology* / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000276:immunology* / Q000302:isolation & purification
D000942:Antigens, Bacterial