[Effectiveness of rapid antigen test with throat gargle in detecting group A beta-hemolytic streptococci].
OBJECTIVE
The most important disadvantage of rapid antigen tests (RAT) is low sensitivity for the diagnosis of group A beta-hemolytic streptococci (BHS). We determined the sensitivity, specificity, positive and negative predictive values of RAT in gargling samples.


METHODS
The study included 106 patients (53 females, 53 males, mean age 22+/-12 years; range 16-65 years) with an initial diagnosis of tonsillopharyngitis. Swab samples were taken from the posterior pharyngeal wall and tonsil surface with a sterile cotton swab. Then, gargle samples were obtained by gargling for 10 seconds with sterile 0.9% NaCl to be examined by the RAT for group A BHS. Throat cultures were processed using standard microbiologic techniques.


RESULTS
Throat cultures were positive in 12 patients (11.3%) and negative in 94 patients (88.6%). Rapid antigen test yielded five positive (4.7%) and 101 negative (95.2%) results. The sensitivity and specificity rates of RAT with throat gargling were 41.7% and 100%, with positive and negative predictive values of 100% and 93.1%, respectively.


CONCLUSIONS
Despite satisfactory specificity, positive and negative predictive rates of RAT with throat gargling, its low sensitivity limits its use for the diagnosis of group A BHS.
Yilmaz
Fahrettin
F
Department of Otolaryngology, Izzet Baysal Medicine Faculty of Abant Izzet Baysal University, Bolu, Turkey. yilmazfahrettin@yahoo.com
Karabay
Oğuz
O
Ince
Nevin Koç
NK
Ekerbiçer
Hasan
H
Koçoğlu
Esra
E
D000293:Adolescent; D000328:Adult; D000368:Aged; D000942:Antigens, Bacterial / Q000032:analysis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014066:Palatine Tonsil / Q000382:microbiology; D010614:Pharynx / Q000382:microbiology*; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000276:immunology / Q000302:isolation & purification*; D014069:Tonsillitis / Q000175:diagnosis* / Q000382:microbiology; D055815:Young Adult
D000942:Antigens, Bacterial