The sensitivity and the specifity of rapid antigen test in streptococcal upper respiratory tract infections.
BACKGROUND
It is aimed to detect the sensitivity and specificity of rapid antigen detection of group A beta hemolytic streptococci from throat specimen compared with throat culture. The other goal of the study is to help in giving clinical decisions in upper respiratory tract infections according to the age group, by detection of sensitivity and positive predictive values of the rapid tests and throat cultures.


METHODS
Rapid antigen detection and throat culture results for group A beta hemolytic streptococci from outpatients attending to our university hospital between the first of November 2005 and 31st of December 2008 were evaluated retrospectively. Throat samples were obtained by swabs from the throat and transported in the Stuart medium and Quickvue Strep A [Quidel, San Diego, USA] cassette test was applied and for culture, specimen was inoculated on 5% blood sheep agar and identified according to bacitracin and trimethoprim-sulphametaxazole susceptibility from beta hemolytic colonies.


RESULTS
During the dates between the first of November 2005 and 31st of December 2008, from 453 patients both rapid antigen detection and throat culture were evaluated. Rapid antigen detection sensitivity and specificity were found to be 64.6% and 96.79%, respectively. The positive predictive value was 80.95% whereas negative predictive value was 92.82%. Kappa index was 0.91. When the results were evaluated according to the age groups, the sensitivity and the positive predictive value of rapid antigen detection in children were 70%, 90.3% and in adults 59.4%, 70.4%.


CONCLUSIONS
When bacterial infection is concerned to prevent unnecessary antibiotic use, rapid streptococcal antigen test (RSAT) is a reliable method to begin immediate treatment. To get the maximum sensitivity of RSAT, the specimen collection technique used and education of the health care workers is important. While giving clinical decision, it must be taken into consideration that the sensitivity and the positive predictive value of the RSAT is quite lower in adult age group than in pediatric age group.
Faculty of Medicine, Department of Clinical Microbiology, Yeditepe University, Inönü Mahallesi, Kayişdaği Cad, 26 Ağustos Yerleşimi 34755 Kadiköy, Istanbul, Turkey. yesimg@yeditepe.edu.tr
Yesim
Y
Gurol
Hulya
H
Akan
Guldal
G
Izbirak
Zuhal Tazegun
ZT
Tekkanat
Tehlile Silem
TS
Gunduz
Osman
O
Hayran
Gulden
G
Yilmaz
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D000942:Antigens, Bacterial / Q000276:immunology*; D001414:Bacitracin / Q000627:therapeutic use; D001431:Bacteriological Techniques; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008875:Middle Aged; D010612:Pharyngitis / Q000188:drug therapy / Q000276:immunology / Q000382:microbiology; D012141:Respiratory Tract Infections / Q000188:drug therapy / Q000276:immunology* / Q000382:microbiology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000150:complications* / Q000188:drug therapy; D013297:Streptococcus pyogenes / Q000276:immunology* / Q000302:isolation & purification*; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000627:therapeutic use; D055815:Young Adult
D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D001414:Bacitracin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination