The sensitivity and the specifity of rapid antigen test in streptococcal upper respiratory tract infections Yesim Gurol a, * , Hulya Akan b,1 , Guldal IzbI ˙ rak b,2 , Zuhal Tazegun Tekkanat a,3 , Tehlile Silem Gunduz a,4 , Osman Hayran c,5 , Gulden Yilmaz a,6 a Yeditepe University, Faculty of Medicine, Department of Clinical Microbiology, I ˙ no ¨ nu ¨ Mahallesi,Kayıs¸ dag ˘ı Cad.,26 Ag ˘ustos Yerles¸ imi, 34755 Kadıko ¨ y, I ˙ stanbul,Turkey b Yeditepe University, Faculty of Medicine, Department of Family Medicine, I ˙ no¨nu¨ Mahallesi,Kayıs¸ dag ˘ı Cad.,26 Ag ˘ustos Yerles¸ imi, 34755 Kadıko ¨y, I ˙ stanbul,Turkey c Yeditepe University, Faculty of Health Sciences, I ˙ no ¨ nu ¨ Mahallesi,Kayıs¸ dag ˘ı Cad.,26 Ag ˘ustos Yerles¸ imi, 34755 Kadıko ¨ y, I ˙ stanbul,Turkey 1. Introduction Sore throat is one of the most common complaints reported in the first-step healthcare services [1–7]. Generally,it results from the infection of the pharynx directly by viruses or bacteria. The most commonly observed infectious agents are the viruses. Group A beta hemolytic streptococci (GABHS) cases are observed in childhood (15–30%) and in the adult age group (5–15%). GABHS is the most commonly observed bacterial agent and it frequently leads to acute pharyngitis. Since the disease can lead to complications such as rheumatic fever, peritonsillar abscess, poststreptococcal glomerulonephritis,scarlet fever,etc., precise diagnosis and appropriate antibiotic treatment are required for preventing transmission and shortening the clinical course [8,9]. International Journal of Pediatric Otorhinolaryngology 74 (2010) 591–593 A R T I C L E I N F O Article history: Received 15 December 2009 Received in revised form 16 February 2010 Accepted 18 February 2010 Available online 15 March 2010 Keywords: Streptococcal infections Bacterial antigen Sensitivity and specificity A B S T R A C T 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. Materials and 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] casette test was applied and for culture, specimen was inoculated on 5% blood sheep agar and identifie 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 throatculture were evaluated.Rapid antigen detection sensitivity and specificity were found to be 64.6% and 96.79%, respectively. The positive predictive valu was 80.95% whereas negative predictive value was 92.82%. Kappa index was 0.91. When the results we 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%. Discussion: When bacterial infection is concerned to prevent unnecessary antibiotic use, rapid streptococcalantigen 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 pediatr age group. ß 2010 Elsevier Ireland Ltd. All rights reserved. * Corresponding author. Tel.: +90 216 578 00 00; fax: +90 535 970 01 28. E-mail addresses: yesimg@yeditepe.edu.tr (Y. Gurol), hakan@yeditepe.edu.tr (H. Akan), gizbirak@yeditepe.edu.tr (G. IzbI ˙ rak), ztazegun@yeditepe.edu.tr (Z.T.Tekkanat), sgunduz@yeditepe.edu.tr (T.S. Gunduz),ohayran@yeditepe.edu.tr (O. Hayran), gulden.yilmaz@yeditepe.edu.tr (G. Yilmaz). 1 Tel.: +90 216 578 00 00; fax: +90 555 828 17 16. 2 Tel.: +90 216 578 00 00; fax: +90 536 348 40 76. 3 Tel.: +90 216 578 00 00; fax: +90 505 7763034. 4 Tel.: +90 216 578 00 00; fax: +90 535 8884256. 5 Tel.: +90 216 578 00 00. 6 Tel.: +90 216 578 00 00; fax: +90 533 6253996. Contents lists available at ScienceDirect International Journal of Pediatric Otorhinolaryngology j o u r n a l h o m ep a g e : w w w . e l s e v i e r . c o m / l o c a t e / i j p o r l 0165-5876/$ – see front matter ß 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijporl.2010.02.020