Objective: Group A beta-hemolytic streptococci (GAS) are responsible for 20-40% of childhood pharyngitis which are mostly caused by viral agents. Early identification of the agent is crucial in preventing unnecessary use of antibiotics in viral infections and early initiation of antibiotic therapy and prevention of complications in GAS infections. Easy-touse rapid antigen tests with higher sensitive contribute significantly to early diagnosis and appropriate treatment. The aim of this study is to evaluate the efficacy of Bionexia rapid antigen test in detecting GAS in throat swab samples.

Material and Methods: A total of 1934 throat swab samples submitted to our laboratory with a pre-diagnosis of pharyngitis were assessed between 16 November 2015 and 15 February 2016. The samples were simultaneously cultured and tested by rapid Bionexia Strep-A Plus (BioMérieux, France). For identification, bacitracin sensitivity, PYR test and latex agglutination test in addition to Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) were used. The density of GAS growth in the culture was noted.

Results: A total of 1934 patients, 861 (44.5%) female and 1073 (55.5%) male cases were included in the study. The ages of the cases ranged between 1, and 75 years (mean: 8.7±6.7 years). Two hundred and fourteen (214; 11%) culture-positive, and 180 (9.3%) rapid antigen-positive samples were detected. Rapid antigen test positivity was significantly higher in denser culture growth (p=0.013). When compared with the corresponding rates culture positivity, Bionexia antigen test has 84.1% sensitivity, 100% specificity, 100% positive predictive, 98% negative predictive values and diagnostic accuracy rate was 98.2%.

Conclusion: Preference for a highly sensitive rapid antigen test can contribute significantly to the diagnosis and treatment of pharyngitis, appropriate use of antibiotics and prevention of the spread of resistance. Besides, the confirmation of negative rapid antigen test results by culture is essential to avoid misdiagnosis and insufficient treatment.