Ann Clin Microbiol.  2020 Sep;23(3):177-184. 10.5145/ACM.2020.23.3.1.

Performance Evaluation of STANDARD F Strep A Ag FIA for Diagnosis of Group A Streptococcal Pharyngitis

Affiliations
  • 1Department of Laboratory Medicine, Daewoo General Hospital, Geoje, Korea
  • 2Department of Pediatrics, Changwon Fatima Hospital, Changwon, Korea
  • 3Department of Laboratory Medicine, Gyeongsang National University Changwon Hospital, Changwon, Korea
  • 4Gyeongsang National University, Gyeongsang Institute of Health Sciences, Jinju, Korea

Abstract

Background
Pharyngitis is one of the most common conditions encountered in primary health care facilities. Accurate differentiation of group A streptococcus (GAS) infection from viral infection is difficult. The STANDARD F Strep A Ag FIA (SD BIOSENSOR, Korea) is a rapid antigen detection test (RADT) that has been recently developed for diagnosing GAS pharyngitis. In this study, we evaluated the diagnostic performance of the STANDARD F Strep A Ag FIA and compared the results between the RADT and conventional throat culture.
Methods
Throat swab samples were obtained from a total of 372 children presenting pharyngitis symptoms in five pediatric clinics in Changwon, Korea from July 2018 to October 2019. A comparative study between STANDARD F Strep A Ag FIA and Sofia Strep A FIA (Quidel, USA) was performed. Two throat swabs were taken simultaneously from each patient for RADT. The third throat swab was stored in a transport tube containing Stuart's transport medium for culture. Performance and kappa index of STANDARD F Strep A Ag FIA were evaluated.
Results
GAS infection was detected in 29.3% (109/372) patients, using the STANDARD F Strep A Ag FIA. The sensitivity, specificity, positive predictive value, and negative predictive value were 95.0%, 95.2%, 88.1%, and 98.1%, respectively. The STANDARD F Strep A Ag FIA showed an excellent concordance rate of 96.5% and a kappa value of 0.89 compared to Sofia Strep A FIA.
Conclusion
The STANDARD F Strep A Ag FIA demonstrated an excellent performance along with Sofia Strep A FIA for the diagnosis of GAS pharyngitis.

Keyword

Group A streptococcus; Pharyngitis; Rapid antigen test; Streptococcus pyogenes; Tonsillitis
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