Evaluation of a new rapid antigen detection kit for group A beta-hemolytic streptococci

Pediatr Emerg Care. 1998 Dec;14(6):396-8. doi: 10.1097/00006565-199812000-00004.


Objective: To evaluate the use of a new rapid antigen-detection kit for group A beta-hemolytic streptococcus and compare results with previously published studies.

Methods: Throat swabs were obtained prospectively from patients, aged one to 18 years, presenting to the emergency department, acute concerns clinic, and walk-in clinic of an urban tertiary care children's hospital. Throat swabs were first inoculated on a 5% sheep blood agar plate and then used for the streptococcus A optical immunoassay (OIA) kit. Results of both the throat culture and the rapid antigen-detection test were then compared.

Results: Two-hundred thirty-three patients were enrolled. Seventy-three patients had a positive culture and 63 patients had a positive OIA. Fifteen patients had a false negative result for the OIA kit and five patients had a false positive result. Test sensitivity was 79.5%, specificity was 96.9%, positive predictive value was 92.1%, and negative predictive value was 91.2%

Conclusion: Although previous studies have demonstrated OIA kit sensitivities as high as 98.9% and authors have, as a result, recommended that the performance of a backup throat culture for a negative OIA test is unnecessary, our results do not support this. A sensitivity of 79.5% is not sufficiently high to justify omission of a standard throat culture. Accordingly, all OIA tests that are negative should be confirmed by the performance of a throat culture.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Child
  • Child, Preschool
  • Evaluation Studies as Topic
  • Humans
  • Infant
  • Pharyngitis / diagnosis*
  • Pharyngitis / microbiology
  • Pharynx / microbiology
  • Prospective Studies
  • Reagent Kits, Diagnostic / standards*
  • Sensitivity and Specificity
  • Streptococcal Infections / diagnosis*
  • Streptococcus pyogenes*


  • Reagent Kits, Diagnostic