Latex agglutination tests for rapid identification of group A streptococci directly from throat swabs

J Pediatr. 1984 Nov;105(5):702-5. doi: 10.1016/s0022-3476(84)80286-3.

Abstract

A comparison of the accuracy and practicality of two new latex agglutination tests for the rapid identification of group A beta-hemolytic streptococci directly from throat swabs was performed in a busy pediatric office. The Directigen Group A Strep Test kit had a sensitivity of 84%, specificity 99%, positive predictive value 99%, and negative predictive value 93% when compared with blood agar cultures. The Culturette Brand 10-Minute Group A Strep ID Kit had a sensitivity of 83%, a specificity 99%, positive predictive value 97%, and negative predictive value 93% when compared with blood agar cultures. When cultures with less than 10 colonies of group A beta-hemolytic streptococci per plate were not considered positive, both rapid tests had a sensitivity of 95%. The Culturette Brand test required considerably less time, equipment, supplies, and skill than the Directigen test. Only the Culturette Brand test appeared to be practical for routine use in a pediatrician's office. Further investigations of the accuracy of both of these rapid tests need to be performed before either is accepted as a substitute for the throat culture.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Blood / microbiology
  • Child
  • Child, Preschool
  • Humans
  • Latex Fixation Tests / instrumentation
  • Latex Fixation Tests / methods*
  • Pharyngitis / microbiology*
  • Pharynx / microbiology*
  • Streptococcal Infections / diagnosis
  • Streptococcus pyogenes* / growth & development
  • Streptococcus pyogenes* / immunology