[Evaluation of a rapid technique for detecting the type A Streptococcus antigen (Test Pack Strep A)]

Aten Primaria. 1992 Apr;9(5):245-9.
[Article in Spanish]


Objective: To test a rapid technique of Antigen Detection (TAD) of Type A Betahemolitic Streptococci (BHSA) in Acute Tonsillitis (AT), comparing it with and using as a point of reference traditional Blood Agar Cultivation (BAC). Additionally, the use of Clinical Data as a method of supposed Diagnosis was studied.

Design: Prospective observational study. SITE. Health Primary Care (Maspalomas Health Centre).

Patients and other participants: 118 patients between the ages of 1 and 71 affected by AT.

Measurements and main results: There was a proportion of 13.56% BHSA in the AT of our sample, with a Confidence Interval (CI) of 95% (7.38-19.74) using the BAC; and 17.80% with a CI of 95% (10.90-24.70) using the TAD. The following values were obtained for the TAD: Sensitivity (S) of 93.75%, Specificity (Sp) of 94.12%, Positive Predictive Value (PPV) of 71.43% and Negative Predictive Value (NPV) of 98.9%. Of the clinical variables studied, only the presence/absence of Exudate and Adenopathies were linked to the presence of BHSA in the Cultivations (p less than 0.05 and p less than 0.01 respectively); with, however, inconclusive S, Sp, PPV and PNV values.

Conclusions: We found insufficient correlation between clinical findings and the presence of BHSA to consider it a valid method of supposed diagnosis. There was however a statistical link between the presence of Exudate and local Adenopathies, and a positive result in the cultivation. The TAD is shown to be a rapid method, easy to use, and highly reliable for the discovery of the presence of BHSA in AT.

Publication types

  • English Abstract

MeSH terms

  • Acute Disease
  • Adolescent
  • Adult
  • Aged
  • Antigens, Bacterial / analysis*
  • Child
  • Child, Preschool
  • Female
  • Humans
  • Infant
  • Male
  • Middle Aged
  • Pharyngitis / microbiology
  • Predictive Value of Tests
  • Prospective Studies
  • Sensitivity and Specificity
  • Streptococcal Infections / diagnosis
  • Streptococcal Infections / microbiology*
  • Streptococcus pyogenes / immunology*
  • Time Factors
  • Tonsillitis / microbiology


  • Antigens, Bacterial