Evaluation of the direct detection of group A beta-hemolytic streptococcal antigen in a pediatric population: comparison with the traditional culture technique.

An evaluation of the Directigen Group A Strep Test (DGAST) in comparison with the traditional culture technique, was carried out on 1907 throat specimens, obtained from pediatric patients suspected of having a group A beta-hemolytic streptococcal pharyngitis. Of the 344 specimens positive by culture, 277 were DGAST positive (sensitivity, 81%). Of the 1563 specimens negative by culture, 1511 were DGAST negative (specificity, 97%). Nineteen isolates of non-group A beta-hemolytic streptococci were recovered, primarily group C, B and G. The DGAST is easy to perform, rapid and very specific, but lower sensitivity indicates that a back up traditional culture is still necessary, especially in pediatric patients.