RAPID ANTIGEN TESTING FOR GROUP-A STREPTOCOCCUS BY DNA-PROBE

The Gen-probe group A Streptococcus direct test (GASD), a nucleic acid probe assay for detecting GAS from throat swabs, has recently been de veloped. The test uses an acridium ester-labeled DNA probe which is co mplementary to the rRNA of Streptococcus pyogenes. In this study, 318 single culturette throat swabs were tested by this method using cultur e as a ''gold standard.'' After plating onto trypticase soy agar plate s with 5% sheep blood, swabs were stored at 4 degrees C for no more th an 72 h before the probe assay mas performed. Our patient population c onsisted of symptomatic outpatients seen in the Memorial Hospital Emer gency Department and in the Family Care Center. After discrepancy test ing, sensitivity, specificity, and positive and negative predictive va lues were 91.4%, 97%, 91.4%, and 97%. The GASD is a rapid, easy-to-per form method for batch screening for streptococcal pharyngitis.