AN OPTICAL IMMUNOASSAY FOR THE DIRECT-DETECTION OF GROUP-A STREP ANTIGEN

We used all optical immunoassay (Strep A OIA, Biostar, Boulder, Colo) to evaluate 483 throat-swab specimens for the presence of group A stre ptococcal (GAS) antigen. We compared the results with those achieved b y a rapid latex test (PathoDx, Diagnostic Products, Los Angeles), with culture by standard methods, and with culture in an enriched Todd-Hew itt broth. Although the specificities of the two rapid assays were sim ilar (98%), the sensitivity of the OIA technique (95%) exceeded that o f the latex method (43%), and was felt to be as sensitive as culture. Strep A OIA appears to be a reliable, easily interpretable method for detection of GAS antigen directly from clinical specimens.