Enzyme fluorescence procedure for rapid diagnosis of streptococcal pharyngitis

Abstract

Recently there has been a proliferation of rapid diagnostic tests for group A/3-hemolytic streptococcal pharyngitis. 1,2 These tests have the potential to provide rapid diagnosis of GABHS pharyngitis and thus facilitate the prompt initiation of appropriate antibiotic therapy. This in turn can shorten the duration of the clinical illness and the period of infectivity, expediting a patient's return to school or day care as well as a parent's return to work? These tests also have the potential to exclude GABHS pharyngitis rapidly and thereby preclude initiation of unnecessary antibiotic therapy in patients with nonstreptococcal pharyngitis? Although several different procedures are available, the few published reports comparing these new rapid diagnostic tests with conventional blood agar plate cultures have dealt almost exclusively with two latex agglutination kits: the Directigen Group A Strep Test Kit (Hynson, Westcott, and Dunning, Baltimore) and the Culturette Brand TenMinute Group A Strep ID Kit (Marion Scientific, Kansas City, Mo. )Y ~ Little or no published data are available regarding the accuracy of the other latex agglutination kits, the enzyme immunoassay procedure, or the enzyme fluorescence procedure. The Strep-A-Fluor test (BioSpec Inc, Dublin, Calif.) is a new enzyme fluorescence procedure for the rapid diagnosis of GABHS pharyngitis. This test is based on the observation, first made by Godsey et al. in 1981, that GABHS produce a specific aminopeptidase that hydrolyzes the enzyme L-pyrrolidonyl-/3-naphthylamide. In the Strep-A-Fluor procedure, a throat swab is applied to a filter paper strip that has been impregnated with a synthetic, nonfluorescent substrate similar to Pyr. If GABHS are present on the swab, the aminopeptidase produced by these