Rapid identification of group A streptococci by the Strep-A-Fluor system.
Group A streptococci can be rapidly identified by the Strep-A-Fluor system (Bio-Spec Inc., Dublin, CA), which uses a specific aminopeptidase to hydrolize L-pyrrolidonyl-beta-naphthylamide. In pure subcultured colonies and in isolated colonies from primary culture plates, the Strep-A-Fluor system had 100% sensitivity and 100% specificity compared with the results of Streptex latex agglutination (Wellcome Research Laboratories, Research Triangle Park, NC). However, in mixed culture from primary culture plates, the sensitivity and specificity were 73% and 95%, respectively. Furthermore, in a routine laboratory setting, the sensitivity was only 91% both from pure subcultured colonies and from isolated colonies from primary culture plates. Contamination with organism other than group A streptococci that are capable of hydrolyzing L-pyrrolidonyl-beta-naphthylamide may explain the low specificity in mixed culture. Deterioration of the buffer reagent due to prolonged use may account for the low sensitivity in a routine laboratory setting.
D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans; D007841:Latex Fixation Tests; D010612:Pharyngitis / Q000175:diagnosis; D011760:Pyrrolidinones / Q000378:metabolism; D011933:Reagent Kits, Diagnostic; D013290:Streptococcal Infections / Q000175:diagnosis*; D013297:Streptococcus pyogenes / Q000145:classification* / Q000378:metabolism
D011760:Pyrrolidinones; D011933:Reagent Kits, Diagnostic; C034099:pyrrolidonyl-beta-naphthylamide