Evaluation of the Strep-A-Chek technique for presumptive identification of group A beta-hemolytic streptococci and group D enterococci

Abstract

Strep-A-Check (E-Y Laboratories, San Mateo, CA) is a 15-min chromogenic test for a species-specific aminopeptidase that could replace testing bacitracin susceptibility for presumptive identification of group A streptococci as well as 6.5% NaCl agar tolerance for presumptive identification of enterococcal streptococci, with a time savings of 24 hr. Recent clinical streptococcal isolates (n = 341), identified by conventional biochemical and serologic techniques, were used to evaluate the 15-min Strep-A-Chek test. Among the beta-hemolytic streptococci (176 group A, 43 group B, 8 group C, 9 group F, and 9 group G), Strep-A-Chek was 100% accurate. Among the non-beta-hemolytic streptococci, 100% of 52 group D enterococci, 100% of 30 viridans streptococci, and 100% of 14 group D nonenterococci were correctly identified by Strep-A-Chek. Strep-A-Chek is an extremely rapid and reliable test for presumptive identification of group A and enterococcal streptococci.