[Comparative Study of Rapid Antigen Test Reagents for Group A Streptococcus spp.]

We compared rapid antigen detection kits widely used for the rapid diagnosis of group A streptococcal pharyngitis, evaluating their minimum detection sensitivity and operability in five levels. Five kits based on the immunochromatographic method were used: ImunoAce Strep A (Tauns), ImunoAce Strep A Neo (Tauns), Quick Navi-StrepA2 (Denka), Quick Vue Dipstick Strep A (SB Bioscience) and RapidTesta Strep A (SEKISUI MEDICAL). Thirteen strains were tested: 10 clinical isolates of Streptococcus pyogenes, 2 strains of Streptococcus dysgalactiae subsp. equisimilis (SDSE), and S. pyogenes ATCC 19615. All kits had the same or higher minimum detection sensitivity than previously reported. ImunoAce StrepA Neo had the highest detection sensitivity and the best overall evaluation among the group A streptococcal rapid antigen detection kits used in this study. The detection sensitivity of SDSE with group A polysaccharide antigen was comparable to that of S. pyogenes. Although culture tests are necessary to confirm the causative organism, SDSE may present with clinical symptoms similar to those of S. pyogenes, and detection with a rapid antigen detection kit may be of therapeutic value.