The Lyra Direct Strep Assay is a Real-Time PCR in vitro diagnostic test for the rapid and qualitative detection and differentiation of Group A β-hemolytic Streptococcus (Streptococcus pyogenes) and pyogenic Group C and G β-hemolytic Streptococcus (Streptococcus dysgalactiae, Streptococcus equi, Streptococcus canis) nucleic acids isolated from throat swab specimens obtained from symptomatic patients. Streptococcal pharyngitis, or "strep throat", is a common bacterial infection found in childhood. Group A Streptococci are responsible for the majority of Streptococcal pharyngitis cases although other species, such as S. dysgalatiae,S. equi and S. canis (pyogenic Group C and G β-hemolytic Streptococcus) may also cause disease. Traditionally, Streptococci have been classified by the production of hemolysis on blood agar and by the use of Lancefield group antigens; however, culture hemolysis can be imprecise due to number of factors (operator experience, incubation conditions of the culture, types of hemolysin produced by the organism, etc.) and the Lancefield group antigen does not correlate with the species. Additionally, culture results may take 2 to 3 days such that physicians treat patients presumptively while awaiting culture results or withhold antibiotic therapy until the causative organism is confirmed with culture. Fortunately, molecular taxonomic studies have improved classification and time to results.
The Lyra Direct Strep multiplex real-time PCR reaction is carried out under optimized conditions in a single tube generating amplicons for Group A, C & G and the Process Control (PRC). It provides test results in less than 70 minutes for the identification of Group A and Group C or G (the assay does not differentiate between pyogenic Groups C and G β-hemolytic Streptococcus). Specific primers and fluorescent-labeled probes that hybridize to conserved regions in the genomes of the group A Streptococci, pyogenic group C and G Streptococci and the PRC allow for a highly specific, highly sensitive assay. The Lyra Direct Strep Assay has one-step reagent set-up and a three-step sample prep and is available for use on the Applied Biosystems® 7500 series of instruments.