Multicenter clinical evaluation of the automated ARIES ® Group A Strep PCR Assay from throat swabs.

Group A Streptococcus (GAS) is one of the leading causes of bacterial pharyngitis. Early GAS diagnosis is critical for appropriate antibiotic administration that reduces the risk of GAS sequela and limits spread of the infection. The ARIES® Group A Strep (GAS) Assay (Luminex, Austin, TX) is a fully automated PCR assay for direct detection of GAS in throat swab specimens in less than two hours with minimum hands-on time. This multicenter prospective study evaluated the clinical performance of the ARIES® GAS Assay as compared to Streptococcus pyogenes culture. Subjects with symptoms consistent with pharyngitis were enrolled across four sites in the United States and a throat swab in liquid Amies medium was obtained. ARIES® and reference testing was performed within 72 and 48 hours after sample collection, respectively. Of 623 throat-swab specimens from patients with pharyngitis (93.6% <18-years-old, 54.3% female), the reference method yielded valid results for 618 specimens. Reference and ARIES® assay testing showed GAS positive results for 160 (25.9%) and 166 specimens (26.9%), respectively. As compared to the reference method, ARIES® assay sensitivity was 97.5% (95% CI:93.7‒99.0%), specificity was 97.8% (95% CI:96.0‒98.8%), positive predictive value was 94.0% (95% CI:89.3‒96.7%), and negative predictive value was 99.1% (95% CI:97.7‒99.7%). There were ten false positive and four false negative detections with the ARIES® assay. Discrepant analysis with bidirectional sequencing yielded concordant results with the ARIES® assay for nine of 14 discordant samples. The ARIES® assay had high sensitivity and specificity for qualitative detection of Group A Streptococcus from patients with pharyngitis.