Group A Streptococci (GAS) are the main causative agents of bacterial pharyngitis, which require antibiotic therapy. Rapid diagnostic tests detecting GAS combined with Centor/McIsaac score enable accurate differential diagnosis (viral vs. bacterial) and prompt commencement of targeted treatment. The aim of this study was to assess the specificity, sensitivity, PPV and NPV of QuikRead go® Strep A (Orion Diagnostica Oy, Finland) recommended for the detection of GAS in pharyngeal swabs. Quick diagnostic test results were compared with physical examination findings, Centor/McIsaac score and results of reference testing (conventional microbial cultures). The study group of 96 participants consisted of 44 women (46%) and 52 men (54%); children aged 3-14 years constituted 46% of the patients. S. pyogenes were cultured from 43 of 96 pharyngeal swabs. Almost half of all positive samples (47%, n = 20) were collected from children aged 3 to 14 years. Positive GAS cultures were confirmed in 33% of patients with Centor/McIsaac score of 2 points, 48% of patients with score of 3, and 50% of patients with score of 4-5. Microbial cultures confirmed the positive results of QuikRead go® Strep A test in 83% of cases. Test specificity and sensitivity were calculated for the entire study group, which were 85% and 91%, respectively. The PPV of the test was 83% and its NPV was 92%. Using quick tests to detect GAS antigens appears a good alternative to conventional microbial diagnosis of strep throat, as it enables making a diagnosis and deciding on treatment plan in one appointment.
Keywords: Centor/McIsaac score; Rapid test QuikRead go® Strep A; Streptococcal pharyngitis; Streptococcus group A.