Beta-hemolytic group A streptococcus is the most common bacterial agent associated with pharyngitis. Rapid antigen detection tests should be used to diagnose pharyngitis (tonsillitis) due to Streptococcus pyogenes infection in order to make a sure diagnosis and to reduce usage of antibiotics.
Material and Methods A prospective study was conducted among 116 children (70 girls, 46 boys) aged 2–14 years (mean age 5.9 years, SD 2.6 years). Inclusive criteria to the study were: fever >38°C and sore throat. None of the children received antibiotics prior to testing. In all children, a rapid streptococcal test (Test Strep A®, SureScreen, UK) and conventional culture from the pharyngeal swabs were performed.
Results The rapid streptococcal test was positive in 16 patients (13.7%) while culture was positive in 14 (12%) patients. Among all positive rapid strep tests there were 12 true positive and 4 false positive. Among negative rapid strep tests 98 were true negative and 2 false negative.
The sensitivity of a rapid strep test was estimated as 86% and specifity as 96%.
The sensitivity (86%) was lower than shown in a product monograph (97%, 95% CI 91% to 99%) while the specifity (96%) was comparable with data shown in a description provide by producer (95%, 95% CI 92% to 97%).
Conclusions The examined rapid strep test (Test Strep A®) was less sensitive than it was suggested in the product monograph, but the sensitivity of 86% and specifity of 96% reached in ambulatory conditions are still high enough to find this test useful for clinical usage.