Experts from the American Academy of Pediatrics (AAP) recommend that if a rapid test is negative for group A streptococcus antigen, a microbiological examination of the throat smear in patients suspected of pharyngitis caused by Streptococcus pyogenes is possible, but these recommendations complicate the decision the need for antibiotic therapy by a doctor during a visit without confirmation of the bacterial etiology of the disease. At the same time, it is believed that the use of an additional rapid test instead of microbiological research contributes to faster confirmation of the diagnosis. To compare different methods, a study was carried out which compared the sensitivity of a single rapid test, two consecutive rapid tests and a rapid test followed by a microbiological study of the material. In children suspected of pharyngitis caused by S. pyogenes, two throat swabs were taken, each of which was used for microbiological examination and rapid diagnosis using the OSOM Ultra Strep A test. The gold standard was considered to be the identification of S. pyogenes on at least one of the two sections.

Of the 887 patients with an acute pharyngitis clinic, 210 (23.7%) had a pathogen in the swabs. The sensitivity of a single rapid test and two consecutive rapid tests was 87.6% (95% confidence interval (CI): 83.2% -92.1%) and 91.4% (95% CI: 87.6% -92.1%), respectively. The sensitivity of the rapid test followed by a microbiological examination of the material is 95.7% (95% CI: 93.0% -98.5%), which considerably exceeds the first two methods.

However, when examining 158 children with specific symptoms of S. pyogenes infection (enlarged cervical lymph nodes, scarlet rash or purulent follicles on the surface of the tonsils), the sensitivity of all the methods increased and the differences between the methods ceased to be statistically significant.. None of the methods significantly exceeded the sensitivity threshold of 95%.

Thus, the rapid diagnostic method with double microbiological examination of the material for the detection of S. pyogenes in children with pharyngitis, proposed by the American Academy of Pediatrics, has been found to be more sensitive than the methods compared. However, the method of two consecutive rapid tests can be used in practice with an informed choice of patients with appropriate clinical symptoms.