[Rapid antigen detection tests for group A streptococcus in children with pharyngitis]

Group A streptococcus (GAS) is the most frequently identified bacterium in children with acute pharyngitis. Clinical signs and symptoms cannot distinguish accurately between viral and GAS pharyngitis. Rapid antigen detection tests (RADTs) can identify GAS by an immunologic reaction within a few minutes. Compared to throat culture, most RADTs have a high specificity (around 95 %), allowing antibiotic prescribing on the basis of a positive RADT result. Similarly, the negative predictive value of RADTs seems sufficiently high (around 95 %) to ensure against the presence of GAS in case of a negative RADT result. Among several factors affecting RADT sensitivity, the training and expertise of the person performing the test and the quality of the throat swab specimen seem to be key determinants. Available evidence suggests that clinical prediction rules for the triage of children who should undergo GAS testing are not sufficiently accurate. Implementing RADTs into clinical practice has an important impact on antibiotic prescription rates, for a reduction of about 30 %. French guidelines that recommend using RADTs in all children above 3 years of age presenting with pharyngitis without backup culture of negative tests seem relevant in this context.