Diagnosis of group A streptococcal pharyngitis in the paediatric emergency department using a fluorescence-based RADT: predicted impact on antibiotic prescription.

ABSTRACT

Introduction. Using rapid antigen diagnostic tests (RADTs) in clinical practice has shown excellent specificity but often has diminished sensitivity.Gap Statement. Local data for evaluating the diagnostic performance of a new fluorescence-based RADT and its influence on the antibiotic prescription rate are not available.Aim. To evaluate the accuracy of fluorescent immunoassay (FIA)-RADTs for diagnosing group A streptococcal (GAS) pharyngitis among children and its estimated effect as a point of care test (POCT) on the antibiotic prescription rate at the paediatric emergency department.Methodology. A prospective study was conducted, comprising children 3 to 14 years old presenting with pharyngitis. Throat swab culture and FIA-RADTs were performed on all samples. Conventional PCR was performed on the discordant samples.Results. A total of 246 children were included in this study. The sensitivity, specificity, and positive and negative predictive values of the FIA-RADT, based on culture results and PCR detection combined, were 95.6, 96.8, 94.6 and 97.4 %, respectively. Antibiotics have been prescribed to 162 (65.9 %) children; however, if FIA-RADTs had been added in the clinical practice as a POCT, only 92 (37.4 %) children would have received antibiotics in total. Additionally, implementation of FIA-RADTs would significantly reduce the antibiotic prescription rate from 48.8 and 60.6 % to 9.5 and 31.9 % among patients with clinical scores of 2 and 3, respectively.Conclusion. The new FIA-RADT is simple, prompt and reliable. It is helpful in clinical settings and may be used to reduce antibiotic overprescription, especially for children who have a low risk for GAS pharyngitis, according to the clinical score.