Background There isn’t universal agreement regarding streptococcal pharyngitis, still considered rare below age 3 years.

Aims To study prevalence variations by age, season and clinical data. To test Centor and McIsaac scores and seek a better predictive model.

Methods We retrospectively reviewed all clinical records of the patients seen in our hospital in 2011 selecting those in whom a throat swab for rapid antigen detection test or throat culture was collected to study prevalence and those with pharyngitis or scarlet fever diagnosis without throat swab to test score application effect on antibiotic prescription.

Results GABHS prevalence: 28.3%, 1303 children included (aged 58 days-13 years), without seasonality:

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Abstract PO-027 Figure 1

Centor and McIsaac scores didn’t differ between those with and without GABHS The best puctuation system we found, by logistic regression analysis, can predict GABHS with ROC 0.738 (95% CI: 0.702–0.772) combining age ≥3 years, scarlatiniform rash, palatal petechiae, lower temperature and absence of cough, but is complex. Its use without throat swab would’ve decreased antibiotic prescription at most 11–12% in this setting.

Conclusions GABHS seems more prevalent below age 3 years than commonly considered. Seasonality isn’t clear. Neither Centor nor McIsaac score was valid here, but finding a simple and better predictive model is complicated.