A 7-year-old boy presents with fever (39.2°C), sore throat, and absence of cough. On examination, the structure marked **B** is noted along with tender anterior cervical lymphadenopathy. Using the Centor/McISAAC criteria, what is the most appropriate next step in management?

Explanation

## Why "Perform rapid antigen detection test (RADT); treat if positive" is right This 7-year-old scores 4 points on the Centor/McISAAC criteria: absence of cough (1), tonsillar exudate marked **B** (1), tender anterior cervical lymphadenopathy (1), fever >38°C (1), and age 3-14 years (1). A score of 4 falls in the "consider RADT + treat if positive" category per modified McISAAC guidelines. While some high-risk score protocols allow empiric treatment, the standard evidence-based approach in pediatrics is to confirm with RADT (sensitivity 80-90%, specificity 95-100%) before antibiotics. This balances diagnostic accuracy with avoiding unnecessary antibiotic exposure. If RADT is negative in a child, throat culture should follow to rule out false negatives. ## Why each distractor is wrong - **Treat empirically with penicillin V for 10 days without further testing**: Although a score of 4 is "high likelihood," current pediatric guidelines (Nelson, AAP) recommend RADT confirmation before treatment in most settings, reserving empiric treatment for scores of 5 or in high-risk populations with poor follow-up. Empiric treatment without testing increases unnecessary antibiotic use. - **Perform throat culture immediately and defer treatment until antibiotics results**: Throat culture is the gold standard but takes 24-48 hours. It is not the immediate next step for a score of 4; RADT is faster and has high specificity. Culture is reserved for RADT-negative cases in children to rule out false negatives. - **Observe without testing or treatment as viral pharyngitis is more likely**: A Centor score of 4 indicates high likelihood of Group A Streptococcus (GAS) pharyngitis, not viral. Withholding testing and treatment risks missing the opportunity to prevent acute rheumatic fever (must treat within 9 days of symptom onset). **High-Yield:** Centor/McISAAC score 4–5 in children warrants RADT ± empiric treatment; score 0–1 requires no testing; score 2–3 requires RADT before treatment. White-yellow tonsillar exudate (**B**) is a key criterion but cannot distinguish bacterial from viral alone—testing is essential. [cite: Dhingra ENT 7e; Nelson 21e Ch 410]