What is the recommended antibiotic, dose, frequency, and duration for a 6-year-old male patient weighing 47 pounds with a productive cough, nasal drainage, and purulent tonsils, who had a fever for 2 days that has since resolved, and has no known allergies?

Antibiotic Treatment for Pediatric Pharyngotonsillitis with Purulent Exudate

For this 6-year-old male (47 lbs/21.4 kg) with purulent tonsillar exudate, prescribe amoxicillin 50 mg/kg/day divided into two doses (approximately 535 mg twice daily) for 10 days. 1, 2

Specific Prescription Details

Weight-based calculation:

• Patient weight: 47 lbs = 21.4 kg
• Dose: 50 mg/kg/day = 1,070 mg total daily dose
• Divided into 2 doses = 535 mg twice daily 1, 2

Practical formulation:

• Using 400 mg/5 mL suspension: Give 6.7 mL (approximately 7 mL) twice daily 2
• Alternative using 250 mg/5 mL suspension: Give 10.7 mL (approximately 11 mL) twice daily 2

Duration: 10 days 1, 2

Clinical Rationale

This presentation is most consistent with Group A Streptococcal pharyngitis given the purulent tonsillar exudate, which requires the full 10-day course to prevent rheumatic fever and achieve bacterial eradication. 1, 2 The productive cough and nasal drainage suggest a concurrent viral upper respiratory infection, which is common with streptococcal pharyngitis. 3, 4

The Infectious Diseases Society of America recommends 50-75 mg/kg/day for streptococcal infections, with the lower end of this range (50 mg/kg/day) being appropriate for uncomplicated pharyngitis. 1, 2 This dosing provides adequate coverage against Streptococcus pyogenes while minimizing adverse effects. 2

Monitoring and Follow-up

Expected clinical response:

• The child should become non-contagious after 24 hours of antibiotic therapy 2
• Clinical improvement should be evident within 48-72 hours 1, 5
• If no improvement occurs within 48-72 hours, reevaluation is necessary to consider treatment failure or alternative diagnoses 1, 5

Critical instruction to parents:

• Complete the full 10-day course even if symptoms resolve earlier, as incomplete treatment increases risk of rheumatic fever and bacterial resistance 1, 2

Important Clinical Considerations

Why not higher-dose amoxicillin? The 90 mg/kg/day regimen is reserved for pneumonia or areas with high penicillin-resistant Streptococcus pneumoniae prevalence, not for streptococcal pharyngitis. 1, 5 Group A Streptococcus remains universally susceptible to penicillins. 2

Why 10 days instead of shorter duration? Unlike pneumonia where 5-7 days may suffice, streptococcal pharyngitis requires 10 days to prevent rheumatic fever and achieve bacteriologic cure. 1, 2 This is a critical distinction that cannot be shortened.

Common pitfall to avoid: Do not prescribe amoxicillin-clavulanate (Augmentin) for uncomplicated streptococcal pharyngitis, as the clavulanate component is unnecessary and increases cost and gastrointestinal side effects without added benefit. 1, 2 Reserve amoxicillin-clavulanate for pneumonia or when beta-lactamase-producing organisms are suspected. 1, 4