Treatment for 5-Year-Old Male (25.4 lbs/11.5 kg) with Streptococcal Pharyngitis
Give amoxicillin 20 mg/kg/day divided every 12 hours (approximately 115 mg twice daily) for 10 days, which can be rounded to 125 mg twice daily using standard suspension formulations. 1, 2, 3
Weight-Based Dosing Calculation
- This child weighs 11.5 kg (25.4 lbs), which is well below the 40 kg threshold for adult dosing 2, 3
- For mild to moderate streptococcal pharyngitis in children under 40 kg, the Infectious Diseases Society of America recommends 20-25 mg/kg/day divided every 12 hours 1
- The FDA label specifies 25 mg/kg/day in divided doses every 12 hours for mild/moderate ear/nose/throat infections 3
- Using 25 mg/kg/day: 11.5 kg × 25 mg = 287.5 mg/day total, or approximately 145 mg per dose twice daily 3
- Round to 125 mg twice daily (250 mg/day total) using standard amoxicillin suspension, which is the closest practical dose 1, 2, 3
Why Amoxicillin Over Penicillin V
- Penicillin V remains the first-line agent recommended by guidelines, but amoxicillin is equally effective and preferred in young children due to superior palatability of the suspension 1, 2, 4
- The American Academy of Pediatrics notes that amoxicillin offers better taste acceptance, which improves adherence in pediatric patients 2
- Both agents have identical efficacy for Group A Streptococcus eradication 1, 4
Critical Duration and Administration Details
- Treatment must continue for the full 10 days regardless of symptom resolution to prevent acute rheumatic fever 1, 2, 3
- The Centers for Disease Control emphasizes that symptoms typically resolve in 3-4 days, but stopping early increases rheumatic fever risk 2
- Administer at the start of meals to minimize gastrointestinal intolerance 3
Alternative Regimens if Penicillin Allergy
- For non-anaphylactic penicillin allergy: first-generation cephalosporins (e.g., cephalexin) for 10 days 1, 2
- For immediate-type hypersensitivity to β-lactams: clindamycin 40 mg/kg/day divided into 3 doses (approximately 155 mg three times daily for this child) 1, 2
- Erythromycin 20-40 mg/kg/day is another option, though less palatable 1, 2
- Do NOT use first-generation cephalosporins in patients with immediate-type hypersensitivity reactions to penicillin 1
Common Pitfalls to Avoid
- Never prescribe adult 875 mg tablets or adult dosing for children under 40 kg, as this significantly exceeds recommended pediatric dosing 2
- Do not prescribe shorter courses (e.g., 5 days) despite some studies suggesting efficacy, as current guidelines do not endorse abbreviated therapy for routine use 1, 2
- Avoid sulfonamides and tetracyclines, which have high resistance rates and poor Group A Streptococcus eradication 2
- Do not stop antibiotics when the child feels better—the full 10-day course is essential to prevent rheumatic fever 2, 3
- Ensure proper suspension preparation: shake vigorously after reconstitution and before each dose 3