Augmentin Dosing for 18.1 kg Child with Strep A and Cervical Lymphadenopathy
For this 18.1 kg child with confirmed Group A Streptococcus infection and cervical lymphadenopathy, prescribe Augmentin at 90 mg/kg/day of the amoxicillin component divided into 2 doses (approximately 815 mg twice daily), given for 10 days. 1
Weight-Based Dose Calculation
- For an 18.1 kg child: 18.1 kg × 90 mg/kg/day = 1,629 mg/day total, divided into 815 mg twice daily 1
- Using standard suspension formulations: This translates to approximately 16.3 mL of 250 mg/5 mL suspension twice daily, or 8.2 mL of 400 mg/5 mL suspension twice daily 1
- The maximum daily dose should not exceed 4,000 mg of amoxicillin component per day 1
Rationale for High-Dose Regimen
- Group A Streptococcal infections require 50-75 mg/kg/day according to standard guidelines, but given the recent influenza infection and cervical lymphadenopathy suggesting more severe or complicated infection, the higher 90 mg/kg/day dosing is warranted 1
- The 90 mg/kg/day regimen provides superior coverage against potentially resistant organisms and ensures adequate tissue penetration for lymphadenopathy 1, 2
- Augmentin (amoxicillin-clavulanate) is specifically indicated over plain amoxicillin when there is concern for β-lactamase-producing organisms, which may be more likely after recent viral illness 1, 3
Treatment Duration and Monitoring
- Complete a full 10-day course to prevent acute rheumatic fever and ensure complete eradication of Group A Streptococcus 4, 1
- The FDA label specifically mandates at least 10 days of treatment for any Streptococcus pyogenes infection 4
- Clinical improvement should occur within 48-72 hours; if no improvement is seen, reevaluation is necessary 1
- The child becomes non-contagious after 24 hours of appropriate antibiotic therapy 1
Administration Instructions
- Administer at the start of meals to minimize gastrointestinal intolerance 4
- Shake oral suspension well before each use 4
- Refrigeration is preferable but not required; discard any unused suspension after 14 days 4
Critical Considerations
Common pitfall to avoid: Do not underdose at 45 mg/kg/day, which is inadequate for complicated streptococcal infections with lymphadenopathy. The recent influenza infection may have compromised local immune defenses, making higher dosing essential 1, 2
Alternative for penicillin allergy: If the child has a non-anaphylactic penicillin allergy, consider cephalexin or cefdinir; for Type I hypersensitivity, use clindamycin at 10-20 mg/kg/day divided into 3 doses 1