Alternative Antibiotic for 1-Year-Old with Pharyngitis and Moxclav-Induced Diarrhea
Switch to oral amoxicillin (without clavulanate) at 90 mg/kg/day divided into 2 doses for 10 days, as the clavulanate component in Moxclav is the primary cause of gastrointestinal side effects including loose stools. 1
Understanding the Problem
The loose stools are almost certainly caused by the clavulanate component of amoxicillin-clavulanate (Moxclav), not the amoxicillin itself. Clavulanate significantly increases gastrointestinal adverse events, particularly diarrhea, compared to amoxicillin alone. 2 This is a well-documented side effect that does not represent a true allergy or contraindication to beta-lactam antibiotics.
Primary Recommendation: Switch to Amoxicillin Alone
- For a 1-year-old with Group A Streptococcal (GAS) pharyngitis, amoxicillin 90 mg/kg/day divided into 2 doses (or 45 mg/kg/day in 3 doses) for 10 days is the treatment of choice. 1
- Amoxicillin is preferred over penicillin V in young children due to better palatability and acceptance of the suspension. 1
- This maintains the narrow spectrum of activity, proven efficacy, safety profile, and low cost that make penicillins first-line therapy. 1
- Penicillin-resistant GAS has never been documented. 1
Alternative Options If Amoxicillin Cannot Be Used
First-Generation Cephalosporins (If No True Penicillin Allergy)
- Cephalexin 20 mg/kg per dose twice daily for 10 days or cefadroxil 30 mg/kg once daily for 10 days are appropriate alternatives. 3, 4
- These should only be avoided if there is a history of immediate hypersensitivity (anaphylaxis, angioedema, urticaria) to penicillin, as cross-reactivity occurs in up to 10% of such cases. 3, 4
- Since the child only experienced loose stools (not an allergic reaction), first-generation cephalosporins are safe to use. 3
- Research shows cefaclor has significantly lower rates of gastrointestinal adverse events compared to amoxicillin-clavulanate. 2
Macrolides (If Beta-Lactams Cannot Be Used)
Azithromycin 12 mg/kg once daily (maximum 500 mg) for 5 days is FDA-approved for pharyngitis/tonsillitis in children aged 2 years and above. 5
For a 1-year-old, azithromycin dosing would be 10 mg/kg on day 1, followed by 5 mg/kg/day on days 2-5. 1, 5
However, azithromycin should be reserved for true penicillin allergy, as macrolide resistance among GAS ranges from 5-8% in the United States. 3, 6
The FDA label specifically notes that penicillin is the usual drug of choice, and azithromycin is "often effective" but some strains are resistant. 5
Clarithromycin 15 mg/kg/day divided into 2 doses for 10 days is another macrolide option. 1
Clindamycin (For Severe Penicillin Allergy)
- Clindamycin 7 mg/kg per dose three times daily (maximum 300 mg/dose) for 10 days is highly effective. 3, 4
- Clindamycin has approximately 1% resistance among GAS isolates in the United States. 3
- It is particularly effective in chronic carriers and treatment failures. 3, 4
Critical Treatment Duration
- All antibiotics except azithromycin require a full 10-day course to achieve maximal pharyngeal eradication of GAS and prevent acute rheumatic fever. 1, 3
- Azithromycin requires only 5 days due to its prolonged tissue half-life. 1, 3
- Shortening the course by even a few days results in appreciable increases in treatment failure rates. 3
Important Caveats
- Do not use trimethoprim-sulfamethoxazole or sulfonamides, as they do not eradicate GAS from the pharynx. 1
- Do not use tetracyclines due to high prevalence of resistant strains. 1
- Do not use older fluoroquinolones (ciprofloxacin) as they have limited activity against GAS. 1
- Routine post-treatment throat cultures are not recommended for asymptomatic patients who complete therapy. 1, 3