What is the best alternative antibiotic for a 1 year 2 month old child with acute pharyngitis who experienced gastrointestinal side effects from amoxicillin (amoxicillin clavulanic acid)?

Best Alternative Antibiotic for Acute Pharyngitis with Amoxicillin-Clavulanate Intolerance

Switch to oral amoxicillin alone at 90 mg/kg/day divided into 2 doses for 10 days, as the gastrointestinal side effects were most likely caused by the clavulanic acid component rather than the amoxicillin itself. 1

Rationale for Amoxicillin Alone

• The loose stools experienced by this child were almost certainly due to the clavulanic acid component, not the amoxicillin, as clavulanic acid is well-documented to cause significantly higher rates of gastrointestinal adverse events (particularly diarrhea) compared to amoxicillin alone 2
• In comparative studies, amoxicillin-clavulanate caused diarrhea/loose stools in 12.7-29% of children versus only 2-6.4% with amoxicillin alone or other antibiotics 3
• Amoxicillin remains the treatment of choice for Group A Streptococcal pharyngitis due to its proven efficacy, safety, narrow spectrum, and low cost 1, 4
• Penicillin-resistant Group A Streptococcus has never been documented, making amoxicillin reliably effective 1, 4, 5

Alternative Options If Amoxicillin Alone Fails or Is Not Tolerated

If the child develops similar gastrointestinal symptoms with amoxicillin alone (unlikely), consider the following alternatives in order:

First-Line Alternatives (Narrow Spectrum Cephalosporins)

• Cephalexin 20 mg/kg per dose twice daily for 10 days 5
• Cefadroxil 30 mg/kg once daily for 10 days 1, 5
• These narrow-spectrum cephalosporins are preferred over broad-spectrum agents and have lower rates of gastrointestinal side effects than amoxicillin-clavulanate 1, 2
• Avoid in cases of immediate (anaphylactic-type) hypersensitivity to penicillin, as up to 10% of penicillin-allergic patients are also allergic to cephalosporins 1

Second-Line Alternatives (For True Penicillin Allergy)

• Azithromycin 12 mg/kg once daily (maximum 500 mg) for 5 days 1, 5, 3

• This higher dose (12 mg/kg/day for 5 days = 60 mg/kg total) provides better Group A Streptococcal eradication than the standard 10 mg/kg dose 6

• Macrolide resistance rates among pharyngeal isolates in the United States are approximately 5-8%, which is a consideration 1

• Gastrointestinal side effects with azithromycin (6-18%) are generally lower than with amoxicillin-clavulanate but higher than amoxicillin alone 3, 7

• Clindamycin 7 mg/kg per dose three times daily (maximum 300 mg/dose) for 10 days 1, 5

• Clindamycin resistance among Group A Streptococcus isolates in the United States is approximately 1%, making this a highly effective alternative 1, 5

Monitoring Parameters

Clinical Response Assessment:

• Expect clinical improvement within 48-72 hours of starting appropriate antibiotic therapy 1, 4
• Monitor for resolution of fever, throat pain, and difficulty swallowing 4
• If symptoms persist or worsen beyond 48-72 hours, further investigation is warranted 1, 4

Gastrointestinal Tolerance:

• Monitor stool frequency and consistency during the first 3-5 days of therapy
• If loose stools recur with amoxicillin alone, this would be unusual and should prompt consideration of alternative diagnoses or switch to a cephalosporin 2

Hydration Status:

• Monitor for signs of dehydration, particularly if any gastrointestinal symptoms persist 4
• Ensure adequate fluid intake throughout treatment course

Fever Monitoring:

• High persistent fever (>104°F or 40°C) or fever lasting beyond 48-72 hours of antibiotic treatment requires re-evaluation 4

Adherence to Full Course:

• Complete the full 10-day course even when symptoms improve to achieve maximal pharyngeal eradication and prevent acute rheumatic fever 1, 4, 5
• The exception is azithromycin, which requires only 5 days due to its prolonged tissue half-life 5, 3

Common Pitfalls to Avoid

• Do not avoid all amoxicillin formulations based on intolerance to amoxicillin-clavulanate, as the clavulanic acid is the likely culprit for gastrointestinal side effects 2
• Do not use trimethoprim-sulfamethoxazole, sulfonamides, tetracyclines, or older fluoroquinolones as they do not eradicate Group A Streptococcus or have high resistance rates 1, 5
• Do not use aspirin for fever or pain control in children due to risk of Reye syndrome 1, 4, 5
• Do not routinely test or treat asymptomatic household contacts unless they develop symptoms 1

Adjunctive Therapy

• Acetaminophen or ibuprofen for fever and throat pain control 1, 4, 5
• Corticosteroids are not recommended for pharyngitis in children 1, 5