What is the recommended antibiotic, dose, and treatment duration for a 6-year-old child weighing 47 pounds with bacterial pharyngitis, characterized by a sore throat with pus on the tonsils and a productive cough?

Recommended Antibiotic for Bacterial Pharyngitis with Tonsillar Exudate in a 6-Year-Old

For this 6-year-old child (47 pounds/21 kg) with bacterial pharyngitis characterized by tonsillar pus, I recommend amoxicillin 420 mg (20 mg/kg/dose) twice daily for 10 days. 1

Diagnostic Confirmation Required First

Before prescribing antibiotics, you must confirm Group A Streptococcus (GAS) infection with either a rapid antigen detection test or throat culture, as clinical features alone cannot reliably distinguish bacterial from viral pharyngitis. 1 The presence of tonsillar exudate increases the likelihood of GAS, but testing remains essential since 15-20% of asymptomatic children are colonized with GAS. 1

Important caveat: The productive cough suggests a possible viral component or concurrent viral illness, as GAS pharyngitis typically does NOT present with prominent cough. 1 If cough is the predominant symptom, this may represent acute bronchitis (which is viral and does not require antibiotics) rather than bacterial pharyngitis. 1

Specific Dosing Regimen

Amoxicillin 420 mg (20 mg/kg/dose) orally twice daily for 10 days 1

• Weight-based calculation: 47 pounds = 21.4 kg × 20 mg/kg = 428 mg per dose (round to 420 mg for practical dosing)
• Alternative once-daily dosing: 840 mg (40 mg/kg) once daily is equally effective and may improve adherence 1
• The full 10-day course is absolutely essential to achieve maximal pharyngeal eradication and prevent acute rheumatic fever, even if symptoms resolve in 3-4 days 1, 2

Why Amoxicillin Over Penicillin V

While penicillin V remains the gold standard with zero documented resistance worldwide, amoxicillin is preferred in younger children due to better palatability and availability as suspension. 1 Both have identical efficacy for GAS pharyngitis. 1

Alternative Options if Penicillin Allergy

If non-anaphylactic penicillin allergy: First-generation cephalosporins are preferred

• Cephalexin 420 mg (20 mg/kg/dose) twice daily for 10 days 2
• Cross-reactivity risk is only 0.1% with non-immediate reactions 2

If immediate/anaphylactic penicillin allergy: Avoid all beta-lactams

• Clindamycin 147 mg (7 mg/kg/dose) three times daily for 10 days (maximum 300 mg/dose) 2
• Azithromycin 252 mg (12 mg/kg) once daily for 5 days (maximum 500 mg) 2, 3

Critical Treatment Considerations

Azithromycin is NOT first-line therapy despite its convenient 5-day course, because:

• Macrolide resistance among GAS is 5-8% in the United States (varies geographically) 2
• No data prove azithromycin prevents rheumatic fever 3
• Should be reserved for documented penicillin allergy 2

Third-generation cephalosporins (cefdinir, cefixime) are NOT recommended as first-line therapy because they unnecessarily broaden the antibiotic spectrum, increase cost, and promote resistance when narrow-spectrum agents like amoxicillin are effective. 1, 2

Addressing the Productive Cough

The productive cough component requires careful consideration:

• GAS pharyngitis typically does NOT cause prominent cough 1
• If cough is the predominant symptom, consider that this may be viral acute bronchitis superimposed on pharyngitis 1
• Acute bronchitis alone does NOT require antibiotics and is prescribed antibiotics inappropriately >70% of the time 1
• The presence of tonsillar pus strongly suggests bacterial pharyngitis, but the cough may represent a concurrent viral process 1

Symptomatic Management

For pain and fever control:

• Ibuprofen 10 mg/kg every 6-8 hours (more effective than acetaminophen) 2, 4
• Acetaminophen 15 mg/kg every 4-6 hours as alternative 2
• Never use aspirin in children due to Reye syndrome risk 2
• Medicated throat lozenges every 2 hours are effective 4

Corticosteroids are NOT recommended as they provide only minimal symptom reduction and are not worth the risks. 2

Common Pitfalls to Avoid

1. Do not shorten the antibiotic course below 10 days (except azithromycin's 5-day regimen), as this dramatically increases treatment failure rates and rheumatic fever risk 1, 2

2. Do not prescribe antibiotics without confirming GAS infection, as most pharyngitis is viral and antibiotics provide no benefit while causing harm through adverse effects and resistance 1

3. Do not assume all sore throats with exudate are bacterial - testing is mandatory since clinical criteria alone have poor predictive value 1

4. Do not treat the productive cough with antibiotics if it represents viral bronchitis - focus antibiotic therapy on the confirmed bacterial pharyngitis only 1

Goals of Treatment

The primary goals are preventing acute rheumatic fever and suppurative complications (peritonsillar abscess, cervical lymphadenitis), not just symptom relief. 1 Antibiotics shorten symptom duration by only 1-2 days but are critical for preventing serious complications. 1 Treatment can be safely delayed up to 9 days after symptom onset and still prevent rheumatic fever, so waiting for test results is appropriate. 2