What is the recommended antibiotic and dosing for a 3-year-old child weighing 30 pounds with acute sinusitis?

Antibiotic Selection and Dosing for a 3-Year-Old with Acute Bacterial Sinusitis

For a 3-year-old child weighing 30 pounds (13.6 kg) with acute bacterial sinusitis, high-dose amoxicillin-clavulanate at 90 mg/kg/day of the amoxicillin component (1,224 mg/day divided into 2 doses, or approximately 612 mg twice daily) for 10-14 days is the recommended first-line treatment. 1, 2, 3

Why High-Dose Amoxicillin-Clavulanate for This Patient

This 3-year-old meets multiple high-risk criteria that mandate high-dose therapy rather than standard-dose amoxicillin:

• Age <2 years is a risk factor, and this child is only 3 years old 1, 3
• Likely daycare attendance at this age increases risk of resistant organisms 1, 3
• The clavulanate component provides essential coverage against β-lactamase-producing Haemophilus influenzae (10-42% resistance) and Moraxella catarrhalis (nearly 100% β-lactamase positive) 3, 4
• High-dose amoxicillin component (90 mg/kg/day) ensures adequate coverage against penicillin-resistant Streptococcus pneumoniae, which accounts for 30-66% of pediatric sinusitis cases 3, 4, 5

Specific Dosing Calculation

• Weight: 30 pounds = 13.6 kg
• Dose: 90 mg/kg/day of amoxicillin component = 1,224 mg/day
• Divided into 2 doses = 612 mg twice daily 1, 2, 3
• Duration: 10-14 days 1, 3

Alternative First-Line Option (If Standard Therapy Appropriate)

If this child did NOT have high-risk features, standard-dose amoxicillin would be acceptable:

• Standard dose: 45 mg/kg/day in 2 divided doses = 306 mg twice daily 1, 3
• However, given the age and likely daycare exposure, high-dose therapy is strongly preferred 1, 3

Penicillin-Allergic Alternatives

If this child has documented penicillin allergy:

• Cefdinir: 14 mg/kg/day in 1-2 divided doses = 190 mg/day (95 mg twice daily or 190 mg once daily) 1, 2, 4
• Cefpodoxime proxetil: 10 mg/kg/day in 2 divided doses = 136 mg/day (68 mg twice daily) 1, 4
• Cefuroxime axetil: appropriate dosing per weight 1, 4

When to Use Ceftriaxone Instead

Ceftriaxone 50 mg/kg IM/IV as a single dose (680 mg for this 13.6 kg child) is indicated when: 1, 2

• Child is vomiting and cannot tolerate oral medications 1, 2
• Compliance with oral therapy is unlikely 2
• Child has failed initial oral antibiotic therapy after 72 hours 2

Critical Reassessment Timepoint

• Reassess at 72 hours (3 days) 1, 2, 3
• If no improvement or worsening symptoms, switch to high-dose amoxicillin-clavulanate (if not already prescribed) or consider ceftriaxone 1, 2
• If symptoms worsen at any time, immediately evaluate for complications (orbital cellulitis, meningitis) 2

What NOT to Use

• Azithromycin: explicitly contraindicated due to 20-25% resistance rates 1, 6
• Trimethoprim-sulfamethoxazole: high resistance rates (50% for S. pneumoniae) 1
• First-generation cephalosporins (cephalexin): inadequate coverage against H. influenzae 1

Adjunctive Therapies to Enhance Outcomes

• Intranasal corticosteroids (if child can tolerate nasal spray) reduce mucosal inflammation 1
• Saline nasal irrigation for symptomatic relief 1
• Analgesics (acetaminophen or ibuprofen) for pain and fever 1
• Adequate hydration 1

Common Pitfall to Avoid

Do not use standard-dose amoxicillin (45 mg/kg/day) for this high-risk 3-year-old—the age alone mandates consideration of high-dose therapy, and likely daycare attendance makes resistant organisms highly probable. 1, 3, 4