What is the first-line antibiotic treatment for acute bacterial sinusitis in pediatric patients?

First-Line Antibiotic Treatment for Acute Bacterial Sinusitis in Pediatric Patients

Amoxicillin with or without clavulanate is the first-line antibiotic treatment for acute bacterial sinusitis in children, with dosing determined by the child's risk factors for antibiotic-resistant organisms. 1

Diagnostic Criteria Before Starting Antibiotics

The diagnosis of acute bacterial sinusitis requires one of three clinical presentations 1:

• Persistent illness: Nasal discharge (any quality) or daytime cough lasting >10 days without improvement 1
• Severe onset: Concurrent fever ≥39°C (102.2°F) and purulent nasal discharge for at least 3 consecutive days 1
• Worsening course: Initial improvement followed by worsening or new onset of nasal discharge, daytime cough, or fever 1

Do not obtain imaging studies (CT or MRI) to distinguish bacterial sinusitis from viral URI, as they do not contribute to diagnosis in uncomplicated cases. 1

First-Line Antibiotic Selection Algorithm

Standard-Dose Amoxicillin (45 mg/kg/day divided twice daily)

Use for children who meet ALL of the following criteria 2, 3:

• Age >2 years
• No daycare attendance
• No antibiotic exposure in the past 4-6 weeks
• Low local prevalence of resistant S. pneumoniae

High-Dose Amoxicillin-Clavulanate (90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate, divided twice daily)

Use for children with ANY of the following risk factors 2, 3:

• Age <2 years
• Daycare attendance
• Antibiotic use within the past 4-6 weeks
• High local prevalence of resistant S. pneumoniae (>10% nonsusceptible)
• Severe presentation at onset

Treatment Duration

Treat for 10-14 days total, continuing until the child is symptom-free for 7 days. 1, 3

Penicillin-Allergic Patients

For documented penicillin allergy, use one of the following 2, 3:

• Cefdinir (14 mg/kg/day divided once or twice daily)
• Cefuroxime axetil (30 mg/kg/day divided twice daily)
• Cefpodoxime proxetil (10 mg/kg/day divided twice daily)

Second- and third-generation cephalosporins carry minimal cross-reactivity risk, even in patients with documented penicillin allergy. 2

Do NOT use azithromycin or other macrolides as first-line therapy due to 20-25% resistance rates among S. pneumoniae and H. influenzae. 4, 5

When to Treat Immediately vs. Observe

Immediate Antibiotic Treatment Required 1:

• Severe onset presentation (high fever + purulent discharge ≥3 days)
• Worsening course presentation

Option to Observe for 3 Days Before Treating 1:

• Persistent illness presentation only (symptoms >10 days without improvement)
• Shared decision-making with parents based on symptom severity
• Must ensure reliable follow-up

Reassessment at 72 Hours

Mandatory reassessment is required if the child shows worsening symptoms or failure to improve within 72 hours. 1, 3

If treatment failure at 72 hours 2, 3:

• Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day) if initially treated with standard-dose amoxicillin
• Consider ceftriaxone 50 mg/kg IM/IV once daily if the child cannot tolerate oral medication or is vomiting 2
• After clinical improvement with ceftriaxone, switch to oral high-dose amoxicillin-clavulanate to complete 10-14 days total 2

Alternative for Non-Oral Administration

Ceftriaxone 50 mg/kg (maximum 2 grams) as a single IM or IV dose is indicated when 2:

• The child is unlikely to be adherent to initial oral antibiotic doses
• The child is vomiting or cannot tolerate oral medication
• The child has failed initial oral antibiotic therapy after 72 hours

After 24 hours, if clinical improvement occurs, switch to oral high-dose amoxicillin-clavulanate to complete the treatment course. 2

Red Flags Requiring Immediate Imaging and Specialist Consultation

Obtain contrast-enhanced CT scan and initiate IV antibiotics immediately if any of the following are present 2, 3:

• Periorbital or orbital swelling with proptosis
• Impaired extraocular muscle function
• Impaired visual acuity
• Severe headache with photophobia
• Altered mental status or seizures
• Focal neurologic findings

For suspected orbital or intracranial complications, initiate IV vancomycin plus ceftriaxone or cefotaxime immediately. 3

Common Pitfalls to Avoid

Do not use trimethoprim/sulfamethoxazole or azithromycin due to high resistance rates (20-42% for TMP/SMX, 20-25% for macrolides). 2, 4

Do not obtain imaging for uncomplicated cases—diagnosis is clinical, and imaging does not contribute to management decisions in straightforward presentations. 1, 3

Do not stop antibiotics early—complete the full 10-14 day course even after symptoms improve to prevent relapse (12-13% relapse rate documented in studies). 6

Ensure adequate dosing—underdosing amoxicillin (using 40 mg/kg/day instead of 45-90 mg/kg/day) contributes to treatment failure, particularly with resistant S. pneumoniae. 7

Adjunctive Therapy

Intranasal corticosteroids may provide additional benefit when used alongside antibiotics, but should not replace antimicrobial therapy. 3