What is the appropriate treatment and dosing for acute bacterial sinusitis in a 1‑year‑old infant without recent β‑lactam exposure or penicillin allergy?

Treatment of Acute Bacterial Sinusitis in a 1-Year-Old

For a 1-year-old with acute bacterial sinusitis and no recent β-lactam exposure or penicillin allergy, prescribe amoxicillin 45 mg/kg/day divided into two doses for 10–14 days. 1, 2

Diagnostic Confirmation

Before initiating antibiotics, confirm the diagnosis using one of three clinical patterns:

• Persistent illness: nasal discharge (any quality) or daytime cough lasting >10 days without improvement 1
• Worsening course: new onset or worsening of nasal discharge, daytime cough, or fever after initial improvement from a viral URI 1
• Severe onset: concurrent fever ≥39°C (102.2°F) and purulent nasal discharge for at least 3 consecutive days 1

Imaging is not indicated for uncomplicated acute bacterial sinusitis in children—the diagnosis is purely clinical. 1

First-Line Antibiotic Therapy

Standard-Dose Amoxicillin (Preferred for Low-Risk Children)

• Dose: 45 mg/kg/day divided into 2 doses 1, 2, 3
• Duration: 10–14 days total, or continue for 7 days after the child becomes symptom-free 1, 2, 3
• This regimen is appropriate because your patient has no recent antibiotic exposure (past 4–6 weeks), is not in daycare, and has no penicillin allergy 2, 3

High-Dose Amoxicillin-Clavulanate (Reserve for High-Risk Children)

• Dose: 80–90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate, divided into 2 doses 1, 2, 3
• Indications: age <2 years, daycare attendance, antibiotic use within past 4–6 weeks, or high local prevalence (>10%) of penicillin-resistant Streptococcus pneumoniae 1, 2, 3
• Your 1-year-old meets the age criterion (<2 years), so high-dose amoxicillin-clavulanate is a reasonable alternative if you anticipate resistant organisms 2, 3

Critical 72-Hour Reassessment

• Reassess at 72 hours: if symptoms are worsening or failing to improve, switch immediately to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component) 1, 2, 3
• Treatment failure at 72 hours suggests β-lactamase-producing organisms (Haemophilus influenzae or Moraxella catarrhalis) that require clavulanate coverage 2, 3
• Do not continue ineffective therapy beyond 72 hours—early escalation prevents complications and unnecessary prolonged exposure 2, 3

Alternative for Vomiting or Non-Compliance

• If the child is vomiting or cannot tolerate oral medications, give ceftriaxone 50 mg/kg IM or IV as a single dose 2, 3
• After clinical improvement, switch to oral amoxicillin to complete the 10–14 day course 2, 3

Alternatives for Penicillin Allergy (Not Applicable Here)

• For non-Type I penicillin allergy, use a second- or third-generation cephalosporin (cefdinir, cefuroxime axetil, or cefpodoxime proxetil) for 10 days 2, 3
• For severe Type I/anaphylactic allergy, consider levofloxacin (though fluoroquinolones are generally avoided in children) 2, 3

Adjunctive Therapies

• Intranasal corticosteroids may provide additional benefit when used alongside antibiotics, but should not replace antimicrobial therapy 2
• Analgesics (acetaminophen or ibuprofen) for pain and fever management 2
• Saline nasal irrigation for symptomatic relief 2, 3

Red Flags Requiring Immediate Escalation

Suspect orbital or intracranial complications if the child develops:

• Periorbital or orbital swelling, impaired extraocular muscle function, impaired visual acuity 2
• Severe headache, altered mental status, seizures, or focal neurologic findings 2
• Management: immediate contrast-enhanced CT imaging, IV antibiotics (vancomycin plus ceftriaxone or cefotaxime), and urgent ENT/neurosurgery consultation 2, 3

Common Pitfalls to Avoid

• Do not use azithromycin—resistance rates of S. pneumoniae and H. influenzae to macrolides exceed 20–25%, making it ineffective 2, 3, 4
• Do not obtain imaging (CT or MRI) for uncomplicated bacterial sinusitis—imaging does not contribute to diagnosis in straightforward cases 1, 2, 3
• Do not use first-generation cephalosporins (e.g., cephalexin)—they lack adequate coverage against β-lactamase-producing H. influenzae 2, 3
• Ensure adequate treatment duration (minimum 10 days for children)—shorter courses increase relapse risk 2, 3