What is the recommended antibiotic treatment for bacterial sinusitis in a 12-year-old?

Antibiotic Treatment for Sinusitis in a 12-Year-Old

For a 12-year-old with acute bacterial sinusitis, amoxicillin at 45 mg/kg/day divided twice daily OR high-dose amoxicillin-clavulanate at 90 mg/kg/day (of the amoxicillin component) divided twice daily for 10-14 days is the recommended first-line treatment. 1

Determining When Antibiotics Are Needed

Before prescribing antibiotics, confirm the diagnosis using one of three clinical presentations 1:

• Persistent illness: Nasal discharge (any quality) or daytime cough lasting ≥10 days without improvement 1
• Severe onset: High fever (≥39°C/102.2°F) with purulent nasal discharge for ≥3 consecutive days 1
• Worsening course: Initial improvement followed by worsening of respiratory symptoms after 5-7 days 1

For persistent illness only, you may offer additional outpatient observation for 3 days instead of immediate antibiotics, using shared decision-making with the family 1. However, severe or worsening presentations always require immediate antibiotic therapy 1, 2.

First-Line Antibiotic Selection

Standard-Dose Amoxicillin (45 mg/kg/day)

Use this when the child has 1, 3:

• No antibiotic exposure in the past 4-6 weeks
• Not attending daycare
• Age >2 years
• Low community prevalence of resistant S. pneumoniae

High-Dose Amoxicillin-Clavulanate (90 mg/kg/day of amoxicillin component)

Use this when ANY of the following risk factors are present 1, 2, 3:

• Age <2 years
• Daycare attendance
• Recent antibiotic use (within 4-6 weeks)
• High local prevalence of resistant S. pneumoniae (>10-15%)
• Failed initial amoxicillin therapy

The rationale is that 10-42% of H. influenzae and nearly 100% of M. catarrhalis produce β-lactamase, making them resistant to amoxicillin alone 3.

Penicillin Allergy Alternatives

For non-severe penicillin allergy, second- or third-generation cephalosporins carry minimal cross-reactivity risk 2, 4:

• Cefdinir 1, 3
• Cefuroxime 1, 3
• Cefpodoxime 1, 3

Critical caveat: Avoid azithromycin and trimethoprim-sulfamethoxazole due to high resistance rates among S. pneumoniae 3. Despite FDA approval of azithromycin for sinusitis 5, resistance patterns make it inappropriate for first-line use.

Treatment Duration

Treat for 10-14 days total 1, 2. An alternative approach is to continue antibiotics for 7 days after the patient becomes symptom-free, which ensures a minimum of 10 days and individualizes therapy 1. While some research suggests 5-day courses may be adequate for uncomplicated cases 6, 7, the American Academy of Pediatrics guideline supports the longer duration for children 1.

When to Escalate Therapy

Reassess at 72 hours 1, 2. If the child shows worsening symptoms OR failure to improve within 72 hours, change management 1:

Second-Line Options:

• High-dose amoxicillin-clavulanate (if not already used) at 90 mg/kg/day 1, 8
• Ceftriaxone 50 mg/kg IM/IV as a single dose (maximum 2 grams) if the child cannot tolerate oral medications or adherence is questionable 2

If ceftriaxone is used and clinical improvement occurs within 24 hours, switch to oral high-dose amoxicillin-clavulanate to complete the 10-14 day course 2.

Red Flags Requiring Immediate Imaging and Specialist Consultation

Obtain contrast-enhanced CT and consult otolaryngology, ophthalmology, and infectious disease immediately if 1, 2:

• Periorbital or orbital swelling with proptosis
• Impaired extraocular muscle function or painful eye movements
• Impaired visual acuity
• Severe headache with photophobia
• Altered mental status
• Seizures or focal neurologic findings
• Pott's puffy tumor (frontal bone swelling suggesting osteomyelitis)

For suspected orbital or intracranial complications, initiate IV vancomycin (to cover methicillin-resistant S. pneumoniae) plus ceftriaxone or cefotaxime immediately 1.

Common Pitfalls to Avoid

• Do NOT obtain imaging for uncomplicated sinusitis 2, 3—diagnosis is clinical
• Do NOT use azithromycin or trimethoprim-sulfamethoxazole despite their convenience, due to resistance 3
• Do NOT prescribe antibiotics for symptoms lasting <10 days unless severe onset or worsening course is present 1
• Do NOT continue the same antibiotic beyond 72 hours without improvement—this delays appropriate therapy 1

Adjunctive Therapy

Intranasal corticosteroids may provide additional benefit when used alongside antibiotics 1, though they should not replace antimicrobial therapy.