What are the treatment options for bacterial sinusitis?

Treatment of Bacterial Sinusitis

Amoxicillin-clavulanate is the first-line antibiotic for bacterial sinusitis in both adults and children, with amoxicillin alone reserved only for uncomplicated cases in adults without risk factors for resistance. 1, 2, 3

Diagnostic Criteria Before Treatment

Before initiating antibiotics, confirm the diagnosis using one of three clinical presentations 2:

• Persistent illness: Nasal discharge or daytime cough lasting ≥10 days without improvement 2
• Severe onset: Temperature ≥39°C with purulent nasal discharge for ≥3 consecutive days 1, 2
• Worsening course: Initial improvement followed by worsening of respiratory symptoms after 5-7 days 2

First-Line Antibiotic Selection

For Children (Ages 1-18 Years)

Standard-dose amoxicillin (45 mg/kg/day divided twice daily) is appropriate for children who 1, 2:

• Have no antibiotic exposure in the past 4-6 weeks
• Are not attending daycare
• Are aged >2 years

High-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component divided twice daily) is recommended for children with risk factors 1, 2:

• Age <2 years
• Daycare attendance
• Recent antibiotic use (within 4-6 weeks)
• High local prevalence of resistant S. pneumoniae

For Adults

Amoxicillin-clavulanate is the preferred first-line agent over amoxicillin alone due to increasing prevalence of β-lactamase-producing H. influenzae and M. catarrhalis 1, 3. The standard adult dose is 875 mg/125 mg twice daily 3.

High-dose amoxicillin-clavulanate (1750-4000 mg amoxicillin/250 mg clavulanate per day) may be considered in areas with high prevalence of penicillin-resistant S. pneumoniae, though recent evidence suggests standard dosing is equally effective 1, 3, 4, 5.

Alternative Antibiotics for Penicillin Allergy

For non-severe (non-type 1) penicillin allergies 3, 6:

• Cefuroxime, cefpodoxime, or cefdinir (second/third-generation cephalosporins)
• The risk of cross-reactivity with these agents is minimal 3

For severe penicillin allergies in adults 1, 6:

• Respiratory fluoroquinolones (levofloxacin 500-750 mg daily, moxifloxacin, gatifloxacin) with predicted clinical efficacy of 90-92% 1, 7

Avoid azithromycin and other macrolides as they have poor efficacy (77-81% predicted clinical success) due to high resistance rates among S. pneumoniae and H. influenzae 1, 6.

Doxycycline is a suboptimal alternative with only 77-81% predicted clinical efficacy and should be reserved for adults with β-lactam allergies who cannot tolerate fluoroquinolones 1, 6.

Treatment Duration

• Standard duration: 10-14 days for most antibiotics 1, 2, 3
• Alternative approach: Continue for 7 days after symptom resolution, with minimum total duration of 10 days 3
• Fluoroquinolones: Levofloxacin 750 mg can be given for 5 days, or 500 mg for 10-14 days 7

Reassessment at 72 Hours

Mandatory reassessment at 72 hours is evidence-based: only 9% of placebo-treated children who failed at day 3 improved between days 3-10 without intervention 2.

If the patient shows worsening or failure to improve at 72 hours 1, 2, 3:

For Children Initially on Amoxicillin

• Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day) 1, 2
• Alternative: Ceftriaxone 50 mg/kg IM/IV once daily, then switch to oral after improvement 2

For Patients Initially on Amoxicillin-Clavulanate

• Consider third-line options: clindamycin plus cefixime (for penicillin-resistant S. pneumoniae) 2
• In communities with high clindamycin resistance: linezolid plus cefixime 2

Do not simply reassure or continue the same antibiotic—treatment failure at 72 hours predicts continued failure without intervention 2.

When to Initiate Antibiotics vs Observation

For severe or worsening acute bacterial sinusitis: Always initiate antibiotics immediately 1.

For persistent illness (mild symptoms): Either antibiotic therapy or additional 3 days of observation is acceptable, representing an opportunity for shared decision-making 1. The number needed to treat is 3-5, but some children improve spontaneously 1.

Always treat with antibiotics (no observation option) when 1:

• Orbital or intracranial complications are present
• Coexisting acute otitis media, pneumonia, adenitis, or streptococcal pharyngitis

Red Flags Requiring Immediate Specialist Consultation

Initiate IV vancomycin plus ceftriaxone or cefotaxime immediately and obtain urgent imaging for 2:

• Periorbital or orbital swelling
• Impaired extraocular muscle function
• Impaired visual acuity
• Severe headache
• Altered mental status
• Seizures
• Focal neurologic findings

Adjunctive Therapies

• Intranasal corticosteroids: Provide additional benefit when used alongside antibiotics but should not replace antimicrobial therapy 2, 3
• Saline nasal irrigation: Improves mucociliary clearance and reduces congestion 3
• Short-term oral decongestants: May decrease nasal resistance, but avoid prolonged use due to rebound congestion 3

Critical Pitfalls to Avoid

• Do not use azithromycin for empiric treatment due to high resistance rates (predicted efficacy only 77-81%) 1, 6
• Do not obtain imaging (CT/MRI) for uncomplicated treatment failure at 72 hours—imaging does not contribute to diagnosis in straightforward cases 2
• Do not refer to ENT for uncomplicated treatment failure at 72 hours—referral is indicated only after second-line antibiotic failure or when complications are suspected 2
• Avoid antihistamines unless the underlying risk factor is allergic rhinitis 6
• Do not use antibiotics for viral upper respiratory infections that don't meet bacterial sinusitis criteria 3