What is the recommended treatment for acute bacterial sinusitis?

Acute Bacterial Sinusitis Treatment

First-Line Antibiotic Selection

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line antibiotic for adults with acute bacterial sinusitis. 1

The rationale for this recommendation centers on increasing prevalence of β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis, which plain amoxicillin cannot adequately cover. 1 The combination formulation provides superior coverage against these resistant organisms while maintaining excellent activity against Streptococcus pneumoniae, the most common pathogen. 1

For uncomplicated cases without recent antibiotic exposure (within 4-6 weeks), plain amoxicillin 500 mg twice daily for mild disease or 875 mg twice daily for moderate disease remains an acceptable alternative. 1, 2 However, given current resistance patterns, amoxicillin-clavulanate is generally preferred. 1

Treatment Duration

• Standard duration is 5-10 days, with most guidelines recommending treatment until symptom-free for 7 days (typically 10-14 days total). 1, 2
• Shorter 5-7 day courses demonstrate comparable efficacy with fewer side effects. 1
• The key is ensuring adequate duration to prevent relapse—minimum 5 days, but extending to 10-14 days if symptoms persist. 1, 2

Penicillin-Allergic Patients

For documented penicillin allergy, second- or third-generation cephalosporins are the preferred alternatives, as the risk of cross-reactivity is negligible. 1

Recent evidence demonstrates that serious allergic reactions to second- and third-generation cephalosporins in penicillin-allergic patients are almost nil. 1 Recommended options include:

• Second-generation: Cefuroxime-axetil 3, 1, 2
• Third-generation: Cefpodoxime-proxetil, cefdinir, or cefprozil 1, 2

These cephalosporins provide excellent coverage against the typical sinusitis pathogens, with third-generation agents offering superior activity against H. influenzae. 1, 2

When to Use Fluoroquinolones

Reserve fluoroquinolones (levofloxacin 500-750 mg once daily or moxifloxacin 400 mg once daily) for specific situations only—do not use as routine first-line therapy. 1, 2

Appropriate indications include:

• Treatment failures after first-line antibiotics 1, 2
• Complicated sinusitis (frontal, ethmoidal, or sphenoidal involvement) 3, 1, 2
• Multi-drug resistant S. pneumoniae 1, 4
• Severe beta-lactam allergy (true anaphylaxis) 1, 2

Fluoroquinolones demonstrate 90-92% predicted clinical efficacy and provide excellent coverage against resistant organisms, but should be reserved to prevent resistance development. 1, 4

Pediatric Dosing

• Standard therapy: Amoxicillin 45 mg/kg/day in 2 divided doses for children without recent antibiotic use 1, 2
• High-dose therapy: Amoxicillin-clavulanate 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses for children with risk factors (age <2 years, daycare attendance, recent antibiotic use, or areas with high prevalence of resistant S. pneumoniae) 1, 2
• Duration: 10-14 days for children 1

Diagnostic Confirmation Before Treatment

Antibiotics should only be initiated when acute bacterial sinusitis is confirmed by one of three clinical patterns: 1

1. Persistent symptoms: ≥10 days without clinical improvement 1
2. Severe onset: High fever (>39°C) and purulent nasal discharge for ≥3 consecutive days 1, 5
3. "Double sickening": Worsening symptoms after initial improvement from a viral URI 1, 5

Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7 days without antibiotics. 1 Prescribing antibiotics for viral rhinosinusitis contributes to unnecessary adverse effects and antimicrobial resistance. 1

Treatment Failure Protocol

If no improvement occurs after 3-5 days of initial therapy, switch to a different antibiotic. 1, 2

The treatment failure algorithm:

1. First-line failure (amoxicillin or amoxicillin-clavulanate): Switch to high-dose amoxicillin-clavulanate (4 g amoxicillin/250 mg clavulanate per day) or a respiratory fluoroquinolone 1, 2
2. Second-line failure: Consider respiratory fluoroquinolone (levofloxacin 500-750 mg once daily or moxifloxacin 400 mg once daily) 1, 2
3. Persistent failure: Reassess diagnosis, consider complications, imaging, or referral to otolaryngology 1, 2

Adjunctive Therapies

Intranasal corticosteroids are recommended as adjuncts to antibiotic therapy in acute sinusitis. 1, 2

Additional supportive measures include:

• Analgesics (acetaminophen, NSAIDs) for pain relief 1, 2
• Saline nasal irrigation for symptomatic relief 1
• Adequate hydration 1
• Short-term oral corticosteroids for patients with marked mucosal edema or who fail to respond to initial treatment 1, 2

Critical Pitfalls to Avoid

• Never use azithromycin or other macrolides as first-line therapy due to 20-25% resistance rates in S. pneumoniae and H. influenzae. 1, 2
• Ensure adequate treatment duration (minimum 5 days, typically 7-10 days) to prevent relapse. 1, 2
• Reassess at 3 days (pediatrics) or 7 days (adults) if no improvement to avoid treatment failure. 1, 2
• Do not prescribe antibiotics for viral rhinosinusitis—wait at least 10 days unless severe symptoms are present. 1
• Do not use mucus color alone to determine antibiotic need, as color reflects neutrophils, not bacteria. 1
• Avoid fluoroquinolone overuse to prevent resistance development—reserve for treatment failures or severe disease. 1, 2

Special Anatomic Considerations

For frontal, ethmoidal, or sphenoidal sinusitis, antibiotic therapy is definitely indicated due to high risk of complications. 3, 2

These sites require more aggressive treatment:

• Consider fluoroquinolones (levofloxacin or moxifloxacin) as first-line therapy due to potential for serious complications 3, 2
• Clinical signs suggestive of complicated sinusitis (meningeal syndrome, exophthalmos, palpebral edema, ocular mobility disorders, severe pain preventing sleep) require hospitalization, bacteriological testing, and parenteral antibiotic therapy 3