What is the recommended treatment for a patient with acute bacterial rhinosinusitis?

Treatment of Acute Bacterial Rhinosinusitis

For adults with acute bacterial rhinosinusitis, amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-7 days is the preferred first-line antibiotic, providing 90-92% predicted clinical efficacy against the major pathogens including β-lactamase-producing organisms. 1, 2

Confirm the Diagnosis Before Prescribing Antibiotics

Before initiating antibiotic therapy, verify the patient meets one of three diagnostic criteria that distinguish bacterial from viral rhinosinusitis 3, 2:

• Persistent symptoms ≥10 days without clinical improvement (nasal discharge, congestion, facial pain/pressure) 3, 2
• Severe symptoms for ≥3-4 consecutive days at illness onset: high fever (≥39°C/102°F) with purulent nasal discharge or facial pain 3, 2
• "Double-sickening": worsening symptoms after initial improvement from a viral URI that lasted 5-6 days 3, 2

Critical pitfall: 98-99.5% of acute rhinosinusitis is viral and resolves spontaneously within 7-10 days without antibiotics—do not prescribe antibiotics for symptoms <10 days unless severe features are present. 2, 4

First-Line Antibiotic Selection

Standard Patients (No Risk Factors)

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-7 days is the preferred first-line agent due to increasing prevalence of β-lactamase-producing Haemophilus influenzae (50% of strains) and Moraxella catarrhalis (90-100% of strains). 1, 2, 5

• Predicted clinical efficacy: 90-92% 1
• Covers Streptococcus pneumoniae, β-lactamase-producing H. influenzae, and M. catarrhalis 1, 2
• Treatment duration: 5-7 days for adults (shorter courses have comparable efficacy with fewer adverse effects) 1, 2

High-Risk Patients Requiring High-Dose Therapy

High-dose amoxicillin-clavulanate (2 g amoxicillin/125 mg clavulanate twice daily) should be used for patients with 1, 2:

• Recent antibiotic use within past 4-6 weeks 2
• Age >65 years 1
• Moderate-to-severe symptoms 1, 2
• Comorbid conditions (diabetes, COPD, immunosuppression) 1, 2
• Daycare attendance (pediatrics) 1

Watchful Waiting as an Alternative

For adults with uncomplicated acute bacterial sinusitis, watchful waiting without immediate antibiotics is an appropriate initial strategy when reliable follow-up can be assured. 1, 2

• Start antibiotics only if no improvement by 7 days or symptoms worsen at any time 1, 2
• Provide symptomatic treatment during observation period 2, 4
• This approach reduces unnecessary antibiotic exposure while maintaining equivalent outcomes 2

Treatment for Penicillin-Allergic Patients

Non-Severe (Type II) Penicillin Allergy

For patients with non-anaphylactic penicillin reactions (rash, delayed reactions), second- or third-generation cephalosporins are safe and effective 1, 2:

• Cefuroxime-axetil (second-generation) 1, 6
• Cefpodoxime-proxetil or cefdinir (third-generation, superior H. influenzae coverage) 1, 6
• Cross-reactivity risk with cephalosporins is negligible in non-Type I allergies 1

Severe (Type I) Penicillin Allergy

For documented anaphylaxis or Type I hypersensitivity, respiratory fluoroquinolones are the treatment of choice 1, 2:

• Levofloxacin 500 mg once daily for 10-14 days 1, 7
• Moxifloxacin 400 mg once daily for 10 days 1
• Predicted clinical efficacy: 90-92% 1
• Excellent coverage against drug-resistant S. pneumoniae and β-lactamase-producing organisms 1

Alternative for mild disease: Doxycycline 100 mg once daily for 10 days (predicted efficacy 77-81%, suboptimal due to limited H. influenzae activity) 1, 4

What NOT to Use

Azithromycin and other macrolides should NOT be used due to resistance rates of 20-25% for both S. pneumoniae and H. influenzae. 1, 6, 8

Trimethoprim-sulfamethoxazole should NOT be used due to 50% resistance in S. pneumoniae and 27% resistance in H. influenzae. 1, 4

First-generation cephalosporins (cephalexin) should NOT be used due to inadequate coverage against H. influenzae (50% β-lactamase producing). 1

Treatment Monitoring and Reassessment

Critical Timepoints

Reassess at 3-5 days 1, 2:

• If no improvement or worsening: switch to second-line therapy immediately 1, 2
• Switch to high-dose amoxicillin-clavulanate or respiratory fluoroquinolone 1

Reassess at 7 days 1, 2:

• If symptoms persist: reconfirm diagnosis, exclude complications, consider imaging 1, 2
• Switch to broader-spectrum antibiotics if bacterial sinusitis confirmed 1

Common pitfall: Waiting beyond 7 days to change therapy in non-responders delays effective treatment and may allow complications to develop. 1

Essential Adjunctive Therapies

These should be offered to all patients regardless of antibiotic choice to improve symptom resolution 1, 2:

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily): reduce mucosal inflammation with strong evidence from multiple RCTs 1, 2
• Saline nasal irrigation (high-volume, hypertonic or normal saline): provides symptomatic relief and removes mucus 1, 2, 4
• Analgesics (acetaminophen or ibuprofen): for pain and fever 1, 2
• Adequate hydration 1

Decongestants may provide symptomatic relief but have limited evidence; topical decongestants should not be used >3 days to avoid rebound congestion. 4

Antihistamines are NOT recommended unless underlying allergic rhinitis is present. 2

When to Refer to a Specialist

Refer to otolaryngology or infectious disease if 1, 2:

• No improvement after 7 days of appropriate second-line antibiotic therapy 1
• Worsening symptoms at any time (suspect complications) 1, 2
• Recurrent sinusitis (≥3 episodes per year) 1
• Suspected complications: orbital cellulitis, meningitis, brain abscess 1
• Immunocompromised patients with persistent symptoms 2

Pediatric Considerations

For children with acute bacterial sinusitis 1, 2:

• Standard-dose amoxicillin: 45 mg/kg/day divided twice daily for 10-14 days 1
• High-dose amoxicillin: 80-90 mg/kg/day divided twice daily for high-risk children (age <2 years, daycare, recent antibiotics) 1, 2
• High-dose amoxicillin-clavulanate: 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate divided twice daily for treatment failures 1
• Reassess at 72 hours: switch to high-dose amoxicillin-clavulanate if no improvement 1

Treatment Duration Summary

• Adults: 5-7 days for uncomplicated cases (shorter courses have comparable efficacy with fewer adverse effects) 1, 2
• Children: 10-14 days minimum 1, 2
• Alternative guideline: treat until symptom-free for 7 days (typically 10-14 days total) 1, 6

Expected Timeline for Improvement

• By 3-5 days: Most patients should show noticeable improvement (reduction in fever, facial pain, purulent discharge) 1
• By 7 days: 73-85% of patients show clinical improvement even with placebo 1
• By 10-14 days: 86-91% achieve cure or improvement with appropriate antibiotics 1

Important context: Even bacterial sinusitis shows 73% spontaneous improvement by 7-12 days without antibiotics, which is why watchful waiting is a reasonable strategy for uncomplicated cases. 1