What are the treatment guidelines for acute sinusitis?

Acute Sinusitis Diagnostic Criteria and Treatment Guidelines

Diagnostic Criteria for Acute Bacterial Sinusitis

Acute sinusitis is defined as symptoms and signs lasting less than 4 weeks. 1, 2

The diagnosis is primarily clinical, based on three distinct presentations 1, 3:

• Persistent symptoms: Nasal discharge, congestion, or cough lasting more than 10 days but less than 30 days without improvement 1, 3
• Severe onset: High fever (≥39°C/102.2°F) with purulent nasal discharge for at least 3-4 consecutive days 1, 3
• Worsening symptoms: Initial improvement from a viral upper respiratory infection followed by worsening of respiratory symptoms after 5-6 days (double-worsening pattern) 1, 3

Physical examination findings include purulent nasal discharge, sinus tenderness on palpation, and nasal congestion 1, 4. Radiographic imaging (CT or plain films) may be used to enhance diagnostic certainty, particularly in adults and older children (>6 years), though imaging is not required for clinical diagnosis 1, 3.

First-Line Antibiotic Treatment

Amoxicillin remains the first-line antibiotic choice for uncomplicated acute bacterial sinusitis in both adults and children. 1, 2

Adult Dosing

• Standard dose: Amoxicillin 500 mg twice daily for mild disease without recent antibiotic exposure 1, 2
• High dose: Amoxicillin 875 mg twice daily for moderate disease or areas with high prevalence of resistant Streptococcus pneumoniae 1, 2
• Treatment duration: 10-14 days, or continue until symptom-free for 7 days 1, 2

Pediatric Dosing

• Standard dose: Amoxicillin 45 mg/kg/day divided into 2 doses for mild disease 1, 2
• High dose: Amoxicillin 80-90 mg/kg/day divided into 2 doses for children under 2 years, those in daycare, or with recent antibiotic use 1, 2

Amoxicillin-clavulanate is an acceptable alternative first-line option, particularly for patients with recent antibiotic exposure or more severe disease 2. The dose is 875 mg/125 mg twice daily for adults or 80-90 mg/kg/day of the amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses for children 1, 2. Recent high-quality evidence shows no significant benefit of high-dose over standard-dose amoxicillin-clavulanate, though diarrhea rates are similar 5.

Treatment for Penicillin-Allergic Patients

For patients with non-anaphylactic penicillin allergy (such as rash without airway compromise), second- or third-generation cephalosporins are safe and appropriate 1, 2:

• Cefuroxime-axetil 1, 2
• Cefpodoxime-proxetil 1, 2
• Cefdinir (preferred due to high patient acceptance) 2, 6

Recent evidence demonstrates that the risk of serious allergic reactions to second- and third-generation cephalosporins in penicillin-allergic patients is negligible 1, 2.

For patients with true anaphylactic reactions to penicillin, respiratory fluoroquinolones are the treatment of choice 2, 6:

• Levofloxacin 500-750 mg once daily 2, 7
• Moxifloxacin 400 mg once daily 2

Critical pitfall: Azithromycin and other macrolides should NOT be used as first-line therapy due to 20-25% resistance rates among S. pneumoniae and H. influenzae 2. Trimethoprim-sulfamethoxazole also has unacceptably high resistance rates 2.

Second-Line Treatment for Treatment Failure

Reassess patients who show no improvement within 72 hours (pediatrics) or 3-5 days (adults) of initiating therapy. 1, 2

For treatment failure or poor response, switch to 1, 2:

• High-dose amoxicillin-clavulanate (90 mg/kg amoxicillin with 6.4 mg/kg clavulanate, not exceeding 2 g every 12 hours) 1
• Respiratory fluoroquinolones (levofloxacin 500-750 mg daily or moxifloxacin 400 mg daily) 2, 7
• Second-generation cephalosporins (cefuroxime) or third-generation cephalosporins (cefpodoxime, cefdinir) 1, 2

For sinusitis failing to improve after 21-28 days, consider broader-spectrum coverage with or without anaerobic coverage using clindamycin or metronidazole 1.

Treatment Based on Anatomic Location

For maxillary sinusitis (the most common type), standard first-line antibiotics are appropriate 2. Clinical features include unilateral or bilateral infraorbital pain that worsens when bending forward, is pulsatile, and peaks in the evening or night 2.

For frontal, ethmoidal, or sphenoidal sinusitis, fluoroquinolones should be considered due to the potential for serious intracranial complications 2. These locations carry higher risk and warrant more aggressive initial therapy 2.

Adjunctive Therapies

Intranasal corticosteroids are recommended as adjunctive therapy in both acute and chronic sinusitis 1, 2. They help reduce mucosal inflammation and improve sinus drainage 1.

Short-term oral corticosteroids may be reasonable when patients fail initial treatment, demonstrate nasal polyposis, or have marked mucosal edema 1, 2. A typical regimen is dexamethasone 4 mg for acute hyperalgic sinusitis (severe pain) 2.

Supportive measures include adequate rest, hydration, analgesics, warm facial packs, steamy showers, and sleeping with the head of the bed elevated 1, 2.

Special Considerations and Common Pitfalls

Watchful waiting without antibiotics is an appropriate initial strategy for adults with uncomplicated acute bacterial sinusitis when reliable follow-up can be assured, with antibiotics started if no improvement occurs by 7 days or if symptoms worsen at any time 2.

Complete the full antibiotic course even after symptoms improve to prevent relapse 2. Inadequate treatment duration is a common cause of treatment failure 2.

Avoid cefixime and ceftibuten as they have poor activity against penicillin-resistant S. pneumoniae and should not be used as monotherapy 6.

Reserve fluoroquinolones for second-line therapy, complicated sinusitis, or treatment failures to minimize resistance development 2. They should not be routine first-line therapy 2.

For recurrent sinusitis (≥3 episodes per year), evaluate for underlying risk factors including allergic rhinitis, non-allergic rhinitis, structural abnormalities, and immunodeficiency 1, 2. Consider referral to an allergist-immunologist or otolaryngologist 1, 2.

Microbiology

The predominant bacterial pathogens are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis 1, 3. These organisms account for more than 50% of acute sinusitis cases in adults and two-thirds of cases in children 1. Beta-lactamase production is increasingly common, occurring in up to 20% of H. influenzae strains and 50-70% of M. catarrhalis strains 1.