What is the recommended treatment for bacterial sinusitis?

Treatment of Bacterial Sinusitis

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-7 days is the recommended first-line treatment for acute bacterial sinusitis in adults. 1

Diagnostic Criteria Before Treatment

Before initiating antibiotics, confirm the diagnosis meets one of these criteria:

• Persistent symptoms lasting >10 days without improvement 2
• Severe symptoms with high fever (≥39°C) and purulent nasal discharge for 3-4 consecutive days 1
• Worsening symptoms after initial improvement (double-worsening) 1

The duration criterion is critical—bacterial sinusitis is uncommon in patients symptomatic for less than 10 days, as most cases are viral and self-limited. 2

First-Line Antibiotic Selection

Standard Adult Dosing

• Amoxicillin-clavulanate 875 mg/125 mg twice daily is strongly preferred over plain amoxicillin due to increasing prevalence of β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis 1
• Treatment duration: 5-7 days for uncomplicated cases in adults 1
• High-dose formulation (2 g amoxicillin/125 mg clavulanate twice daily) may be considered for severe infections, though recent evidence shows no clear superiority over standard dosing 1, 3, 4

Pediatric Dosing

• Standard dose: 45 mg/kg/day of amoxicillin component in 2 divided doses for children ≥2 years without recent antibiotic exposure 1
• High dose: 80-90 mg/kg/day of amoxicillin component (maximum 2 g per dose) with 6.4 mg/kg/day clavulanate for children <2 years, those in daycare, or with recent antibiotic use 1
• Treatment duration: 10-14 days in children 1

Penicillin-Allergic Patients

For non-severe penicillin allergy, the risk of cross-reactivity with cephalosporins causing serious allergic reactions is negligible. 1

Recommended alternatives:

• Cefuroxime 1, 5
• Cefpodoxime 1, 5
• Cefdinir 1, 5
• Cefprozil 1

Critical pitfall: Do NOT use azithromycin or other macrolides as first-line therapy due to 20-25% resistance rates among Streptococcus pneumoniae and Haemophilus influenzae. 5, 6

Second-Line Treatment for Failure

If no improvement occurs after 3-5 days of initial therapy or symptoms worsen within 48-72 hours, switch to alternative antibiotics. 1, 5

Second-line options:

• Respiratory fluoroquinolones (levofloxacin 500 mg daily for 10-14 days or 750 mg daily for 5 days, or moxifloxacin) 5, 7
• These agents demonstrate 90-92% predicted clinical efficacy and 100% microbiologic eradication for S. pneumoniae, including multi-drug resistant strains 7
• Reserve fluoroquinolones for treatment failures, complicated sinusitis (frontal, ethmoidal, or sphenoidal involvement), or when major complications are likely 5, 7

Adjunctive Therapies

Intranasal Corticosteroids

• Strongly recommended as adjunctive treatment, particularly in patients with allergic rhinitis, to reduce inflammation and improve outcomes 1, 5

Nasal Saline Irrigation

• Recommended in adults (physiologic or hypertonic saline) to improve mucociliary clearance and reduce nasal congestion 1

Oral Corticosteroids

• May be reasonable for short-term use (e.g., dexamethasone 4 mg) in acute hyperalgic sinusitis (severe pain) or marked mucosal edema when patients fail initial treatment 5
• Should NOT be used as monotherapy—always combine with appropriate antibiotics 5

Monitoring and Reassessment

• Reassess at 72 hours if symptoms worsen or fail to improve 1
• Do not continue ineffective antibiotics beyond 3-5 days—failure to switch therapy leads to prolonged illness and potential complications 1, 5

Special Clinical Situations

Severely Ill or Toxic-Appearing Patients

• Initiate inpatient IV therapy with cefotaxime or ceftriaxone 1
• Obtain otolaryngology consultation for possible sinus aspiration 1

Unable to Tolerate Oral Medications

• Administer ceftriaxone 50 mg/kg IV or IM as a single dose, then transition to oral therapy once tolerated 1

Recurrent Sinusitis

• Immediate antibiotic therapy may be warranted in patients with history of recurrent bacterial sinusitis 2

When to Refer to Specialist

Refer to otolaryngologist, infectious disease specialist, or allergist for:

• Immunocompromised patients 1
• Clinical deterioration despite extended antibiotic courses 1
• Recurrent sinusitis (≥3 episodes per year) with clearing between episodes 1, 5
• Suspected complications (orbital or intracranial involvement) 1

Critical Pitfalls to Avoid

• Do NOT use plain amoxicillin as first-line therapy given high prevalence of β-lactamase-producing organisms 1
• Do NOT routinely cover for MRSA during initial empiric therapy—current data do not support this practice 1
• Do NOT prescribe antibiotics for viral rhinosinusitis—ensure patients meet diagnostic criteria (symptoms >10 days, severe symptoms with high fever for 3-4 days, or worsening after initial improvement) 1
• Do NOT use azithromycin as first-line therapy due to significant resistance 5
• Do NOT use fluoroquinolones as routine first-line therapy—reserve for treatment failures or complicated cases to prevent resistance development 5, 7