What is the recommended treatment for bacterial sinusitis?

Treatment of Bacterial Sinusitis

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the first-line antibiotic for acute bacterial sinusitis in adults, providing superior coverage against β-lactamase-producing organisms compared to amoxicillin alone. 1, 2

Confirming the Diagnosis Before Prescribing Antibiotics

Before initiating antibiotic therapy, confirm the patient meets one of three diagnostic criteria for acute bacterial sinusitis (not viral rhinosinusitis):

• Persistent symptoms ≥10 days without clinical improvement 1, 2
• Severe symptoms for ≥3-4 consecutive days: fever ≥39°C with purulent nasal discharge and facial pain 1, 2
• "Double sickening": worsening symptoms after initial improvement from a viral upper respiratory infection 1, 2

Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics—do not prescribe antibiotics for symptoms lasting less than 10 days unless severe features are present. 1

First-Line Antibiotic Selection

Amoxicillin-clavulanate is strongly preferred over plain amoxicillin due to increasing prevalence of β-lactamase-producing Haemophilus influenzae (nearly 50% of strains) and Moraxella catarrhalis (90-100% of strains). 1, 2

Standard Dosing for Adults

• Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days 1, 2
• Predicted clinical efficacy: 90-92% against major pathogens 3, 1

High-Dose Regimen (When Indicated)

Use high-dose amoxicillin-clavulanate (2 g amoxicillin/125 mg clavulanate twice daily) for patients with: 1, 2

• Recent antibiotic use within the past 4-6 weeks
• Age >65 years
• Moderate-to-severe symptoms
• Comorbid conditions or immunocompromised state
• High local prevalence of drug-resistant Streptococcus pneumoniae

Important caveat: Recent research shows high-dose amoxicillin-clavulanate does not provide superior clinical outcomes compared to standard dosing but significantly increases severe diarrhea (15.8% vs 4.8%). 4, 5 Reserve high-dose therapy only for the specific risk factors listed above.

Pediatric Dosing

• Standard dose: 45 mg/kg/day of amoxicillin component in 2 divided doses for children ≥2 years without recent antibiotic exposure 1, 2
• 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, 2

Treatment Duration

• Adults: 5-7 days is sufficient for uncomplicated cases 1, 2
• Children: 10-14 days remains the standard recommendation 1, 2
• Continue treatment until symptom-free for 7 days (typically 10-14 days total) 3, 1

Shorter 5-7 day courses have comparable efficacy to traditional 10-day regimens with fewer adverse effects. 1

Penicillin-Allergic Patients

Non-Severe Penicillin Allergy (Rash, Delayed Reactions)

Second- or third-generation cephalosporins are safe and effective alternatives—the risk of cross-reactivity causing serious allergic reactions is negligible. 1, 2

Recommended alternatives: 3, 1, 2

• Cefuroxime-axetil (second-generation cephalosporin)
• Cefpodoxime-proxetil (third-generation, superior activity against H. influenzae)
• Cefdinir (third-generation, excellent coverage)
• Cefprozil (second-generation)

Severe Penicillin Allergy (Anaphylaxis/Type I Hypersensitivity)

Respiratory fluoroquinolones are the first-line choice when β-lactams are contraindicated: 3, 1

• Levofloxacin 500 mg once daily for 10-14 days (predicted efficacy 90-92%) 3, 1
• Moxifloxacin 400 mg once daily for 10 days (predicted efficacy 90-92%) 3, 1

Alternative option: Doxycycline 100 mg once daily for 10 days (predicted efficacy 77-81%, significantly lower than fluoroquinolones). 3, 1

Critical pitfall: Do NOT use azithromycin or other macrolides as first-line therapy—resistance rates exceed 20-25% for both S. pneumoniae and H. influenzae, making them ineffective in the majority of cases. 1, 2, 6

Watchful Waiting as an Alternative Strategy

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 occurs by 7 days or symptoms worsen at any time 1
• Approximately 73% of bacterial sinusitis shows spontaneous improvement by 7-12 days without antibiotics 1
• Number needed to treat with antibiotics is 10-15 to get one additional person better after 7-15 days 1

Reassessment and Treatment Failure Protocol

Critical Reassessment Timepoints

• At 3-5 days: If no improvement or worsening symptoms, switch to second-line therapy immediately 3, 1, 2
• At 7 days: Reconfirm diagnosis and consider complications or alternative diagnoses if symptoms persist 1, 2
• Pediatric patients: Reassess at 72 hours 1, 2

Second-Line Antibiotic Options (After Treatment Failure)

If initial amoxicillin-clavulanate fails after 3-5 days, switch to: 3, 1

1. Respiratory fluoroquinolones (preferred):

   • Levofloxacin 500 mg once daily for 10-14 days 3, 1
   • Moxifloxacin 400 mg once daily for 10 days 3, 1
   • Predicted clinical efficacy: 90-92% against drug-resistant S. pneumoniae and β-lactamase-producing H. influenzae 3, 1

2. Third-generation cephalosporins:

   • Cefpodoxime proxetil (superior activity against H. influenzae) 3, 1
   • Cefdinir 3, 1

3. Ceftriaxone (for patients unable to tolerate oral medications):

   • Adults: 1-2 g IM or IV once daily for 5 days 1
   • Children: 50 mg/kg IM or IV once daily for 5 days 1

Essential Adjunctive Therapies

These adjunctive therapies should be offered to ALL patients regardless of antibiotic choice to improve symptom resolution and outcomes:

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily): Reduce mucosal inflammation and improve drainage 3, 1, 2
• Saline nasal irrigation (high-volume, physiologic or hypertonic): Improves mucociliary clearance and reduces nasal congestion 1, 2
• Analgesics (acetaminophen or ibuprofen): Relieve pain and fever 3, 1
• Adequate hydration 3, 1

Short-term oral corticosteroids may be considered for patients with marked mucosal edema or who fail to respond to initial antibiotic treatment (typical duration 5 days). 3, 1

When to Refer to a Specialist

Refer to otolaryngology, infectious disease, or allergy/immunology for: 3, 1, 2

• No improvement after 7 days of appropriate second-line antibiotic therapy
• Worsening symptoms at any time despite treatment
• Suspected complications (orbital cellulitis, meningitis, brain abscess)
• Recurrent sinusitis (≥3 episodes per year)
• Chronic sinusitis (symptoms >8 weeks)
• Need to clarify allergic or immunologic basis for sinusitis
• Immunocompromised patients

Critical Pitfalls to Avoid

• Do NOT use first-generation cephalosporins (cephalexin, cefadroxil) for sinusitis—they have inadequate coverage against H. influenzae (nearly 50% of strains are β-lactamase producing). 1
• Do NOT use azithromycin or macrolides as first-line therapy—resistance rates exceed 20-25% for both S. pneumoniae and H. influenzae. 1, 2, 6
• Do NOT use trimethoprim-sulfamethoxazole—resistance rates are 50% for S. pneumoniae and 27% for H. influenzae. 3, 1
• Do NOT use clindamycin as monotherapy—it lacks activity against H. influenzae and M. catarrhalis (30-40% failure rate). 1
• Do NOT use plain amoxicillin as first-line therapy given the high prevalence of β-lactamase-producing organisms. 1, 2
• Do NOT reserve fluoroquinolones for routine first-line use in patients without documented β-lactam allergies—this promotes antimicrobial resistance. 3, 1
• Do NOT continue ineffective antibiotics beyond 3-5 days—failure to reassess and switch therapy leads to prolonged illness and potential complications. 1, 2
• Do NOT prescribe antibiotics for viral rhinosinusitis (symptoms <10 days without severe features)—this contributes to antimicrobial resistance without clinical benefit. 1, 2

Special Clinical Situations

Frontal, Ethmoidal, or Sphenoidal Sinusitis

Reserve respiratory fluoroquinolones (levofloxacin or moxifloxacin) for these anatomic locations due to potential for serious complications. 3, 1

Chronic Sinusitis (Symptoms >8 Weeks)

• Intranasal corticosteroids are primary therapy 3, 1
• Daily high-volume saline irrigation 1
• Longer duration antibiotic therapy may be required for chronic infectious sinusitis 3
• Chronic hyperplastic eosinophilic rhinosinusitis does not respond to antibiotics and requires systemic corticosteroids 1

Recurrent Sinusitis (≥3 Episodes Per Year)

Evaluate for underlying risk factors: 3, 1, 2

• Allergic rhinitis
• Immunodeficiency (quantitative immunoglobulin measurement, functional antibody tests, HIV testing)
• Anatomic abnormalities
• Cystic fibrosis (in children with nasal polyps or Pseudomonas colonization)
• Gastroesophageal reflux disease (GERD)