What are the first and second line treatments for a patient with acute bacterial sinusitis?

First and Second Line Treatment for Acute Bacterial Sinusitis

First-Line Treatment

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line antibiotic for acute bacterial sinusitis in adults. 1, 2, 3

Standard First-Line Regimen

• Amoxicillin-clavulanate 875 mg/125 mg twice daily is preferred over plain amoxicillin due to increasing prevalence of β-lactamase-producing organisms (H. influenzae and M. catarrhalis) 1, 2, 3
• Plain amoxicillin 500 mg twice daily (mild disease) or 875 mg twice daily (moderate disease) remains acceptable for uncomplicated cases without recent antibiotic exposure 1, 2, 3
• Treatment duration: 5-10 days, or until symptom-free for 7 days (typically 10-14 days total) 1, 2, 3

High-Dose Regimen for High-Risk Patients

• High-dose amoxicillin-clavulanate (2 g amoxicillin/125 mg clavulanate twice daily) should be used for patients with: 1, 2
  • Recent antibiotic use within the past month
  • Age >65 years
  • Moderate-to-severe symptoms
  • Comorbid conditions or immunocompromised state

First-Line for Penicillin-Allergic Patients

• Second-generation cephalosporins: cefuroxime-axetil 1, 2, 3
• Third-generation cephalosporins: cefpodoxime-proxetil, cefdinir, or cefprozil 1, 2, 3
• The risk of cross-reactivity with second- and third-generation cephalosporins in penicillin-allergic patients is negligible 1

Second-Line Treatment

Respiratory fluoroquinolones (levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10 days) are the preferred second-line agents after first-line treatment failure. 1, 4

When to Switch to Second-Line

• Reassess at 3-5 days: if no improvement, switch antibiotics immediately 1, 2, 3
• Definitive assessment at 7 days: if symptoms persist or worsen, confirm diagnosis and switch to second-line therapy 1, 2

Second-Line Options

• Levofloxacin 500 mg once daily for 10-14 days provides 90-92% predicted clinical efficacy against drug-resistant S. pneumoniae and β-lactamase-producing organisms 1, 4
• Moxifloxacin 400 mg once daily for 10 days offers equivalent coverage 1
• High-dose amoxicillin-clavulanate (if not used as first-line): 2 g amoxicillin/125 mg clavulanate twice daily 1, 2
• Third-generation cephalosporins (cefpodoxime, cefdinir) provide superior activity against H. influenzae but have limitations against drug-resistant S. pneumoniae 1

Second-Line for Severe Penicillin Allergy

• Respiratory fluoroquinolones (levofloxacin or moxifloxacin) are the primary option for patients with documented severe penicillin and cephalosporin allergies 1, 4
• Doxycycline 100 mg once daily for 10 days is an acceptable but suboptimal alternative with 77-81% predicted efficacy (compared to 90-92% for fluoroquinolones) 1

Critical Diagnostic Criteria Before Prescribing Antibiotics

Antibiotics should only be prescribed when acute bacterial sinusitis is confirmed by one of three patterns: 1, 2, 3

1. Persistent symptoms ≥10 days without clinical improvement
2. Severe symptoms (fever ≥39°C with purulent nasal discharge) for ≥3 consecutive days
3. "Double sickening" - worsening symptoms after initial improvement from a viral URI

Essential Adjunctive Therapies

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily) reduce mucosal inflammation and improve symptom resolution 1, 2, 3
• Saline nasal irrigation provides symptomatic relief 1, 2, 3
• Analgesics (acetaminophen or NSAIDs) for pain management 1, 2, 3
• Decongestants (systemic or topical) for symptomatic relief, but topical decongestants should not be used >3 days due to risk of rhinitis medicamentosa 2

What NOT to Use

• Azithromycin and other macrolides should not be used as first-line therapy due to resistance rates of 20-25% for both S. pneumoniae and H. influenzae 1, 5
• First-generation cephalosporins (cephalexin, cefadroxil) have inadequate coverage against H. influenzae and should not be used 1
• Trimethoprim-sulfamethoxazole has high resistance rates (50% for S. pneumoniae, 27% for H. influenzae) 1

Critical Pitfalls to Avoid

• Do not prescribe antibiotics for symptoms <10 days unless severe symptoms are present (fever ≥39°C with purulent discharge for ≥3 consecutive days) 1, 2
• Reserve fluoroquinolones appropriately - do not use as first-line therapy in patients without documented β-lactam allergies to prevent resistance development 1, 4
• Reassess at 3-5 days - waiting beyond 7 days to change therapy in non-responders delays effective treatment 1, 2
• Ensure adequate treatment duration - minimum 5 days, typically 7-10 days to prevent relapse 1, 2, 6

Watchful Waiting Option

• 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 if symptoms worsen at any time 1, 2