What is the recommended treatment for an adult patient with bacterial sinusitis who is allergic to penicillins (PCNs) and cephalosporins?

Recommended Treatment for Bacterial Sinusitis with Penicillin and Cephalosporin Allergy

For adult patients with bacterial sinusitis who are allergic to both penicillins and cephalosporins, respiratory fluoroquinolones—specifically levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10 days—are the first-line treatment choice. 1, 2, 3

Why Fluoroquinolones Are the Optimal Choice

Respiratory fluoroquinolones provide 90-92% predicted clinical efficacy against all major sinusitis pathogens, including drug-resistant Streptococcus pneumoniae (including multi-drug resistant strains), β-lactamase-producing Haemophilus influenzae, and Moraxella catarrhalis. 1, 3, 4

Specific Dosing Options:

• Levofloxacin: 500 mg once daily for 10-14 days 1, 2, 3
• Moxifloxacin: 400 mg once daily for 10 days 1, 2, 3, 4

Moxifloxacin is FDA-approved specifically for acute bacterial sinusitis and provides 99% coverage against S. pneumoniae, 95-100% coverage against H. influenzae, and 100% coverage against M. catarrhalis. 3, 4

What NOT to Use

Avoid these antibiotics due to high resistance rates or inadequate coverage:

• Azithromycin and macrolides: Explicitly contraindicated due to resistance rates exceeding 20-25% for both S. pneumoniae and H. influenzae 1, 2, 3
• Trimethoprim-sulfamethoxazole: 50% resistance rate for S. pneumoniae and 27% for H. influenzae 1, 2
• Doxycycline: Has a 20-25% predicted bacteriologic failure rate and limited activity against H. influenzae 1, 2
• Clindamycin monotherapy: Lacks activity against H. influenzae and M. catarrhalis, covering only 60-70% of pathogens 1, 2

Confirm the Diagnosis First

Only prescribe antibiotics when acute bacterial sinusitis is confirmed by one of three clinical patterns: 1, 2

1. Persistent symptoms ≥10 days without improvement (nasal discharge, congestion, facial pain)
2. Severe symptoms for ≥3 consecutive days (fever ≥39°C with purulent nasal discharge)
3. "Double sickening": Worsening after initial improvement from a viral URI

Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics. 1

Treatment Monitoring and Follow-Up

Reassess at 3-5 days: 1, 2, 3

• Expect reduction in fever, facial pain, and purulent discharge
• If no improvement, re-evaluate diagnosis or consider complications
• Switch antibiotics only if bacterial sinusitis is confirmed

Reassess at 7 days: 1, 3

• If symptoms persist or worsen, reconfirm diagnosis
• Consider CT imaging or ENT referral if no improvement after 7 days of appropriate therapy

Essential Adjunctive Therapies

Add these to enhance symptom resolution regardless of antibiotic choice: 1, 2

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily): Reduce mucosal inflammation with strong evidence from multiple RCTs 1
• Saline nasal irrigation: Provides symptomatic relief and removes mucus 1
• Analgesics (acetaminophen or NSAIDs): For pain and fever management 1
• Adequate hydration and warm facial packs 1

Critical Pitfalls to Avoid

Never use fluoroquinolones in patients without documented β-lactam allergies—this promotes antimicrobial resistance and should be reserved specifically for patients with true allergies or treatment failures. 1, 2

Do not prescribe antibiotics for symptoms lasting <10 days unless severe symptoms are present (fever ≥39°C with purulent discharge for ≥3 consecutive days). 1

Avoid waiting beyond 7 days to change therapy in non-responders—the 3-5 day reassessment is specifically designed to catch early treatment failures. 1

When to Refer or Escalate

Refer to ENT or consider hospitalization if: 1, 3

• No improvement after 7 days of appropriate fluoroquinolone therapy
• Worsening symptoms at any time
• Warning signs of complications: proptosis, visual changes, severe headache, altered mental status, periorbital edema/erythema, or abnormal extraocular movements 3
• Recurrent sinusitis (≥3 episodes per year) requiring evaluation for underlying causes 1