First-Line Treatment for Adult Acute Bacterial Sinusitis with Penicillin Allergy
For an adult with acute bacterial sinusitis and a penicillin allergy, prescribe a respiratory fluoroquinolone—specifically levofloxacin 500 mg once daily for 10–14 days or moxifloxacin 400 mg once daily for 10 days—if the allergy is severe (anaphylaxis, urticaria, angioedema); for non-severe penicillin reactions (mild rash), use a second- or third-generation cephalosporin such as cefuroxime, cefpodoxime, or cefdinir for 10 days. 1, 2
Step 1: Confirm the Diagnosis of Acute Bacterial Sinusitis
Before prescribing any antibiotic, verify that the patient meets at least one of three diagnostic criteria for acute bacterial rhinosinusitis (ABRS): 2
- Persistent symptoms ≥ 10 days without improvement—purulent nasal discharge plus either nasal obstruction or facial pain/pressure/fullness. 1, 2
- Severe symptoms ≥ 3–4 consecutive days—fever ≥ 39 °C (102.2 °F) with purulent nasal discharge and facial pain. 1, 2
- "Double sickening"—initial improvement from a viral upper respiratory infection followed by worsening symptoms within 10 days. 1, 2
Approximately 98–99.5% of acute rhinosinusitis cases are viral and resolve spontaneously within 7–10 days without antibiotics; do not prescribe antibiotics for symptoms lasting < 10 days unless severe features are present. 1, 2
Step 2: Classify the Type of Penicillin Allergy
The choice of antibiotic hinges on whether the patient has a severe (Type I/anaphylactic) versus non-severe (non-Type I) penicillin allergy: 1, 2
Non-Severe Penicillin Allergy (Mild Rash, Delayed Reaction)
- Second- or third-generation cephalosporins are safe and preferred because cross-reactivity with penicillins is negligible (< 1%). 1, 2, 3
- Recommended agents:
- Dosing: Standard adult dosing for 10 days (e.g., cefpodoxime 200 mg twice daily). 2, 4
Severe Penicillin Allergy (Anaphylaxis, Urticaria, Angioedema)
- Respiratory fluoroquinolones are the first-line choice because cephalosporins carry a 1–10% cross-reactivity risk with true IgE-mediated penicillin allergy. 1, 2, 4
- Recommended agents:
- Predicted clinical efficacy: 90–92% against drug-resistant Streptococcus pneumoniae, β-lactamase-producing Haemophilus influenzae, and Moraxella catarrhalis. 1, 2, 5, 4
Step 3: Alternative Option—Doxycycline (Suboptimal but Acceptable)
- Doxycycline 100 mg once daily for 10 days is an acceptable alternative when fluoroquinolones are contraindicated (e.g., pregnancy, tendon disorders, QT prolongation risk) or unavailable. 1, 2, 5
- Predicted efficacy: 77–81% with a 20–25% bacteriologic failure rate due to limited activity against H. influenzae. 1, 2, 5
- Contraindication: Do not use in children < 8 years old (risk of tooth enamel discoloration). 2
Step 4: Antibiotics to Avoid in Penicillin-Allergic Patients
- Macrolides (azithromycin, clarithromycin): Resistance rates exceed 20–25% for both S. pneumoniae and H. influenzae; the American Academy of Pediatrics explicitly contraindicates azithromycin for acute bacterial sinusitis. 1, 2, 5, 4
- Trimethoprim-sulfamethoxazole (Bactrim): Resistance is ≈ 50% in S. pneumoniae and ≈ 27% in H. influenzae. 1, 2
- First-generation cephalosporins (cephalexin, cefadroxil): Inadequate coverage because ≈ 50% of H. influenzae strains produce β-lactamase. 1, 2, 5
Step 5: Treatment Duration and Monitoring
- Standard duration: 10–14 days or until the patient is symptom-free for 7 consecutive days (typically 10–14 days total). 1, 2, 5, 4
- Reassess at 3–5 days: If there is no clinical improvement (persistent purulent drainage, unchanged facial pain, or worsening), switch to a respiratory fluoroquinolone (if not already prescribed) or consider high-dose amoxicillin-clavulanate if the allergy permits. 1, 2
- Reassess at 7 days: Persistent or worsening symptoms warrant confirmation of diagnosis, exclusion of complications (orbital cellulitis, meningitis, intracranial abscess), and consideration of imaging or ENT referral. 1, 2
Step 6: Essential Adjunctive Therapies (Add to All Patients)
- Intranasal corticosteroids (mometasone, fluticasone, or budesonide) twice daily significantly reduce mucosal inflammation and accelerate symptom resolution; supported by strong evidence from multiple randomized controlled trials. 1, 2, 4
- Saline nasal irrigation 2–3 times daily provides symptomatic relief and aids mucus clearance. 1, 2, 4
- Analgesics (acetaminophen or ibuprofen) for pain and fever control. 1, 2, 4
Step 7: When to Refer to Otolaryngology
Refer the patient if any of the following occur: 1, 2, 4
- No improvement after 7 days of appropriate second-line antibiotic therapy.
- Worsening symptoms at any time (increasing facial pain, fever, purulent drainage).
- Signs of complications: severe headache, visual changes, periorbital swelling/erythema, proptosis, diplopia, altered mental status, or cranial nerve deficits.
- Recurrent sinusitis (≥ 3 episodes per year) requiring evaluation for underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities.
Common Pitfalls to Avoid
- Do not assume all penicillin allergies are severe; the majority are non-severe and can safely receive cephalosporins. 1, 2, 3
- Reserve fluoroquinolones for severe penicillin allergy or treatment failure; avoid routine first-line use in non-severe allergy to prevent resistance. 1, 2
- Do not prescribe antibiotics for symptoms < 10 days unless severe criteria (fever ≥ 39 °C with purulent discharge for ≥ 3 consecutive days) are met. 1, 2
- Ensure a minimum 10-day treatment duration for cephalosporins and fluoroquinolones to prevent relapse. 1, 2, 5, 4