In a 73-year-old man with persistent sinus infection despite completing courses of amoxicillin (10 days), amoxicillin‑clavulanate (10 days), and doxycycline (7 days), who now has nasal congestion, rhinorrhea, mild cough, and maxillary sinus pressure, what is the appropriate next step in management?

Stop Antibiotics and Obtain CT Imaging

This patient has failed three courses of antibiotics over 27+ days and now requires CT imaging of the paranasal sinuses to evaluate for chronic rhinosinusitis, anatomic abnormalities, or complications—not another antibiotic trial. 1

Why No More Antibiotics Now

This 73-year-old has completed:

• Amoxicillin × 10 days
• Augmentin (amoxicillin-clavulanate) × 10 days
• Doxycycline × 7 days

He has now received >27 days of antibiotic therapy covering both typical and resistant pathogens. The guidelines are explicit: sinusitis failing to improve after 21-28 days of initial antibiotic treatment requires imaging and specialist evaluation, not empiric continuation of antibiotics 1. His mild, persistent symptoms (nasal congestion, rhinorrhea, mild cough, mild maxillary pressure) without purulent discharge, fever, or severe pain suggest either:

• Chronic rhinosinusitis (symptoms >8 weeks would meet criteria, but he's approaching this threshold) 1
• Non-infectious etiology (allergic rhinitis, non-allergic rhinitis, anatomic obstruction)
• Inadequately treated underlying inflammation
• Nasal polyps or structural abnormalities

The 2025 surgical guideline emphasizes that significant or persistent purulent nasal discharge must be present on examination before prescribing antibacterial therapy for chronic rhinosinusitis 2. Without this finding, antibiotics are not indicated.

Immediate Next Steps

1. Order CT Scan of Paranasal Sinuses

• Coronal cuts with extra views through the ostiomeatal complex 1
• This is the definitive imaging modality to:
  • Confirm chronic rhinosinusitis diagnosis
  • Identify anatomic abnormalities (deviated septum, concha bullosa, ostiomeatal obstruction)
  • Detect nasal polyps
  • Rule out fungal sinusitis, tumors, or other structural pathology

2. Evaluate for Underlying Risk Factors

The guidelines mandate detailed evaluation of underlying causes at this stage 1:

Allergic Rhinitis:

• History of seasonal symptoms, sneezing, itching, eye symptoms
• Consider allergy testing (skin testing or specific IgE) 1, 3

Non-Allergic Rhinitis:

• Vasomotor rhinitis, NARES (non-allergic rhinitis with eosinophilia syndrome)
• Rhinitis medicamentosa (overuse of nasal decongestant sprays)

Anatomic Issues:

• Deviated septum, turbinate hypertrophy (will be visible on CT)

Immunodeficiency (especially in elderly):

• Recurrent infections elsewhere (otitis, bronchitis, pneumonia)
• Consider quantitative immunoglobulins (IgG, IgA, IgM) if history suggests 1

GERD:

• Increasingly recognized contributor to chronic rhinosinusitis 1

3. Symptomatic Management While Awaiting CT

Intranasal Corticosteroids:

• Fluticasone or mometasone nasal spray daily
• Most effective medical therapy for chronic rhinosinusitis 1
• Reduces mucosal inflammation regardless of etiology

Nasal Saline Irrigation:

• High-volume (240 mL) twice daily
• Mechanically clears secretions and reduces inflammation 4

Comfort Measures:

• Adequate hydration
• Warm facial compresses
• Sleeping with head elevated
• Avoid irritants (cigarette smoke, pollution) 1

Analgesics as needed for sinus pressure 4

4. Referral to Otolaryngology or Allergy/Immunology

Indications for specialist referral are clearly met 1:

• Symptoms persisting despite >21 days of antibiotic therapy
• Need for CT interpretation and management planning
• Evaluation for surgical candidacy if medical management fails
• Assessment for allergy, immunodeficiency, or unusual pathogens

The allergist-immunologist can provide:

• Comprehensive allergy evaluation
• Immunodeficiency workup if indicated
• Management of underlying allergic/inflammatory conditions 1

The otolaryngologist can provide:

• Nasal endoscopy to visualize middle meatus, polyps, purulent drainage
• CT interpretation for surgical planning
• Functional endoscopic sinus surgery if indicated 1, 2

When to Consider Additional Antibiotics

Only if CT and/or endoscopy reveal:

• Acute purulent exacerbation with visible purulent discharge on examination 2
• Fungal sinusitis (requires urgent ENT referral—high mortality if untreated) 5
• Complications (orbital cellulitis, intracranial extension)

If antibiotics are needed later, options include:

• Broader-spectrum agents: cefuroxime, cefpodoxime, or respiratory fluoroquinolone (levofloxacin, moxifloxacin) 1
• Consider anaerobic coverage (clindamycin or metronidazole) if chronic infectious sinusitis confirmed 1
• However, recent high-quality evidence shows amoxicillin alone is non-inferior to amoxicillin-clavulanate for acute sinusitis with fewer adverse events 6, 7, so if simple bacterial infection is suspected, amoxicillin remains appropriate

Common Pitfalls to Avoid

Don't prescribe another empiric antibiotic course. This patient has already received appropriate coverage for typical and resistant pathogens. Continuing antibiotics without imaging risks:

• Antibiotic resistance
• Adverse events (C. difficile infection, yeast infections—higher with amoxicillin-clavulanate) 6
• Delayed diagnosis of non-infectious causes
• Missing structural abnormalities requiring surgery

Don't order plain radiographs. They have significant false-positive and false-negative rates 1. CT is the standard for chronic/recurrent sinusitis 1, 4.

Don't assume this is still acute bacterial sinusitis. After 27+ days of symptoms and multiple antibiotic failures, this is either evolving chronic rhinosinusitis or a non-infectious process 1.

Don't delay specialist referral. Guidelines explicitly state that sinusitis persisting despite adequate antibiotic trials requires specialist evaluation 1, 4.

Summary Algorithm

1. Stop antibiotics (adequate trials completed)
2. Order CT paranasal sinuses (coronal with ostiomeatal cuts)
3. Start intranasal corticosteroid + nasal saline irrigation
4. Evaluate for underlying causes: allergic rhinitis, GERD, immunodeficiency
5. Refer to ENT or Allergy/Immunology for definitive management
6. Consider antibiotics only if CT/endoscopy shows acute purulent infection or complications

The goal now is diagnosis and addressing underlying pathology, not empiric antibiotic escalation.