What is the appropriate first‑line antibiotic for an elderly man with acute sinusitis and acute bronchitis, assuming no penicillin allergy and adequate renal function?

Antibiotic Selection for Elderly Man with Sinusitis and Bronchitis

For an elderly man with acute sinusitis and acute bronchitis, amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line antibiotic, given his age >65 years places him at higher risk for resistant organisms. 1, 2

Why Amoxicillin-Clavulanate is Preferred in This Patient

• Age >65 years is a specific risk factor that prompts clinicians to use amoxicillin-clavulanate instead of plain amoxicillin, as outlined in the American Academy of Otolaryngology-Head and Neck Surgery guidelines 1
• The clavulanate component provides essential coverage against β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis, which account for 30-40% of isolates in respiratory infections 2, 3
• This regimen achieves 90-92% predicted clinical efficacy against the major pathogens causing both sinusitis and bronchitis 2

Confirming the Diagnosis Before Treatment

For sinusitis, antibiotics should only be prescribed when the patient meets one of three criteria 1, 2:

• Persistent symptoms ≥10 days without improvement (purulent nasal discharge with obstruction or facial pain/pressure)
• Severe symptoms for ≥3-4 consecutive days (fever ≥39°C with purulent discharge)
• "Double sickening" (worsening after initial improvement from a viral URI)

For bronchitis, the diagnosis is primarily clinical, though the presence of at least two Anthonisen criteria suggests bacterial origin 1:

• Increased volume of expectoration
• Increased purulence of expectoration
• Increased dyspnea

Treatment Duration and Monitoring

• Standard duration is 5-10 days, with most guidelines recommending treatment until symptom-free for 7 consecutive days (typically 10-14 days total) 1, 2
• Shorter 5-7 day courses have comparable efficacy with fewer adverse effects for uncomplicated cases 1, 2
• Reassess at 3-5 days: if no improvement, switch to a respiratory fluoroquinolone (levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily) 1, 2
• Reassess at 7 days: if symptoms persist or worsen, reconfirm diagnosis and consider complications 1, 2

Essential Adjunctive Therapies (Add to All Patients)

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily) reduce mucosal inflammation in sinusitis and improve symptom resolution, supported by multiple randomized controlled trials 1, 2
• Saline nasal irrigation 2-3 times daily provides symptomatic relief and aids mucus clearance 1, 2
• Analgesics (acetaminophen or ibuprofen) for pain and fever control 1, 2
• Adequate hydration and rest 1

Alternative Options for Penicillin Allergy

If the patient has a documented penicillin allergy:

• Non-severe (non-Type I) allergy: use a second- or third-generation cephalosporin (cefuroxime-axetil, cefpodoxime-proxetil, or cefdinir) for 10 days, as cross-reactivity is negligible 1, 2
• Severe (Type I/anaphylactic) allergy: use a respiratory fluoroquinolone (levofloxacin 500 mg once daily for 10-14 days or moxifloxacin 400 mg once daily for 10 days) 1, 2
• Doxycycline 100 mg once daily for 10 days is an acceptable but suboptimal alternative with 77-81% predicted efficacy (compared to 90-92% for first-line agents) 1, 2

Critical Pitfalls to Avoid

• Do not use azithromycin or other macrolides as first-line therapy due to resistance rates of 20-25% for both S. pneumoniae and H. influenzae 1, 2
• Do not use trimethoprim-sulfamethoxazole due to 50% resistance in S. pneumoniae and 27% in H. influenzae 1, 2
• Do not use first-generation cephalosporins (cephalexin) due to inadequate coverage against H. influenzae 1, 2
• Do not prescribe antibiotics for symptoms <10 days unless severe features are present (fever ≥39°C with purulent discharge for ≥3 consecutive days) 1, 2
• Gastrointestinal adverse effects are more common with amoxicillin-clavulanate (diarrhea in 40-43% of patients, severe in 7-8%), so counsel the patient accordingly 2

When to Refer or Escalate Care

• No improvement after 7 days of appropriate second-line antibiotic therapy 1, 2
• Worsening symptoms at any time during treatment 1, 2
• Suspected complications (orbital cellulitis, meningitis, severe headache, visual changes, altered mental status) 1, 2
• Recurrent sinusitis (≥3 episodes per year) requiring evaluation for underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities 1, 4