What is the recommended treatment for acute bacterial sinusitis in an otherwise healthy adult without drug allergies?

Management of Acute Sinus Infection in Otherwise Healthy Adults

Confirm the Diagnosis Before Prescribing Antibiotics

Most acute sinus symptoms are viral and resolve spontaneously within 7–10 days; antibiotics should be reserved for confirmed bacterial infection. 1, 2

• Diagnose acute bacterial rhinosinusitis only when at least one of the following patterns is present:

  • Persistent symptoms ≥10 days with purulent nasal discharge plus either nasal obstruction or facial pain/pressure/fullness. 1, 2
  • Severe symptoms ≥3–4 consecutive days with fever ≥39°C (102.2°F), 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, 3

• Do not prescribe antibiotics for symptoms lasting <10 days unless the severe pattern (high fever with purulent discharge for ≥3 days) is present. Approximately 98–99.5% of acute rhinosinusitis cases are viral. 1, 4

• Imaging (X-ray or CT) is not recommended for uncomplicated cases; up to 87% of viral upper respiratory infections show sinus abnormalities on imaging, leading to unnecessary interventions. 1, 2

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First-Line Antibiotic Therapy

Amoxicillin-clavulanate 875 mg/125 mg orally twice daily for 5–10 days is the preferred first-line regimen, providing 90–92% predicted clinical efficacy against the three major pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis). 1, 2

• Treatment duration: Continue for 5–10 days or until the patient is symptom-free for 7 consecutive days (typically 10–14 days total). 1, 4

• Recent evidence supports shorter 5–7 day courses with comparable efficacy and fewer adverse effects. 1

• High-dose regimen (2 g amoxicillin/125 mg clavulanate twice daily) is indicated when any of the following risk factors are present: recent antibiotic use within the past 4–6 weeks, age >65 years, daycare exposure, moderate-to-severe symptoms, comorbidities (diabetes, chronic organ disease), or immunocompromised state. 1

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Alternatives for Penicillin Allergy

Non-Severe (Non-Type I) Penicillin Allergy

Use a second- or third-generation cephalosporin for 10 days; cross-reactivity with penicillins is negligible (<1%). 1, 2

• Options include: cefuroxime-axetil, cefpodoxime-proxetil, cefdinir, or cefprozil. 1, 3

Severe (Type I/Anaphylactic) Penicillin Allergy

Respiratory fluoroquinolones are the preferred agents, providing 90–92% predicted efficacy against multidrug-resistant S. pneumoniae and β-lactamase-producing organisms. 1, 5

• Levofloxacin 500 mg once daily for 10–14 days 1, 5

• Moxifloxacin 400 mg once daily for 10 days 1

• Reserve fluoroquinolones for severe penicillin allergy or documented treatment failure to limit resistance development; they should not be used as routine first-line therapy. 1

Suboptimal Alternative

Doxycycline 100 mg once daily for 10 days is acceptable only when cephalosporins and fluoroquinolones are contraindicated (e.g., pregnancy, tendon disorders). It has lower predicted efficacy (77–81%) and a 20–25% bacteriologic failure rate due to limited activity against H. influenzae. 1

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Essential Adjunctive Therapies (Add to All Patients)

Intranasal corticosteroids (mometasone, fluticasone, or budesonide) twice daily significantly reduce mucosal inflammation and accelerate symptom resolution; this recommendation is 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

• Decongestants (oral or topical) may be used; limit topical agents to ≤3 days to avoid rebound congestion. 1, 2

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Watchful Waiting Strategy

For uncomplicated acute bacterial sinusitis with reliable follow-up, initial observation without antibiotics is appropriate. 1, 2

• Initiate antibiotics only if there is no improvement by day 7 or if symptoms worsen at any time. 1, 2

• The number needed to treat (NNT) with antibiotics is 10–15 to achieve one additional cure compared with placebo, reflecting the high spontaneous recovery rate. 1, 4

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Monitoring and Reassessment Protocol

Early Reassessment (Days 3–5)

If there is no clinical improvement (persistent purulent drainage, unchanged facial pain, or worsening), switch immediately to high-dose amoxicillin-clavulanate (2 g/125 mg twice daily) or a respiratory fluoroquinolone (levofloxacin or moxifloxacin). 1, 4

• Do not extend the initial antibiotic beyond 3–5 days without improvement; early discontinuation prevents unnecessary drug exposure and bacterial proliferation. 1

Day 7 Reassessment

Persistent or worsening symptoms warrant:

1. Confirmation of diagnosis
2. Exclusion of complications (orbital cellulitis, meningitis, intracranial abscess)
3. Imaging (CT) only if complications are suspected
4. Referral to otolaryngology 1, 4

Expected Timeline of Recovery

• Noticeable improvement should occur within 3–5 days of appropriate antibiotic therapy. 1, 4
• Complete resolution typically occurs by 10–14 days or when the patient is symptom-free for 7 consecutive days. 1, 4
• Only 30–41% of patients show improvement by days 3–5; zero improvement at this point indicates treatment failure. 1

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Antibiotics to Avoid

Macrolides (azithromycin, clarithromycin) should never be used; resistance rates are 20–25% for S. pneumoniae and H. influenzae. 1, 3

Trimethoprim-sulfamethoxazole exhibits ≈50% resistance in S. pneumoniae and ≈27% in H. influenzae. 1

First-generation cephalosporins (e.g., cephalexin) are inadequate because ≈50% of H. influenzae strains produce β-lactamase. 1

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Referral to Otolaryngology

Refer immediately if any of the following occur:

• No improvement after 7 days of appropriate second-line antibiotic therapy 1, 4
• Worsening symptoms at any point (increasing facial pain, fever, purulent drainage) 1, 4
• Suspected complications: severe headache, visual changes, periorbital swelling/erythema, proptosis, diplopia, altered mental status, or cranial nerve deficits 1, 4
• Recurrent sinusitis (≥3 episodes per year) requiring evaluation for underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities 6, 1

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Common Pitfalls to Avoid

• Do not prescribe antibiotics based solely on purulent nasal discharge; this finding occurs in viral illnesses. 1, 4

• Ensure adequate treatment duration (≥5 days for adults) to prevent relapse. 1

• Gastrointestinal adverse effects with amoxicillin-clavulanate are common: diarrhea occurs in 40–43% of patients, with severe diarrhea in 7–8%. 1, 4

• Do not use fluoroquinolones as first-line therapy in patients without documented β-lactam allergy to limit resistance development. 1