What is the recommended antibiotic for treating sinusitis suspected to be of bacterial cause following a viral illness?

Antibiotic Treatment for Bacterial Sinusitis Following Viral Illness

Amoxicillin-clavulanate is the recommended first-line antibiotic for treating suspected bacterial sinusitis following a viral illness. 1

Diagnosis of Bacterial Sinusitis

Bacterial sinusitis should be suspected when:

• Symptoms persist for more than 10 days without clinical improvement 1
• Symptoms are severe (fever >39°C, purulent nasal discharge, or facial pain lasting for >3 consecutive days) 1
• Symptoms worsen after an initial period of improvement ("double sickening") for more than 3 days 1

First-Line Antibiotic Treatment

Adults:

• Amoxicillin-clavulanate is the preferred agent 1, 2
  • Standard dosing: 875mg/125mg twice daily for 7-10 days 2, 3
  • High-dose amoxicillin-clavulanate may be considered in areas with high prevalence of resistant S. pneumoniae, but recent research shows no significant benefit over standard dosing 4

Children:

• Amoxicillin-clavulanate (80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day of clavulanate in 2 divided doses) 1
• Particularly important for children <2 years, attending childcare, or with recent antibiotic use 1

Alternative Antibiotics (for penicillin allergy)

• Doxycycline (for adults) 1
• Respiratory fluoroquinolones (levofloxacin or moxifloxacin) - reserve for patients with risk of complications or treatment failure 1, 2, 5
• Cephalosporins (cefuroxime, cefpodoxime, cefdinir) for non-Type I hypersensitivity reactions 1, 2, 6

Treatment Duration

• Standard treatment duration is 7-10 days 1, 2
• Continue until symptoms are improved and then for an additional 7 days 7

Important Considerations

• Acute bacterial rhinosinusitis is often preceded by viral upper respiratory infection, with fewer than 2% of viral URIs complicated by bacterial sinusitis 1
• Most patients diagnosed with acute rhinosinusitis have more adverse effects than benefits from antibiotics (number needed to treat = 18, number needed to harm = 8) 1
• Nasal corticosteroids may be beneficial as adjunctive therapy to reduce symptoms in post-viral rhinosinusitis 1

When to Consider Watchful Waiting

• The American Academy of Otolaryngology–Head and Neck Surgery recommends watchful waiting as initial management for uncomplicated bacterial sinusitis 1
• Supportive care includes adequate hydration, analgesics, warm facial packs, and nasal saline irrigation 1

When to Reassess or Consider Alternative Treatment

• If no improvement after 3-5 days of initial antibiotic therapy 1
• For poor response to initial therapy, consider broader-spectrum antibiotics or consultation with specialist 1
• Consider referral to specialist for patients with recurrent episodes (typically 3 or more per year) 1

Common Pathogens

• Streptococcus pneumoniae (approximately 30% of cases) 1
• Haemophilus influenzae (approximately 30% of cases) 1
• Moraxella catarrhalis (approximately 10% of cases) 1

Remember that acute rhinosinusitis is usually a self-limited illness, and antibiotics should be prescribed only when bacterial infection is strongly suspected based on clinical criteria 1.