Initial Antibiotic Treatment for Sinusitis
Amoxicillin is the first-line antibiotic treatment for uncomplicated acute bacterial sinusitis in both children and adults due to its effectiveness, safety, acceptable taste, low cost, and relatively narrow microbiologic spectrum. 1, 2
Pathogens in Sinusitis
- Streptococcus pneumoniae and Haemophilus influenzae each account for approximately 30% of acute bacterial sinusitis cases in children, while Moraxella catarrhalis is responsible for about 10% 1
- In adults, the predominant bacterial species are the same: S. pneumoniae, H. influenzae, and M. catarrhalis 3, 4
- Anaerobic bacteria and Staphylococcus aureus are more common in chronic sinusitis 4
First-Line Treatment
- For uncomplicated acute bacterial sinusitis in patients who have not received antibiotics in the previous 4-6 weeks:
- Standard-dose amoxicillin (45 mg/kg/day in 2 divided doses for children; 1.5-4 g/day for adults) for 10-14 days 1, 2
- In communities with high prevalence of nonsusceptible S. pneumoniae (>10%), high-dose amoxicillin (80-90 mg/kg/day in 2 divided doses for children; maximum 2g per dose) is recommended 1
Alternative First-Line Options for Penicillin-Allergic Patients
- Doxycycline (for adults) 1
- Respiratory fluoroquinolones (levofloxacin or moxifloxacin) for adults with moderate disease or penicillin allergy 1, 5
- Second or third-generation cephalosporins such as cefuroxime axetil, cefpodoxime proxetil, or cefdinir (if no immediate-type hypersensitivity to penicillin) 1, 6
Second-Line Treatment
- For patients who fail to improve after 72 hours of initial therapy or those at high risk for resistant organisms:
- Amoxicillin-clavulanate (high-dose: 90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day of clavulanate for children; 4g/250mg per day for adults) 1
- Consider amoxicillin-clavulanate instead of amoxicillin in patients with:
- Antibiotic use in the past month
- Close contact with treated individuals or healthcare environments
- High prevalence of resistant bacteria in the community
- Age younger than 2 years or attendance at childcare 1
Risk Factors for Resistant Organisms
- Attendance at childcare 1
- Receipt of antimicrobial treatment within the previous 30 days 1
- Age younger than 2 years 1
- Geographic regions with high endemic rates of penicillin-nonsusceptible S. pneumoniae 1
- Severe infection with systemic toxicity 1
- Age over 65 years 1
Duration of Treatment
- Standard duration is 10-14 days for acute bacterial sinusitis 1, 3
- Some experts recommend treating until the patient is symptom-free plus an additional 7 days 3
- Shorter courses (5-7 days) may be equally effective with fewer side effects, especially for milder cases 1
Common Pitfalls and Caveats
- Failure to distinguish between viral and bacterial sinusitis can lead to unnecessary antibiotic use 3
- Not considering local resistance patterns when selecting initial therapy 1
- Inadequate dosing of amoxicillin in areas with high prevalence of resistant S. pneumoniae 1
- Not reassessing treatment response after 72 hours to determine if therapy change is needed 1, 7
- Using antibiotics with limited coverage against the common pathogens (particularly S. pneumoniae) 1, 4
Special Considerations
- For patients with moderate to severe illness, consider high-dose amoxicillin-clavulanate or respiratory fluoroquinolones (in adults) 1
- A single 50 mg/kg dose of ceftriaxone (IV or IM) can be used for children who are vomiting, unable to tolerate oral medication, or unlikely to adhere to initial doses 1
- In adults with sinusitis who fail to respond to initial therapy, respiratory fluoroquinolones may be appropriate as second-line agents 1, 5