What is the first line antibiotic for acute bacterial sinusitis?

First Line Antibiotic Treatment for Acute Bacterial Sinusitis

Amoxicillin is the first-line antibiotic of choice for uncomplicated acute bacterial sinusitis in situations where antimicrobial resistance is not suspected. 1

Treatment Algorithm for Acute Bacterial Sinusitis

Standard First-Line Therapy

• Amoxicillin at standard dose (45 mg/kg/day in 2 divided doses for children; 500 mg twice daily for adults) is recommended as first-line treatment for uncomplicated acute bacterial sinusitis 1
• This recommendation is based on amoxicillin's effectiveness, safety, acceptable taste, low cost, and relatively narrow microbiologic spectrum 1

High-Risk Situations Requiring Alternative First-Line Therapy

Consider high-dose amoxicillin or amoxicillin-clavulanate in the following situations:

• In communities with high prevalence of nonsusceptible S. pneumoniae (>10%) 1
• Patients younger than 2 years 1
• Patients attending child care 1
• Patients who have received antibiotics within the previous 4-6 weeks 1
• Patients with moderate to severe illness 1

In these cases, use:

• High-dose amoxicillin (80-90 mg/kg/day in 2 divided doses for children; maximum 2g per dose) 1
• Amoxicillin-clavulanate (high-dose: 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day of clavulanate in 2 divided doses for children; 875/125 mg twice daily for adults) 1

For Penicillin-Allergic Patients

• Cefdinir, cefuroxime, or cefpodoxime are appropriate alternatives 1, 2
• Recent publications indicate that the risk of serious allergic reaction to second- and third-generation cephalosporins in patients with penicillin allergy appears to be minimal 1
• For patients with severe penicillin allergy, consider clarithromycin or azithromycin, though be aware of increasing resistance patterns 1, 3, 2

Special Situations

• For patients who are vomiting, unable to tolerate oral medication, or unlikely to adhere to initial doses:
  • Ceftriaxone (50 mg/kg single dose IV/IM for children) can be used, followed by oral therapy if clinical improvement is observed at 24 hours 1
  • Ceftriaxone is effective against 95-100% of the major bacterial pathogens involved in acute bacterial sinusitis 1

Microbiology and Resistance Patterns

• The predominant pathogens in acute bacterial sinusitis are:

  • Streptococcus pneumoniae (approximately 30% of cases) 1, 3
  • Haemophilus influenzae (approximately 30% of cases) 1, 3
  • Moraxella catarrhalis (approximately 10% of cases) 1, 3

• Resistance patterns to consider:

  • 10-15% of S. pneumoniae isolates nationally are nonsusceptible to penicillin, with some areas reporting resistance as high as 50-60% 1
  • 10-42% of H. influenzae and nearly 100% of M. catarrhalis are β-lactamase positive and nonsusceptible to amoxicillin 1

Duration of Treatment

• The optimal duration of antimicrobial therapy has not received systematic study 1
• Recommendations generally range from 7-10 days for most cases 1
• Some experts recommend continuing treatment until the patient is free of symptoms and then for an additional 7 days 1, 3

Common Pitfalls and Caveats

• Avoid inappropriate antibiotic use: Do not prescribe antibiotics for viral upper respiratory infections 1
• Recognize resistance patterns: Be familiar with local patterns of antimicrobial susceptibility 1
• Consider treatment failure: If no clinical response occurs within 72 hours, reevaluate and consider switching to a second-line antibiotic 1, 2
• Avoid ineffective antibiotics: Due to resistance patterns, trimethoprim/sulfamethoxazole and azithromycin should not be used as first-line therapy for acute bacterial sinusitis 1
• Distinguish bacterial from viral sinusitis: Bacterial sinusitis is characterized by persistent symptoms (>10 days), severe symptoms, or worsening symptoms after initial improvement 1, 3