What are the first-line antibiotics and their doses for a patient with sinusitis?

First-Line Antibiotics for Sinusitis and Their Dosages

Amoxicillin is the first-line antibiotic for uncomplicated acute bacterial sinusitis in adults, typically dosed at 500 mg twice daily, with higher doses (875 mg twice daily) recommended for more severe infections. 1

Adult Patients

First-Line Options:

• Amoxicillin: 500 mg twice daily for mild-moderate cases; 875 mg twice daily for more severe cases 1
• Duration of therapy: 10-14 days until the patient is symptom-free for 7 days 2
• For patients with risk factors (recent antibiotic use, daycare attendance), consider high-dose amoxicillin-clavulanate instead 3

For Penicillin-Allergic Patients:

• Cephalosporins (if no history of anaphylaxis to penicillin):
  • Cefuroxime axetil: 250-500 mg twice daily 2, 1
  • Cefpodoxime proxetil: 200 mg twice daily 1
• Macrolides (if true penicillin allergy):
  • Clarithromycin or azithromycin may be prescribed, though resistance rates are higher 2, 4

Pediatric Patients

First-Line Options:

• Amoxicillin: 45 mg/kg/day in 2 divided doses for standard therapy 2
• High-dose amoxicillin: 80-90 mg/kg/day in 2 divided doses (maximum 2g per dose) for areas with high prevalence of resistant S. pneumoniae 2

For Children with Risk Factors:

• Amoxicillin-clavulanate: 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day of clavulanate in 2 divided doses (maximum 2g per dose) 2
• Risk factors include: age <2 years, daycare attendance, recent antibiotic use 2

For Penicillin-Allergic Children:

• Cefpodoxime proxetil: 8 mg/kg/day in two doses 2
• Ceftriaxone: 50 mg/kg as a single dose (IV or IM) for children unable to tolerate oral medication 2

Treatment Failure Protocol

• If no improvement after 3-5 days of initial therapy, switch to a different antibiotic 2, 1
• Second-line options include:
  • High-dose amoxicillin-clavulanate (2000 mg amoxicillin component twice daily) 3, 5
  • Fluoroquinolones (for adults only) with pneumococcal activity like levofloxacin 500 mg once daily 1, 6

Adjunctive Therapies

• Intranasal corticosteroids are recommended as adjuncts to antibiotic therapy 3, 1
• Short-term oral corticosteroids may be considered for patients with marked mucosal edema or who fail to respond to initial treatment 2, 3
• Supportive measures: adequate hydration, analgesics, warm facial packs, and sleeping with head elevated 2

Important Considerations

• Complete the full course of antibiotics even after symptoms improve to prevent relapse 2
• Recent research suggests that high-dose amoxicillin-clavulanate may not provide significant benefits over standard-dose therapy but may increase adverse effects like diarrhea 7
• The diagnosis of bacterial sinusitis should be confirmed before initiating antibiotics to avoid unnecessary treatment 8
• For sphenoid or frontal sinusitis, which can have more serious complications, consider more aggressive therapy or hospitalization 9

Remember that local antibiotic resistance patterns should guide therapy, particularly for S. pneumoniae, H. influenzae, and M. catarrhalis, which are the most common pathogens in acute bacterial sinusitis 2, 4.