What is the best antibiotic (abx) for acute bacterial sinusitis?

Best Antibiotic for Acute Bacterial Sinusitis

Amoxicillin-clavulanate is the recommended first-line antibiotic for acute bacterial sinusitis, with a dosage of 875/125 mg twice daily for 5-7 days in adults. 1

Diagnosis of Acute Bacterial Sinusitis

Before initiating antibiotics, confirm the diagnosis based on one of these clinical presentations:

• Persistent symptoms: nasal discharge or cough for >10 days without improvement
• Severe symptoms: high fever (>39°C/102.2°F) with purulent nasal discharge or facial pain for ≥3 consecutive days
• Worsening symptoms: initial improvement followed by worsening nasal discharge, cough, or fever 1

Antibiotic Treatment Algorithm

First-Line Therapy

• Amoxicillin-clavulanate 875/125 mg twice daily for 5-7 days 1
  • Provides coverage against common respiratory pathogens including beta-lactamase producing H. influenzae
  • Preferred over amoxicillin alone due to increasing prevalence of beta-lactamase producing organisms

Alternative Options (for penicillin-allergic patients)

1. Cephalosporins (if non-anaphylactic penicillin allergy):

   • Cefuroxime: 250-500 mg twice daily for 5-7 days
   • Cefpodoxime: 200-400 mg twice daily for 5-7 days
   • Cefdinir: 300-600 mg twice daily for 5-7 days 1

2. Respiratory fluoroquinolones (for severe penicillin allergy):

   • Levofloxacin: 750 mg once daily for 5 days or 500 mg once daily for 10-14 days 1, 2
   • Moxifloxacin: 400 mg once daily for 5-7 days 1

Clinical Evidence Supporting Recommendations

Amoxicillin-clavulanate has demonstrated high efficacy in treating acute bacterial sinusitis. The American Academy of Pediatrics and European Society of Clinical Microbiology and Infectious Diseases both recommend it as first-line therapy 1.

The FDA has approved levofloxacin for acute bacterial sinusitis at either 750 mg once daily for 5 days or 500 mg once daily for 10-14 days, with clinical success rates of 91.4% and 88.6% respectively 2. However, fluoroquinolones should be reserved for patients with penicillin allergies or treatment failures due to concerns about antimicrobial resistance and side effects.

Treatment Duration

The optimal duration for antibiotic therapy is 5-7 days for most patients 1. Longer courses (10-14 days) may be considered for patients with severe symptoms, immunocompromise, or complications.

Assessment of Treatment Response

Patients should be assessed for clinical improvement within 72 hours of starting antibiotics. If no improvement is seen, consider:

• Switching to a broader-spectrum antibiotic
• Immediate specialist referral if signs of complications are present 1

Adjunctive Treatments

In addition to antibiotics, consider:

• Intranasal corticosteroids
• Saline nasal irrigation
• Oral decongestants (short-term use)
• Acetaminophen or ibuprofen for pain and fever 1

When to Refer

Consider referral to an otolaryngologist if:

• Symptoms persist despite appropriate antibiotic therapy
• Symptoms last beyond 3 weeks despite treatment
• Signs of complicated sinusitis (orbital involvement, severe pain, persistent fever) 1

Common Pitfalls to Avoid

1. Using cephalexin (Keflex) as first-line treatment - inadequate coverage against H. influenzae 1
2. Treating viral rhinosinusitis with antibiotics - most cases of rhinosinusitis are viral
3. Failing to assess for treatment response within 72 hours
4. Not considering local resistance patterns when selecting antibiotics

Proper diagnosis and appropriate antibiotic selection are crucial for effective management of acute bacterial sinusitis while minimizing antibiotic resistance.