What is the treatment for acute bacterial sinusitis?

Treatment for Acute Bacterial Sinusitis

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-7 days is the preferred first-line treatment for adults with acute bacterial sinusitis, providing superior coverage against β-lactamase-producing organisms compared to amoxicillin alone. 1, 2

Confirming Bacterial vs Viral Sinusitis First

Before prescribing antibiotics, confirm one of three diagnostic patterns 1:

• Persistent symptoms ≥10 days without improvement (nasal discharge, congestion, facial pain/pressure) 1
• Severe onset with high fever ≥39°C (102°F) plus purulent nasal discharge or facial pain for ≥3-4 consecutive days 1
• "Double sickening" - worsening symptoms after initial improvement from a viral URI lasting 5-6 days 1

Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics 3. Prescribing antibiotics before 10 days (unless severe symptoms present) contributes to unnecessary adverse effects and antimicrobial resistance 3.

First-Line Antibiotic Treatment

Adults

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-7 days is recommended over amoxicillin alone due to increasing prevalence of β-lactamase-producing Haemophilus influenzae (20%) and Moraxella catarrhalis (50-70%) 1, 4, 2. The clavulanate component specifically targets these resistant organisms 3.

For uncomplicated cases without recent antibiotic exposure, plain amoxicillin remains acceptable 3, 2:

• 500 mg twice daily for mild disease 3
• 875 mg twice daily for moderate disease 3

Treatment duration is 5-7 days for adults until symptom-free for 7 days 1, 2. Shorter 5-7 day courses have comparable efficacy with fewer side effects compared to traditional 10-14 day regimens 1, 2.

Pediatric Patients

Standard therapy: Amoxicillin 45 mg/kg/day in 2 divided doses for children without recent antibiotic use 3, 2

High-dose therapy (for high-risk children): Amoxicillin-clavulanate 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses 1, 3, 2

High-risk factors include 3:

• Age <2 years
• Daycare attendance
• Antibiotic use within past 4-6 weeks
• Geographic areas with high prevalence of resistant Streptococcus pneumoniae

Treatment duration for children is 10-14 days 1, 2.

Penicillin-Allergic Patients

Non-Anaphylactic Allergy (Rash, Mild Reactions)

Second- or third-generation cephalosporins are safe and appropriate - the risk of cross-reactivity with penicillin allergy is negligible 3, 4, 2. Recent evidence demonstrates the risk of serious allergic reactions to second- and third-generation cephalosporins in penicillin-allergic patients is almost nil 2.

Recommended options 1, 3, 4:

• Cefuroxime-axetil (second-generation)
• Cefpodoxime-proxetil (third-generation, superior activity against H. influenzae)
• Cefdinir (third-generation)

Severe Beta-Lactam Allergy (Anaphylaxis)

Respiratory fluoroquinolones are the treatment of choice 3:

• Levofloxacin 500 mg once daily for 10-14 days 3
• Moxifloxacin 400 mg once daily for 10 days 3

These provide 90-92% predicted clinical efficacy against drug-resistant S. pneumoniae and β-lactamase-producing organisms 3.

What NOT to Use in Penicillin-Allergic Patients

Azithromycin and other macrolides are explicitly contraindicated as first-line therapy due to resistance rates of 20-25% for both S. pneumoniae and H. influenzae 3, 5. The American Academy of Pediatrics explicitly states azithromycin should not be used to treat acute bacterial sinusitis in persons with penicillin hypersensitivity due to resistance patterns 3.

Trimethoprim-sulfamethoxazole should not be used due to high resistance rates of 50% for S. pneumoniae and 27% for H. influenzae 3.

Treatment Failure Protocol

Reassess at 3-5 days (adults) or 72 hours (pediatrics) if no improvement 1, 3, 4. Switch antibiotics if symptoms worsen after 48-72 hours or fail to improve despite 3-5 days of initial therapy 1.

Second-Line Options After Amoxicillin-Clavulanate Failure

Respiratory fluoroquinolones are the preferred second-line choice 3:

• Levofloxacin 500 mg once daily for 10-14 days 3
• Moxifloxacin 400 mg once daily for 10 days 3

These provide excellent coverage against multi-drug resistant S. pneumoniae (MDRSP) and treatment failures 3.

Alternative: High-dose amoxicillin-clavulanate (4 g amoxicillin/250 mg clavulanate per day) for 10-14 days provides enhanced coverage against drug-resistant S. pneumoniae 3.

For pediatric treatment failure: Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses, maximum 2 g every 12 hours) 3.

Adjunctive Therapies

Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily) are strongly recommended as adjuncts to antibiotic therapy, with strong evidence from multiple randomized controlled trials showing they reduce mucosal inflammation and improve symptom resolution 1, 3, 2.

Short-term oral corticosteroids may be reasonable for patients who fail initial treatment, demonstrate nasal polyposis, or have marked mucosal edema, typically for 5 days 3.

Saline nasal irrigation with physiologic or hypertonic saline is recommended for symptomatic relief 1.

Analgesics (acetaminophen, NSAIDs) for pain management 3.

Decongestants and antihistamines are NOT recommended as adjunctive treatment 1.

Special Anatomic Considerations

For maxillary sinusitis (most common type): Use standard first-line antibiotics as outlined above 3.

For frontal, ethmoidal, or sphenoidal sinusitis: Consider fluoroquinolones (levofloxacin or moxifloxacin) due to potential for serious complications, with potentially longer courses of up to 28 days 3, 4.

When to Refer to a Specialist

Refer to otolaryngology, infectious disease, or allergy specialist when 1, 3:

• Symptoms refractory to two courses of appropriate antibiotics
• Recurrent sinusitis (≥3 episodes per year)
• Suspected complications (orbital cellulitis, meningitis, intracranial extension)
• Immunocompromised patients who continue to deteriorate
• Need for sinus aspiration/culture

Critical Pitfalls to Avoid

Do not prescribe antibiotics for viral rhinosinusitis lasting <10 days unless severe symptoms are present - this contributes to antimicrobial resistance without clinical benefit 3.

Do not use mucus color alone to determine antibiotic need, as color reflects neutrophils, not bacteria 3.

Reserve fluoroquinolones appropriately - do not use as routine first-line therapy to prevent resistance development. Use only for treatment failures, complicated sinusitis, multi-drug resistant organisms, or severe beta-lactam allergy 3, 2.

Complete the full antibiotic course even after symptoms improve to prevent relapse 3.

Avoid cefixime and ceftibuten as they have poor activity against penicillin-resistant S. pneumoniae 4.

Never use clindamycin as monotherapy for sinusitis - it lacks activity against H. influenzae and M. catarrhalis, leaving gram-negative pathogens untreated and resulting in treatment failure in 30-40% of cases 3.