What is the recommended treatment for a patient with acute bacterial sinusitis, considering potential allergies and chronic sinusitis?

Treatment for Acute Bacterial Sinusitis

First-Line Antibiotic Treatment

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line treatment for acute bacterial sinusitis in adults. 1, 2

• For children, high-dose amoxicillin-clavulanate (80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses) is recommended, particularly in areas with high prevalence of resistant S. pneumoniae or in children with risk factors (age <2 years, daycare attendance, recent antibiotic use). 1, 2

• High-dose amoxicillin-clavulanate (2 g amoxicillin/125 mg clavulanate twice daily) should be used in adults with recent antibiotic use within the past month, age >65 years, moderate-to-severe symptoms, comorbid conditions, or immunocompromised state. 1, 3

• The clavulanate component provides essential coverage against β-lactamase-producing H. influenzae and M. catarrhalis, which have become increasingly prevalent. 3, 4

Treatment Duration

• Adults: 5-7 days for uncomplicated cases 1, 2
• Children: 10-14 days 1, 2
• Some guidelines recommend treating until symptom-free for 7 days (typically 10-14 days total). 1, 3

Confirming the Diagnosis Before Treatment

Antibiotics should only be prescribed when acute bacterial sinusitis is confirmed by one of three clinical patterns: 1, 2

1. Persistent symptoms: Nasal discharge or daytime cough (or both) for ≥10 days without improvement 1
2. Severe symptoms: Fever ≥39°C (102.2°F) with purulent nasal discharge for ≥3 consecutive days 1
3. "Double sickening": Worsening symptoms after initial improvement from a viral upper respiratory infection 1

Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics. 1, 3

Penicillin-Allergic Patients

For Non-Severe (Non-Type I) Penicillin Allergy

Second- or third-generation cephalosporins are safe and preferred: 1, 3

• Cefuroxime-axetil (second-generation) 1, 3
• Cefpodoxime-proxetil (third-generation, superior activity against H. influenzae) 1, 3
• Cefdinir (third-generation) 1, 3
• Cefprozil (second-generation) 1, 3

The risk of cross-reactivity between penicillins and second/third-generation cephalosporins is negligible (<1%). 3

For Severe (Type I) Penicillin Allergy

Respiratory fluoroquinolones are the treatment of choice: 1, 3

• Levofloxacin 500 mg once daily for 10-14 days 1, 3, 5
• Moxifloxacin 400 mg once daily for 10 days 1, 3

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

Doxycycline 100 mg once daily for 10 days is an acceptable alternative but has a predicted bacteriologic failure rate of 20-25% and limited activity against H. influenzae. 3

What NOT to Use

• Azithromycin and other macrolides should NOT be used due to resistance rates exceeding 20-25% for both S. pneumoniae and H. influenzae. 1, 3, 2, 6
• First-generation cephalosporins (cephalexin, cefadroxil) should NOT be used due to inadequate coverage against H. influenzae. 3
• Trimethoprim-sulfamethoxazole should NOT be used due to 50% resistance rate for S. pneumoniae. 3
• Clindamycin should NEVER be used as monotherapy due to lack of activity against H. influenzae and M. catarrhalis. 3

Treatment Failure Protocol

Reassess at 3-5 days: If no improvement or worsening, switch antibiotics immediately. 1, 3, 2

Second-Line Options After Amoxicillin-Clavulanate Failure

1. Respiratory fluoroquinolones (levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10 days) 1, 3
2. High-dose amoxicillin-clavulanate (2 g/125 mg twice daily) if not already used 1, 3
3. Third-generation cephalosporins (cefpodoxime or cefdinir) 1, 3

Reassess at 7 days: If symptoms persist or worsen, reconfirm diagnosis and exclude complications (orbital cellulitis, meningitis, brain abscess). 1, 3

Essential Adjunctive Therapies

These should be offered to ALL patients regardless of antibiotic choice: 1, 2

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily) reduce mucosal inflammation and improve symptom resolution. 1, 3, 2
• Saline nasal irrigation (physiologic or hypertonic) provides symptomatic relief. 1, 3
• Analgesics (acetaminophen or NSAIDs) for pain and fever. 1, 3

Decongestants and antihistamines are NOT recommended as adjunctive treatment in acute bacterial sinusitis. 1

Watchful Waiting Option

For adults with uncomplicated acute bacterial sinusitis, watchful waiting without immediate antibiotics is appropriate when reliable follow-up can be assured. 3, 2

• Start antibiotics only if no improvement by 7 days or symptoms worsen at any time. 3
• Approximately 73% of bacterial sinusitis cases show spontaneous improvement by 7-12 days without antibiotics. 3

Chronic Sinusitis Considerations

Antibiotics should only be used for acute bacterial exacerbations superimposed on chronic sinusitis, not as routine maintenance therapy. 7

• A minimum 3-week course of antibiotics is recommended for acute exacerbations of chronic sinusitis. 7
• First-line options: amoxicillin-clavulanate (500-875 mg twice daily). 7
• Evaluate for underlying allergic rhinitis, immunodeficiency, and anatomic abnormalities in patients with recurrent sinusitis (≥3 episodes per year). 1, 3, 7

When to Refer to a Specialist

Refer to an otolaryngologist, infectious disease specialist, or allergist when: 1, 3

• No improvement after 7 days of appropriate second-line therapy
• Worsening symptoms at any time despite treatment
• Suspected complications (orbital cellulitis, meningitis, brain abscess)
• Recurrent sinusitis (≥3 episodes per year)
• Immunocompromised patients
• Need for sinus aspiration/culture

Critical Pitfalls to Avoid

• Do NOT prescribe antibiotics for symptoms lasting <10 days unless severe symptoms are present (fever ≥39°C with purulent discharge for ≥3 consecutive days). 1, 2
• Do NOT use fluoroquinolones as routine first-line therapy in patients without documented β-lactam allergies—reserve for treatment failures or severe disease to prevent resistance. 1, 3, 2
• Do NOT continue ineffective therapy beyond 3-5 days—early reassessment is critical to catch treatment failures. 1, 3
• Do NOT use routine MRSA coverage during initial empiric therapy. 1, 2
• Ensure adequate treatment duration (minimum 5 days for adults, 10-14 days for children) to prevent relapse. 1, 2