What is the recommended antibiotic treatment for a patient with acute bacterial sinusitis?

Antibiotic Treatment for Acute Bacterial Sinusitis

For adults with acute bacterial sinusitis, prescribe amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-7 days as first-line therapy, or consider watchful waiting for 7 days in patients with reliable follow-up. 1, 2

Confirm the Diagnosis First

Before prescribing antibiotics, verify the patient meets one of three diagnostic criteria for bacterial (not viral) sinusitis: 1, 2, 3

• Persistent symptoms ≥10 days without clinical improvement (nasal congestion, purulent discharge, facial pain/pressure) 1, 2
• Severe symptoms for ≥3-4 consecutive days: fever ≥39°C with purulent nasal discharge 1, 2, 3
• "Double sickening": worsening symptoms after initial improvement from a viral upper respiratory infection 1, 2, 3

Critical caveat: 98-99.5% of acute rhinosinusitis is viral and resolves spontaneously within 7-10 days without antibiotics. 2, 4 Do not prescribe antibiotics for symptoms lasting less than 10 days unless severe symptoms are present. 1, 2

First-Line Treatment Options

Standard Approach: Amoxicillin-Clavulanate

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-7 days is the preferred first-line antibiotic for most adults. 1, 2, 3, 4 This provides 90-92% predicted clinical efficacy against the three major pathogens: Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. 2, 4 The clavulanate component covers β-lactamase-producing organisms, which account for nearly 50% of H. influenzae and 90-100% of M. catarrhalis strains. 2

Shorter courses (5-7 days) have comparable efficacy to traditional 10-day regimens with fewer adverse effects. 1, 5 However, treatment should continue until symptom-free for 7 days, which typically results in a 10-14 day total course. 1, 2

Alternative: Watchful Waiting

Watchful waiting without immediate antibiotics is appropriate when reliable follow-up can be assured. 1, 4 Give the patient a prescription but instruct them to fill it only if symptoms fail to improve by 7 days or worsen at any time. 1 This approach reduces antibiotic exposure, adverse events, and resistance development. 1

High-Dose Amoxicillin-Clavulanate

Use high-dose amoxicillin-clavulanate (2 g amoxicillin/125 mg clavulanate twice daily) for patients with: 2, 4

• Recent antibiotic use within the past month 2, 4
• Age >65 years 2, 4
• Moderate-to-severe symptoms 2, 4
• Comorbid conditions or immunocompromised state 2, 4

Important note: Recent research shows conflicting results on high-dose efficacy. One study found 18% greater improvement at day 3 with high-dose immediate-release formulation, 6 but a subsequent larger trial found no benefit and stopped early for futility. 7 The extended-release formulation showed no advantage. 6

Penicillin-Allergic Patients

Non-Severe Allergy (Rash, Delayed Reaction)

For non-Type I hypersensitivity, use second- or third-generation cephalosporins: 1, 2, 4

• Cefuroxime-axetil (second-generation) 1, 2, 4
• Cefpodoxime-proxetil (third-generation, superior activity against H. influenzae) 1, 2, 4
• Cefdinir (third-generation) 1, 2, 4

The risk of cross-reactivity between penicillins and second/third-generation cephalosporins is negligible. 2

Severe Allergy (Anaphylaxis, Type I Hypersensitivity)

For documented severe penicillin allergy, use respiratory fluoroquinolones: 2, 4

• Levofloxacin 500 mg once daily for 10-14 days 2, 4
• Moxifloxacin 400 mg once daily for 10 days 2, 4

These provide 90-92% predicted clinical efficacy with excellent coverage against drug-resistant S. pneumoniae and β-lactamase-producing organisms. 2, 4

Do NOT use: 2

• Azithromycin or other macrolides: 20-25% resistance rates for both S. pneumoniae and H. influenzae 2
• Trimethoprim-sulfamethoxazole: 50% resistance for S. pneumoniae, 27% for H. influenzae 2
• Doxycycline: 20-25% predicted bacteriologic failure rate, limited activity against H. influenzae 2

Treatment Failure Protocol

Reassess at 3-5 days: If no improvement or worsening symptoms, switch antibiotics immediately. 1, 2, 3, 4

Reassess at 7 days: If symptoms persist, reconfirm the diagnosis, exclude complications (orbital cellulitis, meningitis, brain abscess), and switch to second-line therapy. 1, 2

Second-Line Options After Amoxicillin-Clavulanate Failure

• Respiratory fluoroquinolones (levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10 days) 2, 4
• High-dose amoxicillin-clavulanate (if not already used) 2, 4
• Ceftriaxone 1-2 g IM/IV once daily for 5 days (for patients unable to tolerate oral medications or with moderate-to-severe disease) 2

Adjunctive Therapies (Essential for All Patients)

Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily) reduce mucosal inflammation and improve symptom resolution. 1, 2, 4 These should be added to antibiotic therapy in all patients. 2, 4

Supportive measures: 1, 2

• Saline nasal irrigation for symptomatic relief 1, 2
• Analgesics (acetaminophen or ibuprofen) for pain and fever 1, 2
• Adequate hydration 2

Short-term oral corticosteroids (e.g., dexamethasone 4 mg for 5 days) may be considered for patients with marked mucosal edema or acute hyperalgic sinusitis (severe pain) who fail to respond to initial treatment. 2

Pediatric Dosing

Standard-dose amoxicillin: 45 mg/kg/day in 2 divided doses for 10-14 days (mild disease without recent antibiotic use) 2, 3

High-dose amoxicillin: 80-90 mg/kg/day in 2 divided doses for children with risk factors (age <2 years, daycare attendance, recent antibiotic use, or high local resistance rates) 2, 3

High-dose amoxicillin-clavulanate: 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses for treatment failures or children with risk factors 2, 3, 4

Reassess pediatric patients at 72 hours and switch to second-line therapy if no improvement. 2

Critical Pitfalls to Avoid

• Do not use first-generation cephalosporins (cephalexin, cefadroxil) due to inadequate coverage against H. influenzae. 2
• Reserve fluoroquinolones for treatment failures or documented severe β-lactam allergies to prevent resistance development. 1, 2, 4
• Do not prescribe antibiotics for viral rhinosinusitis lasting <10 days unless severe symptoms are present. 1, 2, 4
• Ensure adequate treatment duration (minimum 5-7 days for adults, 10-14 days for children) to prevent relapse. 1, 2, 5
• Gastrointestinal adverse effects are common with amoxicillin-clavulanate (diarrhea in 40-43% of patients, severe diarrhea in 7-8%). 2

When to Refer to a Specialist

Refer to otolaryngology or allergist-immunologist for: 2

• Symptoms refractory to two courses of appropriate antibiotics 2
• Recurrent sinusitis (≥3 episodes per year) 2
• Suspected complications (orbital cellulitis, meningitis, brain abscess) 2
• Need for evaluation of underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities 2