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

Antibiotic Treatment for Acute Bacterial Sinusitis

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-7 days is the preferred first-line antibiotic for adults with acute bacterial sinusitis, due to the high prevalence (20-30%) of β-lactamase-producing organisms that render plain amoxicillin ineffective. 1

Confirming the Diagnosis Before Prescribing

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

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

Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics 2. Do not prescribe antibiotics for symptoms lasting <10 days unless severe symptoms are present 2, 3.

First-Line Treatment Algorithm

For Adults Without Penicillin Allergy

Standard therapy: Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-7 days 1, 3

High-dose therapy (use if recent antibiotic exposure within past month, age >65 years, comorbid conditions, or immunocompromised): Amoxicillin-clavulanate 2000 mg/125 mg twice daily 2, 3

The clavulanate component provides essential coverage against β-lactamase-producing Haemophilus influenzae (20-30% of cases) and Moraxella catarrhalis (12-28% of cases) 1. Plain amoxicillin is no longer appropriate as first-line therapy 1, 3.

For Pediatric Patients

Standard therapy: Amoxicillin 45 mg/kg/day in 2 divided doses for 10-14 days 2, 3

High-dose therapy (for age <2 years, daycare attendance, recent antibiotic use, or high local resistance): Amoxicillin-clavulanate 80-90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses 2, 1, 3

Penicillin-Allergic Patients

Non-Severe Allergy (Rash, Delayed Reactions)

Second- or third-generation cephalosporins are safe and effective, as the risk of serious cross-reactivity is negligible 2, 1, 3:

• Cefuroxime-axetil (second-generation): 250-500 mg twice daily 5, 2
• Cefpodoxime-proxetil (third-generation): 200-400 mg twice daily 5, 2
• Cefdinir (third-generation): 300 mg twice daily 2, 1

Third-generation cephalosporins provide superior activity against H. influenzae compared to second-generation agents 2.

Severe Type I Hypersensitivity (Anaphylaxis)

Respiratory fluoroquinolones are the treatment of choice 2, 1, 3:

• Levofloxacin 500 mg once daily for 10-14 days 2, 1, 6
• Moxifloxacin 400 mg once daily for 10 days 2, 1

Fluoroquinolones demonstrate 90-92% predicted clinical efficacy and 100% microbiologic eradication of S. pneumoniae, including multi-drug resistant strains 2, 6, 7.

Treatment Failure Protocol

Reassess at 3-5 days (adults) or 72 hours (pediatrics) 2, 1, 3. If no improvement or worsening symptoms:

1. Switch to high-dose amoxicillin-clavulanate (if not already prescribed): 2000 mg/125 mg twice daily for adults 2, 3

2. If amoxicillin-clavulanate fails, switch to a respiratory fluoroquinolone 2, 1, 3:

   • Levofloxacin 500-750 mg once daily for 10-14 days 2, 6
   • Moxifloxacin 400 mg once daily for 10 days 2, 1

3. Consider ceftriaxone for patients unable to tolerate oral medications: 1-2 g IM/IV once daily for 5 days (adults) or 50 mg/kg once daily (pediatrics) 2

Antibiotics to AVOID

Never use these agents as first-line therapy for acute bacterial sinusitis:

• Azithromycin and macrolides: Resistance rates exceed 20-25% for both S. pneumoniae and H. influenzae 2, 1, 8, 4
• First-generation cephalosporins (cephalexin): Inadequate coverage against H. influenzae 2
• Clindamycin monotherapy: No activity against H. influenzae or M. catarrhalis 2
• Trimethoprim-sulfamethoxazole: Resistance rates of 50% for S. pneumoniae and 27% for H. influenzae 2

Adjunctive Therapies That Improve Outcomes

Intranasal corticosteroids should be added to antibiotic therapy in all patients 2, 1, 3:

• Mometasone, fluticasone, or budesonide twice daily 2, 3
• Reduces mucosal inflammation and improves symptom resolution 2, 1

Short-term oral corticosteroids (5 days) may be considered for 2:

• Patients who fail initial antibiotic treatment 2
• Marked mucosal edema 2
• Severe pain (acute hyperalgic sinusitis) 2

Supportive measures 2, 1:

• Intranasal saline irrigation 2
• Analgesics (acetaminophen, NSAIDs) 2
• Adequate hydration 2
• Warm facial packs 2

Treatment Duration

Adults: 5-7 days for uncomplicated maxillary sinusitis 1, 3. Shorter courses (5-7 days) have comparable efficacy with fewer side effects compared to 10-14 day courses 2, 1, 9.

Pediatrics: 10-14 days or until symptom-free for 7 days 2, 1, 3

Frontal, ethmoidal, or sphenoidal sinusitis: Consider longer duration (10-14 days) due to higher risk of complications 5, 2

When to Refer to a Specialist

Refer to otolaryngology or allergy/immunology for 2:

• Symptoms refractory to two courses of appropriate antibiotics 2
• Recurrent sinusitis (≥3 episodes per year) 2
• Suspected complications: orbital cellulitis, meningitis, severe frontal/sphenoidal sinusitis 5, 2
• Need for sinus aspiration/culture in immunocompromised patients 2

Critical Pitfalls to Avoid

• Do not prescribe antibiotics for viral rhinosinusitis lasting <10 days unless severe symptoms are present 2, 3
• Do not use plain amoxicillin as first-line therapy given high prevalence of β-lactamase-producing organisms 1, 3
• Do not continue ineffective antibiotics beyond 3-5 days—failure to reassess and switch therapy leads to prolonged illness and complications 2, 1, 3
• Do not reserve fluoroquinolones as routine first-line therapy—use only for treatment failures, severe disease, or documented penicillin allergy to prevent resistance 2, 1, 6
• Do not use systemic corticosteroids without antibiotics when bacterial sinusitis is suspected, as this may suppress immune response and allow bacterial proliferation 2