What is the best treatment for a patient with bacterial sinusitis?

Treatment of Bacterial Sinusitis

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line treatment for acute bacterial sinusitis in adults, providing superior coverage against β-lactamase-producing organisms that commonly cause treatment failure with amoxicillin alone. 1, 2

Confirming Bacterial Sinusitis Before Starting Antibiotics

Before prescribing antibiotics, confirm the diagnosis using one of three clinical patterns 1:

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

Most acute rhinosinusitis (98-99.5%) is viral and resolves spontaneously within 7-10 days without antibiotics. 1 Do not prescribe antibiotics for symptoms lasting less than 10 days unless severe symptoms are present. 1

First-Line Antibiotic Treatment

Standard Dosing for Most Patients

• Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line choice 1, 2
• Plain amoxicillin 500 mg twice daily (mild disease) or 875 mg twice daily (moderate disease) remains acceptable for uncomplicated cases without recent antibiotic exposure 1

High-Dose Therapy for High-Risk Patients

Use high-dose amoxicillin-clavulanate (2 g amoxicillin/125 mg clavulanate twice daily) for patients with 1:

• Recent antibiotic use within the past month
• Age >65 years
• Moderate-to-severe symptoms
• Comorbid conditions or immunocompromised state
• High local prevalence of drug-resistant Streptococcus pneumoniae

Treatment Duration

• Standard duration is 5-10 days, with most guidelines recommending treatment until symptom-free for 7 days (typically 10-14 days total) 1, 2
• Shorter 5-7 day courses have comparable efficacy with fewer side effects 1

Treatment for Penicillin-Allergic Patients

Non-Severe Penicillin Allergy (Rash, Delayed Reactions)

Second- or third-generation cephalosporins are safe and effective first-line options 1, 3, 2:

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

The risk of serious allergic reactions to second- and third-generation cephalosporins in penicillin-allergic patients is negligible (<1%). 1, 2

Severe Penicillin Allergy (Anaphylaxis, Type I Hypersensitivity)

Respiratory fluoroquinolones are the first-line choice for patients with documented anaphylaxis to penicillin 1, 3:

• Levofloxacin 500 mg once daily for 10-14 days 1, 3, 4
• 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. 1, 4

Alternative option: Doxycycline 100 mg once daily for 10 days is acceptable but has a 20-25% predicted bacteriologic failure rate and limited activity against H. influenzae. 1, 3

Second-Line Treatment for Treatment Failure

If no improvement occurs after 3-5 days of initial therapy, switch antibiotics. 1, 2

After Amoxicillin Failure

• Switch to high-dose amoxicillin-clavulanate (875 mg/125 mg twice daily or 2 g/125 mg twice daily) 1, 2

After Amoxicillin-Clavulanate Failure

• Switch to a respiratory fluoroquinolone (levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10-14 days) 1
• Alternative: Third-generation cephalosporins (cefpodoxime or cefdinir) offer superior activity against H. influenzae 1

For Patients Unable to Tolerate Oral Medications

• Ceftriaxone 1-2 g IM or IV once daily for 5 days provides 90-92% predicted clinical efficacy 1
• Pediatric dose: 50 mg/kg IM or IV once daily 1

Antibiotics to AVOID

Never use these antibiotics as first-line therapy for bacterial sinusitis 1:

• Azithromycin and other macrolides - resistance rates exceed 20-25% for both S. pneumoniae and H. influenzae 1, 5, 6
• Trimethoprim-sulfamethoxazole - 50% resistance rate for S. pneumoniae and 27% for H. influenzae 1
• First-generation cephalosporins (cephalexin, cefadroxil) - inadequate coverage against H. influenzae (nearly 50% of strains are β-lactamase producing) 1
• Clindamycin as monotherapy - lacks activity against H. influenzae and M. catarrhalis, leading to 30-40% failure rate 1

Adjunctive Therapies to Enhance Outcomes

Intranasal Corticosteroids (Strongly Recommended)

• Mometasone, fluticasone, or budesonide twice daily reduce mucosal inflammation and improve symptom resolution 1, 2
• These should be added to antibiotic therapy in both acute and chronic sinusitis 1, 2

Short-Term Oral Corticosteroids (Selective Use)

• Consider for patients with marked mucosal edema or who fail to respond to initial antibiotic treatment 1
• Typical duration is 5 days 1
• Never give systemic corticosteroids without antibiotics when bacterial sinusitis is suspected, as this may suppress immune response and allow bacterial proliferation 1

Supportive Measures

• Adequate hydration 1
• Analgesics (acetaminophen or NSAIDs) for pain and fever 1
• Saline nasal irrigation for symptomatic relief and mucus removal 1, 2
• Warm facial packs 1
• Sleeping with head elevated 1
• Short-term decongestants (pseudoephedrine) - avoid prolonged use due to rebound congestion 1, 2

Monitoring and Follow-Up

• Reassess at 3-5 days: If no improvement, switch antibiotics or re-evaluate diagnosis 1, 2
• Reassess at 7 days: Confirm diagnosis if symptoms persist or worsen 1
• Most patients should experience noticeable improvement within 3-5 days of starting appropriate antibiotic therapy 1
• Approximately 90% of patients improve naturally within 7-15 days, even without antibiotics 1

When to Refer to a Specialist

Refer to otolaryngology or allergy-immunology for 1, 2:

• Symptoms refractory to two courses of appropriate antibiotics
• Recurrent sinusitis (≥3 episodes per year)
• Suspected complications (orbital cellulitis, meningitis, brain abscess)
• Need for sinus aspiration/culture in immunocompromised patients
• Evaluation for underlying allergic rhinitis, immunodeficiency, or anatomical abnormalities

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 1
• Do not use fluoroquinolones as routine first-line therapy in patients without documented β-lactam allergies - reserve them for treatment failures or severe allergies to prevent resistance development 1, 3
• Do not continue ineffective therapy beyond 3-5 days without reassessment 1, 2
• Do not use mucus color alone to determine antibiotic need - color reflects neutrophils, not bacteria 1
• Complete the full course of antibiotics even after symptoms improve to prevent relapse 1, 2

Watchful Waiting as an Alternative Strategy

For adults with uncomplicated acute bacterial sinusitis, watchful waiting without immediate antibiotics is an appropriate initial strategy when reliable follow-up can be assured. 1, 3 Instruct patients to start antibiotics only if no improvement occurs by 7 days or if symptoms worsen at any time. 1 The number needed to treat with antibiotics is 10-15 to get one additional person better after 7-15 days. 1