What are the criteria for prescribing antibiotics in patients with acute sinusitis?

Criteria for Prescribing Antibiotics in Acute Sinusitis

Antibiotics should be prescribed only when acute bacterial sinusitis is confirmed by one of three specific clinical patterns: persistent symptoms ≥10 days without improvement, severe symptoms (fever ≥39°C with purulent nasal discharge) for ≥3-4 consecutive days, or "double sickening" (worsening after initial improvement from a viral upper respiratory infection). 1, 2, 3

Diagnostic Criteria: The Three Patterns

You must identify at least one of these patterns before prescribing antibiotics:

Pattern 1: Persistent Symptoms (Most Common)

• Nasal congestion, purulent nasal discharge, or facial pain/pressure lasting ≥10 days without any clinical improvement 1, 2, 3
• This is the most reliable indicator, as symptoms lasting <10 days are almost always viral 4, 1

Pattern 2: Severe Symptoms

• High fever ≥39°C (102°F) with purulent nasal discharge for ≥3-4 consecutive days at the onset of illness 1, 2, 5
• Unilateral facial pain or pressure that worsens when bending forward 1

Pattern 3: "Double Sickening"

• Initial improvement from a viral upper respiratory infection, followed by worsening of respiratory symptoms (with or without fever) 1, 2, 5
• This pattern suggests bacterial superinfection 1

Clinical Features That Increase Likelihood of Bacterial Infection

While not diagnostic alone, these combinations strengthen the diagnosis:

• Persistent purulent nasal discharge (≥7 days) with maxillary tooth pain or unilateral facial pain 4
• Unilateral sinus tenderness on examination 4
• Symptoms worsening after initial improvement 4

Critical Pitfall: Most Cases Are Viral

98-99.5% of acute rhinosinusitis is viral and resolves spontaneously within 7-10 days without antibiotics. 1, 3 Do not prescribe antibiotics for:

• Symptoms lasting <10 days unless severe symptoms are present 1, 2, 3
• Mucus color alone (purulent discharge reflects neutrophils, not bacteria) 1
• Radiographic findings alone (abnormal imaging is common in viral sinusitis) 4

When Imaging Is NOT Recommended

• Sinus radiography and CT are not recommended for uncomplicated acute rhinosinusitis due to high prevalence of abnormal findings in viral cases 4, 1
• Reserve imaging only for suspected complications (orbital cellulitis, meningitis, brain abscess) or when alternative diagnosis is likely 1, 3

Watchful Waiting as Initial Strategy

For patients with mild-to-moderate symptoms meeting bacterial criteria, watchful waiting without immediate antibiotics is appropriate when reliable follow-up can be assured. 1, 2 Instruct patients to:

• Start antibiotics only if no improvement by 7 days or worsening at any time 1, 2
• Use symptomatic treatment (analgesics, intranasal corticosteroids, saline irrigation) during observation period 4, 1, 2

First-Line Antibiotic Selection (When Indicated)

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-7 days is the preferred first-line agent for adults. 1, 2, 3 This provides coverage against β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis, which have become increasingly prevalent 1, 2

Alternative for Mild Disease Without Recent Antibiotic Use:

• Plain amoxicillin 500 mg twice daily (mild) or 875 mg twice daily (moderate) for 5-7 days 1, 2

For Penicillin-Allergic Patients (Non-Severe Allergy):

• Second-generation cephalosporins: cefuroxime-axetil 1, 2
• Third-generation cephalosporins: cefpodoxime-proxetil or cefdinir 1, 2, 3

For Severe Penicillin Allergy:

• Respiratory fluoroquinolones: levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10 days 1, 2, 6, 7
• Doxycycline 100 mg once daily for 10 days (acceptable but suboptimal, with 20-25% predicted failure rate) 1, 3

What NOT to Use

• Azithromycin and macrolides: Resistance rates exceed 20-25% for both S. pneumoniae and H. influenzae 1, 2
• First-generation cephalosporins (cephalexin): Inadequate coverage against H. influenzae 1
• Trimethoprim-sulfamethoxazole: 50% resistance rate for S. pneumoniae 1

Reassessment Timeline

• 3-5 days: If no improvement, switch to second-line therapy (high-dose amoxicillin-clavulanate or respiratory fluoroquinolone) 1, 2
• 7 days: If symptoms persist or worsen, reconfirm diagnosis and consider complications or alternative diagnosis 1, 2

Adjunctive Therapies (Recommended for All Patients)

• Intranasal corticosteroids (mometasone, fluticasone, budesonide twice daily): Reduce mucosal inflammation and improve symptom resolution 1, 2, 3
• Saline nasal irrigation: Provides symptomatic relief 1, 2, 3
• Analgesics (acetaminophen, NSAIDs): Relieve pain and fever 1, 2