How is a sinus infection diagnosed and treated?

Diagnosis and Treatment of Sinus Infection

When to Diagnose Acute Bacterial Sinusitis

Suspect acute bacterial sinusitis when upper respiratory symptoms persist beyond 10-14 days without improvement, or when severe symptoms (high fever with purulent nasal discharge) are present for 3-4 consecutive days. 1

Three Clinical Presentations Warrant Diagnosis:

• Persistent symptoms: Nasal congestion, discharge, or cough lasting >10 days but <30 days without improvement 2
• Severe onset: High fever (≥39°C) with purulent nasal discharge for 3-4 consecutive days 2
• Worsening symptoms: Initial improvement from viral URI followed by clinical deterioration 2

Key Diagnostic Symptoms in Adults:

• Purulent rhinorrhea (most predictive) 1
• Facial or dental pain (most predictive) 1
• Nasal congestion 1
• Postnasal drainage 1
• Headache 1
• Cough (often worse at night) 1

Key Diagnostic Symptoms in Children:

• Persistent cough (>10 days) 1
• Purulent nasal discharge 1
• Increased irritability 1
• Vomiting associated with gagging on mucus 1

How to Diagnose

Physical Examination Findings:

The diagnosis is primarily clinical, based on history and physical examination. 1

• Sinus tenderness on palpation 1
• Mucosal erythema with purulent nasal secretions 1
• Purulent material in posterior pharynx 1
• Periorbital edema 1
• Pharyngeal erythema and lymphoid hyperplasia 1

When Imaging is NOT Needed:

Plain radiographs are generally not necessary for diagnosing acute sinusitis and have significant false-positive and false-negative results. 1

When Imaging IS Indicated:

CT scanning should be reserved for specific situations, not routine diagnosis: 1

• Symptoms are vague or physical findings equivocal 1
• Clinical disease persists despite optimal medical therapy 1
• Consideration for surgical intervention 1
• Suspected complications (orbital involvement, intracranial extension) 1

Red Flags Requiring Urgent Evaluation:

Any patient with the following requires immediate assessment: 1

• Orbital swelling, pain, or diplopia 1
• Proptosis or abnormal extraocular movements 1
• Periorbital inflammation, edema, or erythema 1
• Facial swelling or erythema over involved sinus 1
• Visual changes 1
• Altered mental status or neurologic signs suggesting intracranial involvement 1

Treatment Approach

First-Line Antibiotic Therapy:

Start amoxicillin as first-line treatment for 10-14 days (or until symptom-free for 7 days). 1

• Amoxicillin is effective, inexpensive, and well-tolerated for both children and adults 1
• Assess response at 3-5 days 1
• If improving, continue until well for 7 days (typically 10-14 day total course) 1

Second-Line Options if No Improvement at 3-5 Days:

Switch to high-dose amoxicillin-clavulanate or cefuroxime axetil if no improvement after 3-5 days. 1

• High-dose amoxicillin-clavulanate (90 mg/kg amoxicillin and 6.4 mg/kg clavulanate, not exceeding 2g every 12 hours) 1
• Alternative: cefuroxime axetil 1
• For penicillin allergy: cephalosporins, macrolides, or quinolones 1
• Trimethoprim-sulfamethoxazole as alternative in adults (though resistance more common in children) 1

For Recurrent Sinusitis (≥3 Episodes/Year):

High-dose amoxicillin-clavulanate (1.5-4g/day) for 10-14 days is first-line for recurrent infections. 3

• Consider broader-spectrum coverage or anaerobic coverage with clindamycin/metronidazole if no improvement 3
• Evaluate underlying causes including allergic rhinitis, immunodeficiency, anatomic obstruction 3

Adjunctive Therapies:

Intranasal corticosteroids are helpful as adjunct therapy, particularly in chronic or recurrent cases. 1, 3

• Nasal corticosteroids reduce inflammation and improve drainage 3
• Short-term oral corticosteroids reasonable when patient fails initial treatment, has nasal polyposis, or marked mucosal edema 1
• Saline nasal irrigation helps clear secretions 3
• Adequate hydration, analgesics, warm facial compresses, sleeping with head elevated 1, 3

Chronic Sinusitis (>8 Weeks):

Chronic sinusitis requires longer antibiotic courses with attention to anaerobic pathogens and consideration of non-infectious causes. 1

• For chronic infectious sinusitis: longer duration therapy targeting anaerobes 1
• For chronic hyperplastic eosinophilic sinusitis: systemic corticosteroids rather than prolonged antibiotics 1
• CT imaging should document persistent inflammation at least 4 weeks after appropriate medical therapy 1

Common Pitfalls to Avoid:

• Overdiagnosis: Only use antibiotics when symptoms persist ≥10-14 days or severe symptoms are present 1
• Incomplete treatment: Patients must complete full 10-14 day course even if improving 1, 3
• Premature imaging: Plain films are unreliable; reserve CT for treatment failures or surgical planning 1
• Missing complications: Always examine for orbital or neurologic involvement 1
• Ignoring underlying conditions: Evaluate for allergic rhinitis, immunodeficiency, or anatomic obstruction in recurrent cases 1, 3