What is the recommended treatment for otitis externa?

Treatment of Otitis Externa

Topical antimicrobial preparations are the recommended first-line treatment for uncomplicated otitis externa, while systemic antibiotics should not be prescribed unless there is extension beyond the ear canal or specific host factors requiring systemic therapy. 1

Pathophysiology and Diagnosis

Otitis externa (OE) is a cellulitis of the ear canal skin and subdermis, with acute inflammation and variable edema. Nearly 98% of cases in North America are bacterial, with the most common pathogens being:

• Pseudomonas aeruginosa (20-60%)
• Staphylococcus aureus (10-70%)
• Often occurring as polymicrobial infections 1

Fungal involvement is uncommon in primary OE but may occur in chronic otitis externa or after antibiotic treatment 1.

Treatment Algorithm

1. Initial Assessment

• Determine if the case is uncomplicated (diffuse OE limited to ear canal) or complicated
• Assess for modifying factors:
  • Non-intact tympanic membrane/tympanostomy tubes
  • Diabetes
  • Immunocompromised state
  • Prior radiotherapy 1

2. Pain Management

• Assess pain severity
• For mild to moderate pain: acetaminophen or NSAIDs
• For severe pain: consider opioid-containing analgesics (limited doses for initial 48-72 hours)
• NSAIDs during acute phase significantly reduce pain compared to placebo 1

3. First-Line Treatment for Uncomplicated OE

Topical therapy is the mainstay of treatment:

• Topical antimicrobial preparations with or without steroids
• Advantages: delivers 100-1000 times higher concentration to infected tissue than systemic therapy 1
• Duration: minimum 7 days, with continued use until symptoms resolve (maximum additional 7 days) 1

Choice of Topical Agent:

• Fluoroquinolone preparations (e.g., ofloxacin 0.3% otic solution)

  • Dosage: For patients ≥13 years: 10 drops once daily for 7 days
  • For children 6 months to 13 years: 5 drops once daily for 7 days 2, 3
  • High clinical cure rates: 91% overall (95% in children, 88% in adults) 3
  • High bacterial eradication rates (96%) 3

• Quinolone-containing preparations showed slightly better bacteriologic cure rates compared to non-quinolone preparations 1

4. Special Considerations

For non-intact tympanic membrane:

• Use non-ototoxic preparations (e.g., fluoroquinolones like ofloxacin)
• Avoid aminoglycoside-containing preparations due to potential ototoxicity 1, 4

For fungal otitis externa (otomycosis):

• Suspect if patient fails to respond to initial topical therapy
• Treatment: debridement plus topical antifungal therapy
• Avoid topical antibiotics as they may promote fungal overgrowth 1

5. When to Use Systemic Antibiotics

Systemic antibiotics should only be used when:

• Infection extends beyond the ear canal
• Patient has diabetes or is immunocompromised
• Patient has undergone radiotherapy
• Patient has concurrent acute otitis media requiring systemic treatment 1

6. Aural Toilet (Ear Cleaning)

• Consider when ear canal is obstructed
• Methods: suction, dry mopping, irrigation, removal of obstructing cerumen
• May enhance delivery of topical medications 1

7. Follow-up Assessment

• If no improvement within 48-72 hours, reassess to:
  • Confirm diagnosis
  • Ensure proper medication delivery
  • Consider culture for resistant organisms or fungi
  • Exclude other causes of symptoms 1

Common Pitfalls and Caveats

1. Overuse of systemic antibiotics: Two studies directly showed no significant difference in cure rates between topical therapy alone versus topical plus systemic antibiotics 1

2. Inadequate pain management: Pain from OE can be severe and is often underappreciated by clinicians 1

3. Failure to recognize treatment-resistant cases: Consider fungal infection, contact dermatitis to ear drops, or underlying conditions if no improvement after 7 days 1

4. Inappropriate duration of treatment: Patients should use drops for at least 7 days and continue until symptoms resolve (maximum additional 7 days) 1

5. Using ototoxic preparations with perforated tympanic membrane: Can cause sensorineural hearing loss 1, 4

6. Inadequate patient education on drop administration: Proper technique is essential for effective treatment 1

7. Failure to address underlying causes: Swimming, hearing aids, or ear devices may contribute to recurrence 1

The evidence strongly supports topical therapy as the most effective approach for uncomplicated otitis externa, with systemic antibiotics reserved for specific situations. Fluoroquinolone preparations like ofloxacin show excellent efficacy and safety profiles, particularly when there are concerns about tympanic membrane integrity 3, 4, 5.