What is the treatment for otitis externa in adults?

Treatment of Otitis Externa in Adults

The first-line treatment for otitis externa in adults is topical antibiotic therapy, specifically fluoroquinolone drops or azole antifungals (for fungal causes), combined with thorough cleansing of the ear canal. 1, 2

Diagnosis and Etiology

• Otitis externa is an infection of the external auditory canal with variable involvement of the pinna
• Most common causative organisms:
  • Bacterial: Pseudomonas aeruginosa and Staphylococcus aureus 3
  • Fungal: Aspergillus or Candida species (otomycosis) 3, 1
• Clinical presentation includes otalgia, tenderness, fever, and ear discharge
• Diagnosis is primarily clinical, with tenderness on movement of the tragus or pinna being a classic finding 2

Treatment Algorithm

Step 1: Ear Canal Preparation

• Thoroughly cleanse and dry the external auditory canal with a sterile cotton applicator 4
• Perform aural toilet to remove inflammatory debris and obstructing cerumen using gentle suctioning or dry mop technique 1

Step 2: Medication Selection

For Bacterial Otitis Externa:

• First-line: Topical fluoroquinolone drops (e.g., ofloxacin 0.3%)

  • Advantages: Once-daily dosing possible, no risk of ototoxicity, effective against common pathogens 5, 2
  • Application: 4-5 drops in affected ear once daily for 7-10 days 5

• Alternative: Neomycin/polymyxin B/hydrocortisone preparations

  • Application: 4 drops 3-4 times daily for up to 10 days 4
  • Caution: Increasing resistance patterns have been observed 6 and risk of contact dermatitis with neomycin

For Fungal Otitis Externa (Otomycosis):

• First-line: Clotrimazole 1% or miconazole solution for 7-14 days 1
• Alternative: Boric acid or acetic acid solutions 1
• For refractory cases: Voriconazole 1% solution (3 drops, 3-4 times daily for 14 days) 1

Step 3: Proper Administration Technique

• Patient should lie with affected ear upward
• Instill prescribed drops into the ear canal
• Maintain position for 5 minutes to facilitate penetration 4
• Use gentle tragal pumping to aid medication delivery 1
• Alternative: Insert cotton wick into canal, saturate with solution, replace every 24 hours 4

Step 4: Adjunctive Measures

• Pain control with analgesics as needed
• Keep ear dry during treatment
• Avoid swimming and submerging head in water
• Avoid inserting objects into ear canal

Special Considerations

Necrotizing (Malignant) Otitis Externa

• Watch for in immunocompromised patients or poorly controlled diabetics 3
• Requires systemic antibiotics and close monitoring 1
• High morbidity and mortality if not treated appropriately 3

When to Consider Oral Antibiotics

• Extension of infection beyond the ear canal
• Patients at risk for rapidly progressing infection
• Immunocompromised patients 2

Common Pitfalls to Avoid

1. Inappropriate antibiotic selection: Many oral antibiotics prescribed are not active against S. aureus or P. aeruginosa 7
2. Overuse of systemic antibiotics: Appropriate topical treatment is usually sufficient; systemic medications increase costs and side effects 7
3. Insufficient ear cleaning: Failure to adequately clean the ear canal before medication application reduces treatment efficacy 1
4. Using ototoxic preparations with perforated tympanic membrane: Always assess tympanic membrane integrity before selecting ear medications 1
5. Insufficient treatment duration: Premature discontinuation can lead to recurrence 1
6. Prolonged use of topical antibiotics: Can promote fungal overgrowth 1

Prevention of Recurrence

• Keep ears dry
• Avoid cleaning ear canal with cotton swabs
• Treat predisposing factors (dermatitis, immunosuppression, diabetes)
• Consider acidifying ear drops after swimming for those prone to recurrent infections 1