What antibiotics are used to treat otitis externa?

Antibiotics for Otitis Externa

Topical fluoroquinolone eardrops (such as ciprofloxacin 0.2% or ofloxacin 0.3%) should be used as first-line treatment for uncomplicated otitis externa, administered twice daily for 7 days. 1

First-Line Treatment Options

Topical therapy is strongly recommended for initial treatment of diffuse, uncomplicated otitis externa for several reasons:

• Provides higher drug concentration at the infection site
• Better coverage of likely pathogens (especially Pseudomonas aeruginosa)
• Fewer systemic adverse effects
• Lower risk of antibiotic resistance 1

Preferred Topical Antibiotics:

1. Fluoroquinolone preparations:

   • Ciprofloxacin 0.2% - twice daily for 7 days
   • Ofloxacin 0.3% - once daily for 7 days 1, 2

2. Alternative options (if tympanic membrane is intact):

   • Acetic acid preparations
   • Aminoglycoside-containing preparations 1

Important note: Recent studies show declining susceptibility to neomycin and polymyxin B among pathogens causing otitis externa, while susceptibility to fluoroquinolones remains stable 3

Dosing Guidelines

• For children (6 months to 13 years): Five drops (0.25 mL) of ofloxacin 0.3% instilled into the affected ear once daily for seven days 2
• For patients 13 years and older: Ten drops (0.5 mL) of ofloxacin 0.3% instilled into the affected ear once daily for seven days 2

Administration Technique

1. Warm the solution by holding the bottle in hand for 1-2 minutes (prevents dizziness)
2. Position patient with affected ear upward
3. Instill the drops
4. Maintain position for 5 minutes to facilitate penetration 2

When Systemic Antibiotics Are Indicated

The American Academy of Otolaryngology-Head and Neck Surgery strongly recommends against systemic antibiotics as initial therapy for uncomplicated otitis externa 4, 1.

Systemic antibiotics should be reserved for specific scenarios:

• Extension of infection outside the ear canal
• Presence of specific host factors:
  • Diabetes mellitus
  • Immunocompromised state
  • History of radiotherapy
  • Necrotizing (malignant) otitis externa
  • Concurrent acute otitis media
  • Cellulitis of the pinna or adjacent skin 4, 1

Selection of Oral Antibiotics (When Indicated)

When systemic antibiotics are necessary:

• First choice: Fluoroquinolones (ciprofloxacin) - provides coverage for Pseudomonas aeruginosa 1

Special Considerations

Non-intact Tympanic Membrane

• Use non-ototoxic topical preparations (such as fluoroquinolones)
• Avoid aminoglycosides due to potential ototoxicity 4, 1

Treatment Failure

• If no response within 48-72 hours, reassess to:
  • Confirm diagnosis
  • Exclude other causes
  • Consider alternative therapy 4

Prevention of Recurrence

• Keep ears dry
• Use ear protection when showering or washing hair
• Avoid ear canal cleaning with cotton-tip applicators 1

Efficacy Comparison

Studies show that fluoroquinolone preparations (like ofloxacin) are as effective as neomycin/polymyxin B/hydrocortisone combinations, with comparable clinical cure rates (93.8% vs 94.7%) 5. However, fluoroquinolones have the advantage of:

• No risk of ototoxicity (unlike neomycin)
• Maintained susceptibility patterns (unlike declining susceptibility to neomycin/polymyxin B) 3
• Effective pain relief without adjunctive steroids 5