Description

Inflammation of the external auditory canal:

• Acute diffuse otitis externa: the most common form; an infectious process; usually bacterial; occasionally fungal (10%)
• Acute circumscribed otitis externa: synonymous with furuncle; associated with infection of the hair follicle, a superficial cellulitic form of otitis externa
• Chronic otitis externa: same as acute diffuse but of longer duration (>6 weeks)
• Eczematous otitis externa: may accompany typical atopic eczema or other primary skin conditions
• Necrotizing malignant otitis externa: an infection that extends into the deeper tissues adjacent to the canal; may include osteomyelitis and cellulitis; rare in children
• System(s) affected: skin/exocrine
• Synonym(s): swimmer’s ear

Epidemiology

Incidence

• Unknown; higher in the summer months and in warm, wet climates
• Predominant age: all ages

Prevalence

• Acute, chronic, and eczematous: common
• Necrotizing: uncommon

Etiology and Pathophysiology

• Acute diffuse otitis externa
  • Traumatized external canal (e.g., from use of cotton swab)
  • Bacterial infection (90%): Pseudomonas (67%), Staphylococcus, Streptococcus, gram-negative rods
  • Fungal infection (10%): Aspergillus (90%), Candida, Phycomycetes, Rhizopus, Actinomyces, Penicillium
• Chronic otitis externa: bacterial infection: Pseudomonas
• Eczematous otitis externa (associated with primary skin disorder)
  • Eczema, seborrhea, psoriasis
  • Neurodermatitis
  • Contact dermatitis
  • Purulent otitis media
  • Sensitivity to topical medications
• Necrotizing otitis externa
  • Invasive bacterial infection: Pseudomonas, increasing incidence of methicillin-resistant Staphylococcus aureus (MRSA)
  • Associated with immunosuppression

Risk Factors

• Acute and chronic otitis externa
  • Traumatization of external canal
  • Swimming
  • Hot, humid weather
  • Hearing aid use
• Eczematous: primary skin disorder
• Necrotizing otitis externa in adults
  • Advanced age
  • Diabetes mellitus (DM)
  • Debilitating disease
  • AIDS, immunosuppression
• Necrotizing otitis externa in children (rare)
  • Leukopenia
  • Malnutrition
  • DM
  • Diabetes insipidus

General Prevention

• Avoid prolonged exposure to moisture.
• Use preventive antiseptics (acidifying solutions with 2% acetic acid [white vinegar] diluted 50/50 with water or isopropyl alcohol or 2% acetic acid with aluminum acetate [less irritating]) after swimming and bathing.
• Treat predisposing skin conditions.
• Eliminate self-inflicted trauma to canal with cotton swabs and other foreign objects.
• Treat underlying systemic conditions.
• Ear plugs when swimming