Otitis Externa
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Basics

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
  • Predominant sex: Male = Female
Prevalence
  • Acute, chronic, and eczematous: Common
  • Necrotizing: Uncommon

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.
  • Diagnose and treat underlying systemic conditions.
  • Use ear plugs when swimming.

Etiology

  • 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 MRSA
    • Associated with immunosuppression

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