Inflammation of the external auditory canal:
- Acute diffuse otitis externa (AOE) (<6 weeks): most common form; infectious etiology most commonly bacterial (Pseudomonas aeruginosa and Staphylococcus aureus); less commonly fungal (Aspergillus and Candida)
- Chronic otitis externa (>3 months): commonly due to inadequately treated acute otitis externa, persistent allergies, or chronic skin conditions
- Eczematous otitis externa: may accompany typical atopic eczema or other primary skin conditions
- Malignant (necrotizing) otitis externa: an infection that extends into the deeper tissues adjacent to the canal; may include osteomyelitis of the mastoid or temporal bone; a medical emergency requiring urgent referral; can be life-threatening; rare, especially in children (1)
- Synonym(s): swimmer’s ear
- Annual incidence of ~1% (2)
- Higher in the summer months and in warm, wet climates
- Can affect all age groups but has a peak incidence in 7- to 12-year-olds (3)
Lifetime prevalence of 10% (2)
Etiology and Pathophysiology
- Factors associated with pathogenesis:
- Skin, cerumen, and surrounding structures provide protection for the integrity of external auditory canal.
- Cerumen, being a hydrophobic and sticky substance, provides a physical barrier against many foreign particles. Normal cerumen production also creates an environment that is slightly acidic and not favorable for most pathogens.
- Disruption of the protective skin-cerumen barrier, followed by the subsequent inflammation, swelling, and obstruction of the canal, and impaired cerumen production are all factors in the development of acute otitis externa.
- AOE, infectious etiology (3):
- Bacterial infection (>90%): P. aeruginosa (22–62%), S. aureus (11–34%); polymicrobial infection is common.
- Fungal infection (<10%, more commonly associated with chronic otitis externa): Aspergillus (60–90%), Candida spp. (10–40%)
- Chronic otitis externa: often occurs due to inadequately treated acute otitis externa, persistent allergies, or chronic skin conditions (2).
- Eczematous otitis externa (associated with primary skin disorder)
- Eczema, seborrhea, psoriasis
- Contact dermatitis
- Purulent otitis media
- Sensitivity to topical medications
- Malignant (necrotizing) otitis externa (1)
- Invasive bacterial infection: Pseudomonas, increasing incidence of methicillin-resistant S. aureus (MRSA)
- Associated with patients with diabetes mellitus (DM) or immunosuppression
- Acute and chronic otitis externa
- Water exposure—typically swimming in fresh water
- Trauma to the external canal—cleaning, scratching, use of instruments
- Hot, humid weather
- Use of external devices—hearing aids, ear plugs
- Dermatologic conditions—eczema, seborrhea, psoriasis
- Anatomic abnormalities—narrow canal, exostoses
- Cerumen buildup
- Previous ear surgery
- Previous local radiotherapy
- Eczematous: primary skin disorder
- Necrotizing otitis externa in adults
- Advanced age
- Immunosuppression (e.g., AIDS, malignancy)
- 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
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