Otitis Externa
Basics
Description
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
Epidemiology
Incidence
- 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)
Prevalence
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
Risk Factors
- 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
- DM
- Immunosuppression (e.g., AIDS, malignancy)
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
There's more to see -- the rest of this topic is available only to subscribers.
Citation
Domino, Frank J., et al., editors. "Otitis Externa." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2020. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688572/all/Otitis_Externa.
Otitis Externa. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2020. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688572/all/Otitis_Externa. Accessed December 10, 2023.
Otitis Externa. (2020). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (27th ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688572/all/Otitis_Externa
Otitis Externa [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2020. [cited 2023 December 10]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688572/all/Otitis_Externa.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC
T1 - Otitis Externa
ID - 1688572
ED - Domino,Frank J,
ED - Baldor,Robert A,
ED - Golding,Jeremy,
ED - Stephens,Mark B,
BT - 5-Minute Clinical Consult, Updating
UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688572/all/Otitis_Externa
PB - Wolters Kluwer
ET - 27
DB - Medicine Central
DP - Unbound Medicine
ER -