Acute otitis externa (AOE) is a diffuse inflammation of the external ear canal that is most commonly caused by Pseudomonas aeruginosa and Staphylococcus aureus.
Presents with rapid onset of ear pain, tenderness, itching, aural fullness, and hearing loss.
More common in children and young adults.
Fungal otitis externa is a fungal infection of the external ear caused by molds and yeasts, which presents in a similar way to acute bacterial otitis externa.
Necrotizing otitis externa infection (also called malignant otitis externa) involves skin and soft tissue of the external auditory canal and bone tissue of the temporal bone.
Treatment of the uncomplicated form is cleaning of the ear canal and application of topical anti-infective agents. Oral antibiotics may be required for patients with diabetes, those who are immunocompromised, or those who do not respond to initial topical treatment. Necrotizing otitis externa is a medical emergency requiring prompt treatment with debridement of necrotic tissue and oral or intravenous antibiotics.
AOE is defined as diffuse inflammation of the external ear canal, which may also involve the pinna or tympanic membrane. It is a form of cellulitis that involves the skin and subdermis of the external auditory canal, with acute inflammation and variable edema. It is most commonly caused by bacterial infection with Pseudomonas aeruginosa or Staphylococcus aureus. National guidelines state that a diagnosis of AOE requires the presence of rapid onset (generally within 48 hours) of symptoms within the past 3 weeks, coupled with signs of ear canal inflammation.
History and exam
Key diagnostic factors
- ear pain
- tenderness over the tragus, pinna, or both
- ear canal swelling and erythema
- granulation tissue in the ear canal (necrotizing otitis externa)
Other diagnostic factors
- aural fullness
- decreased hearing
- pain intensified by jaw motion
- erythematous tympanic membrane
- cellulitis of the pinna and adjacent skin
- external auditory canal obstruction
- high environmental humidity
- warmer environmental temperatures
- local trauma
- chemical irritants
- skin disease
- prolonged use of topical antibacterial agents
1st investigations to order
- pneumatic otoscopy
Investigations to consider
- ear culture
- microscopy of exudate/debris from ear canal
- CT scan of the temporal bone with intravenous contrast
- MRI of the brain and internal auditory canals (with and without gadolinium)
- erythrocyte sedimentation rate (ESR)
- Acute otitis media
- Contact dermatitis of the ear canal
- Clinical practice guideline: acute otitis externa
- Practice point: acute otitis externa
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