Acute otitis externa 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.
The development of malignant or necrotising otitis externa is more common in diabetic and immunocompromised people.
Treatment of the uncomplicated form is cleaning of the ear canal and application of topical anti-infective agents.
Acute otitis externa (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 oedema. 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
- presence of risk factors
- ear pain
- tenderness over the tragus, pinna, or both
- ear canal swelling and erythema
- granulation tissue in the ear canal (malignant 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
Outer ear infection
Ear infection in children: questions to ask your doctorMore Patient leaflets
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