The external auditory canal (EAC) is warm and dark making it conducive for bacteria and fungus. Otitis externa (OE) is an inflammation or localised infection of the EAC usually treated effectively topically rather than with systemic medications.
ED: Handled correctly, this supposedly simple problem resolves quickly. Clearance of the EAC is key as is avoidance of triggers.
Pathophysiology
The common causes of OE are water exposure (e.g. swimming), moisture (e.g. hearing aid use), insertion of foreign bodies, trauma, and dermatological conditions (e.g. dermatitis).
OE can be acute or chronic bacterial or fungal infections: Pseudomonas aeruginosa and Staphylococcus aureus are the commonest bacteria; 10% are fungal with Aspergillus being the most common, then Candida.
The presenting symptoms are pain, discharge, erythema and oedema of the EAC, hearing loss, cellulitis and lymphadenopathy.
Malignant OE is a severe infection that has spread to the soft tissues surrounding the EAC and can lead to temporal bone osteomyelitis. This life-threatening complication, with high mortality, is found more in the elderly or immunocompromised. It may present with severe deep pain out of proportion to clinical finding and granulation tissue on the floor of EAC.
Elderly or immunocompromised patients with severe ear pain should be referred for urgent ENT review to rule out malignant OE. It is also important to ensure other causes of ear discharge e.g. otitis media are not missed.
Treatment
Treatment revolves around pain control, removal of infected debris, topical antibiotic drops and avoidance of any trigger factors.
Pain control with adequate analgesia is essential. Very often the infected debris and mucous in the EAC is best cleaned by suctioning under direct vision. Once the EAC is cleaned, topical antibiotic drops are administered for up to three days after the symptoms settle. A wide variety of antibiotic drops are available; quinolone ear drops are effective and safe to use with no risk of ototoxicity.
If the EAC is oedematous and narrowed, a wick my need to be inserted. A wick aids the administration of ear drops to treat infection. If a wick is inserted, the ear should be suctioned clean and examined every 2 to 5 days, until the EAC oedema settles.
Avoid potential causes of OE such as water exposure by keeping the ear dry.
Oral antibiotics are seldom required unless if there is cellulitis or lymphadenopathy.
Prevention
Avoiding the causes of OE will reduce recurrences. Water activities should be stopped for 1 to 2 weeks after the infection has gone. Ear plugs and or swimming caps should be used as a shield from water.
Avoiding moisture and trauma to the EAC minimises recurrence. Water or moisture trapped in the EAC can be dried with a hairdryer.
Key Messages
- Otitis externa is common and treatment mainly topical
- Beware malignant OE and refer promptly
- Prevention measures can reduce recurrence
Author competing interests: nil relevant disclosures.
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