Otitis externa affects as many as 10% of people in their lifetime
Infection of the external auditory canal occurs most often after moisture exposure or minor trauma to the ear canal. Bacterial causes (e.g., Pseudomonas aeruginosa, Staphylococcus aureus) account for most cases. Fungal pathogens (e.g., Aspergillus, Candida) contribute to about 10%.1
Clinical signs include pain when applying tragal pressure or manipulating the pinna
Patients typically present with acute otalgia, pruritus, aural fullness, or otorrhea. Otoscopy shows erythema and edema of the ear canal with debris or discharge.2
Red flags for necrotizing otitis externa require urgent referral
Severe or persistent otalgia, granulation tissue in the canal, pain disproportionate to findings on examination, infection extending beyond the ear canal, or cranial nerve deficits should prompt suspicion of necrotizing otitis externa and urgent referral to an otolaryngology—head and neck surgeon.1 Imaging should be done with contrast-enhanced computed tomography of the temporal bone. Patients who are older, immunocompromised, or have diabetes are at highest risk.3
Topical therapy is the first-line treatment for otitis externa
Antimicrobial ear drops, with or without corticosteroids to reduce inflammation, result in clinical resolution in 65% to 90% of patients within 7 to 10 days, with improvement often within 72 hours. Fluoroquinolone drops (e.g., 4 drops of 0.3% ciprofloxacin–0.1% dexamethasone otic, twice daily for 7 days) are commonly used and are safe in children and in cases where tympanic membrane perforation is suspected. Aminoglycoside preparations (e.g., tobramycin) are potentially ototoxic if membrane perforation has occurred.2
Treatment failure occurs most often when drug delivery is suboptimal
Ear canal edema or debris can prevent topical agents from reaching the infected skin. Aural toilet or wick placement may be needed, which may require referral to an otolaryngology—head and neck surgeon. Persistent symptoms despite appropriate therapy should prompt ear swabs to test for fungal infection and close examination for red flags.4
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Footnotes
Competing interests: None declared.
This article has been peer reviewed.
References
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