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Acute otitis externa

Definition
Acute otitis externa is defined as an infection of the cutis and subcutis of the external auditory canal, possibly involving the tympanic membrane and pinna as well.
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Pathophysiology
More than 90% of acute otitis externa cases are caused by bacteria, most commonly P. aeruginosa and S. aureus. Polymicrobial infection is common. Fungi are a rare cause of acute otitis externa.
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Epidemiology
The incidence of acute otitis externa in the US is estimated at 810 per 100,000 person-years.
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Disease course
The characteristic symptom of acute otitis externa is severe pain, which is typically worsened by pressure on the tragus or tension on the pinna. Other symptoms include otorrhea, itch, erythema, and swelling of the ear canal, potentially leading to conductive hearing loss. Inadequately treated acute otitis externa may lead to chronic otitis externa.
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Prognosis and risk of recurrence
Early diagnosis and rapid initiation of a 4- to 6-week course of antibiotics help lower the morbidity and mortality, but recurrence is common.
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Key sources
The following summarized guidelines for the evaluation and management of acute otitis externa are prepared by our editorial team based on guidelines from the Infectious Diseases Society of America (IDSA 2016) and the American Academy of Otolaryngology-Head and Neck Surgery Foundation (AAO-HNSF 2014).
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Guidelines

1.Diagnostic investigations

Assessment
Distinguish diffuse acute otitis externa from other causes of otalgia, otorrhea, and inflammation of the external ear canal.
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Assess the patient with diffuse acute otitis externa for factors that modify management (nonintact tympanic membrane, tympanostomy tube, diabetes, immunocompromised state, prior radiotherapy).
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2.Medical management

Systemic antibiotics: do not offer systemic antimicrobials as initial therapy for diffuse, uncomplicated acute otitis externa unless there is extension outside the ear canal or the presence of specific host factors that would indicate a need for systemic therapy.
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More topics in this section

  • Topical therapy

  • Pain management

3.Specific circumstances

Patients with Aspergillus otitis externa: perform mechanical cleansing of the external auditory canal and administer topical antifungals or boric acid in patients with noninvasive Aspergillus otitis externa.
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4.Follow-up and surveillance

Follow-up: reassess the patient who fails to respond to the initial therapeutic option within 48 to 72 hours to confirm the diagnosis of diffuse acute otitis externa and to exclude other causes of illness.
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