Otitis externa (OE) refers to an infection, either bacterial or fungal, of the external auditory canal.  Possible etiologic agents include Pseudomonas aeruginosa, Proteus mirabilis, Staphylococcus aureus, Candida albicans, Aspergillus niger, and Aspergillus versicolor.  Conditions which predispose to OE include activities which may cause prolonged exposure to wet conditions (swimming), humid climates, hearing aids, mechanical trauma to the auditory canal especially during cleansing with rigid tools, cerum impaction, and dermatologic conditions which compromise the cutaneous integrety of the auditory canal (psoriasis, eczema, folliculitis).  As with most infections, diabetics and immunocompromised patients are also prone to OE.  If symptoms include ear pain, hearing loss, and facial palsy, consider the Ramsay Hunt syndrome which occurs secondary to a flare of varicella zoster infection of the geniculate ganglion.

     Symptoms of OE include pain of the auditory canal which is exacerbated with pressure or movement of the outer ear.  There may be associated discharge from the ear, and hearing acuity may be decreased as the auditory canal becomes swollen and narrowed secondary to edema.  Otoscopic examination may show a purulent exudate or fungal hyphae with spores lining the auditory canal.  The auditory canal may appear stenotic on the affected side when compared to the unaffected side.  If granulation tissue is present, a more serious fulminant infection may be present.

     Cultures are generally unnecessary, and empiric therapy may be initiated with 2% glacial acetic acid plus an anti-inflammatory/antibiotic solution.  During the initial examination, debris of the auditory canal should be removed with curettage, irrigation, and suction.  Symptoms should begin to resolve after 48 hours of therapy, if symptoms are persistent or if the examination implicates a possible fungal etiology, either nystatin or tolnaftate powder or creams may be employed.  If there is an associated dermatosis, a steroid containing form of therapy may prove beneficial.  If the auditory canal is stenotic secondary to edema, a dry ear wick (Pope wick) should be inserted and the medication applied to the ear wick to allow capillary action to carry the medication deep into the canal.  Moderate to severe infections should be treated with systemic antibiotics which should provide antipseudomonal and antistaphylococcal coverage.  Fluoroquinolones either orally for moderate infections or intravenously for severe infections is a good initial choice.  Mild cases which persist despite therapy or severe cases warrant referral to an otolaryngologist.  For patients with recurrent symptoms, prophylactic therapy with isopropyl alcohol or 2% acetic acid after swimming may help decrease the frequency of infection.

     Diabetic and immunocompetent patients are prone to a more severe infection with associated scalp cellulitis and osteomyelitis of the skull known as necrotizing or malignant otitis externa.  Intravenous therapy with ciprofloxacin, ceftazidime, or the combination of an aminoglycoside (gentamicin) plus an antipseudomonal penicillin (pipercillin) are all effective forms of therapy and should be continued for one to two weeks.