Most commonly caused by Pseudomonas aeruginosa and Staphylococcus species.
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. The 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. 
Ear, Nose and Throat Associates of New York
SG declares that she has no competing interests.
Professor Neurological Surgery
Chief of Pediatric Otology
Otolaryngology Head and Neck Surgery
UT Southwestern Medical Center
PSR has acted as a consultant to Alcon laboratories, makers of Ciprodex®, who have provided compensation to the University of Texas Southwestern Medical Center Department of Otolaryngology Head and Neck Surgery. PSR has received compensation for speaking and for organizing educational events. PSR is co-author of the American Academy of Head and Neck Surgery's practice guideline for AOE. PSR is an author of references cited in this monograph.
Emeritus Professor of Otolaryngology
UCL Ear Institute
AW declares that he has no competing interests.
Director ENT Unit
North Bristol NHS Trust
Honorary Reader in Otolaryngology
University of Bristol
DAN declares that he has no competing interests.
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