Key Points
Î Acute otitis externa (AOE) is a cellulitis of the ear canal skin and subdermis,
with acute inflammation and variable edema.
Î Also known as swimmer's ear or tropical ear, AOE is one of the most
common infections encountered by clinicians, with regional variations based
on age and geography.
Î In 2007 there were about 2.4 million visits to ambulatory care centers and
emergency departments for AOE (8.1 visits per 1000 population), affecting
1 in 123 persons in the United States.
• Just less than half of all visits were for children 5-14 years of age.
• Lifetime incidence is up to 10%.
• AOE is more common in regions with warmer climates, increased humidity, or increased
water exposure from swimming.
• Nearly all (98%) AOE in North America is bacterial.
Î The etiology of AOE is multifactorial.
• Regular cleaning of the ear canal removes cerumen, which is an important barrier to
moisture and infection.
• Debris from dermatologic conditions may also encourage infections, as can local trauma
from attempts at self-cleaning, irrigation, and wearing hearing aids.
• Other factors such as sweating, allerg y, and stress have also been implicated in the
pathogenesis of AOE.
Î The most common pathogens are Pseudomonas aeruginosa (20%-60%
prevalence) and Staphylococcus aureus (10%-70% prevalence), often
occurring as a polymicrobial infection.
Î Topical antimicrobials are beneficial for AOE, but oral antibiotics have
limited utility.
Table 1. Elements of the Diagnosis of Diffuse Acute Otitis Externa
1. Rapid onset (generally within 48 hours) in the past 3 weeks, AND…
2. Symptoms of ear canal inflammation, which include:
• otalgia (often severe), itching, or fullness
• WITH OR WITHOUT hearing loss or jaw pain
a
, AND…
3. Signs of ear canal inflammation, which include:
• tenderness of the tragus, pinna, or both
• OR diffuse ear canal edema, erythema, or both
• WITH OR WITHOUT otorrhea, regional lymphadenitis, tympanic membrane
erythema, or cellulitis of the pinna and adjacent skin.
a
Pain in the ear canal and temporomandibular joint region intensified by jaw motion.
Diagnosis
