Otitis Externa in Adults

Epidemiology and Etiology

Otitis externa affects adults more commonly than children, with a lifetime incidence of approximately 10% 1, 2
The primary causative organisms are bacterial, with Pseudomonas aeruginosa and Staphylococcus aureus accounting for a significant portion of cases in North America 3
Fungal infections are less common causes of otitis externa, with Aspergillus or Candida species being the typical pathogens 1, 3
"Swimmer's ear" is a common variant of otitis externa due to conversion of the normal acidic environment of the ear canal to alkaline from water exposure 1, 3

Characteristic symptoms of otitis externa include otalgia, tenderness, fever, and ear discharge 1
Pain can be intense and severe because the highly sensitive periosteum of the underlying bone is in close proximity to the ear canal skin 4

Furunculosis, an infected hair follicle in the outer third of the ear canal, presents with localized tenderness, focal swelling, and pustular lesions 5, 6
Viral infections, such as herpes zoster oticus/Ramsay Hunt syndrome, present with vesicles on the external ear canal and posterior auricle 5, 7
Temporomandibular joint syndrome is a common cause of referred ear pain in adults 5
Upper aerodigestive tract malignancies can cause referred ear pain, particularly in older patients with tobacco and alcohol use history 5

Contact dermatitis can mimic or coexist with otitis externa, presenting with similar symptoms 8, 7
Seborrheic dermatitis presents with greasy yellowish scaling and itching, and can be confused with otitis externa 8, 7
Cholesteatoma is typically painless, with tympanic membrane abnormalities, and can be distinguished from otitis externa 6

Pain relief is an essential component of managing otitis externa, and topical antibiotics can deliver antimicrobial concentrations 100-1000 times higher than systemic therapy 4, 3
Oral antibiotics should be reserved for cases with extension beyond the ear canal or in immunocompromised patients 3

Failure to recognize referred pain from non-ear sources can lead to missed diagnoses, particularly concerning for malignancies in adults with risk factors 5
Confusing otitis externa with otitis media can lead to inappropriate treatment 3
Persistent symptoms despite appropriate treatment should prompt consideration of resistant organisms, fungal infection, or underlying conditions 9
Necrotizing otitis externa is a serious complication in immunocompromised patients or those with diabetes that requires prompt recognition and treatment 1, 2