Definition and General Features
External Ear Canal Infection (Otitis Externa, OE) is defined as a diffuse inflammation of the skin and subcutaneous tissue of the external auditory canal, sometimes involving the auricle or the tympanic membrane.
One of the most important criteria for diagnosis is that the symptoms and signs of ear canal inflammation have appeared within the last 3 weeks, with an acute onset (usually within 48 hours).
This acute inflammatory reaction causes varying degrees of edema and pain in the ear canal. OE is rare before the age of two, and there is very limited evidence regarding treatment and outcomes in this age group. Therefore, this article focuses on the diagnosis and treatment of patients over the age of two.
Also known as “Swimmer’s Ear” or “Tropical Ear”, OE is one of the most common infections encountered by clinicians, showing regional variations depending on age and geography.
Approximately half of all cases occur between June and August, and the incidence drops significantly in winter months.
In coastal regions like Antalya, it is among the most common infections during the summer season.
Roughly 50% of all hospital visits occur among children aged 5 to 14, and the lifetime incidence can reach up to 10%.
Table 1. Diagnostic Criteria for Acute Diffuse Otitis Externa
-
Rapid onset within the last 3 weeks (usually within 48 hours)
AND -
Symptoms related to external ear canal inflammation:
-
Ear pain (often severe), itching in the ear, a feeling of fullness
-
Hearing loss associated with ear pain or jaw movement pain
-
AND
-
Findings of external ear canal inflammation:
-
Severe pain when pressing on the tragus (the small triangular cartilage in front of the ear canal) or pulling the auricle
-
Diffuse redness or swelling of the external canal
-
May occur together or alone with ear discharge, painful enlargement of neck lymph nodes, redness of the eardrum, or cellulitis around the ear and surrounding skin.
Symptoms
Symptoms of OE include otalgia (ear pain) (~70%), itching (~60%), fullness sensation (~22%), hearing loss (~32%), or jaw movement-related pain.
A distinguishing feature is pain or tenderness when the tragus is pushed or the auricle is pulled backward.
Examination reveals ear discharge, diffuse canal edema, and erythema.
In some cases, swelling and redness may extend to the auricle and surrounding skin, and painful lymph node enlargement in the upper neck may occur.
Microbiology
Almost all (~98%) cases of Otitis Externa are bacterial in origin.
The most common pathogens are Pseudomonas aeruginosa (20–60%) and Staphylococcus aureus (10–70%), often forming polymicrobial infections.
Other pathogens include non-Pseudomonas gram-negative organisms (2–3%).
Fungal infections are rare in primary OE but may occur in chronic cases or after topical/systemic antibiotic use during treatment.
Predisposing Factors for External Ear Canal Infection
OE can arise from many causes.
Regular cleaning of the ear canal removes cerumen, commonly known as “earwax,” which actually acts as a natural protective barrier against moisture and infection (especially against P. aeruginosa).
Cerumen maintains a slightly acidic environment, which inhibits bacterial growth. However, water exposure, aggressive cleaning, soap residues, or alkaline ear drops can disrupt this protective acidity.
Dermatologic debris, use of cotton swabs, exposure to water after showers or swimming, and prolonged use of hearing aids or earphones all facilitate infection.
OE is more common in hot and humid climates, and exposure to seawater or pool water increases risk. Even when water quality meets standards, it may still harbor infectious agents. Some individuals (e.g., with blood type A) may be genetically predisposed to OE.
Dermatologic conditions (eczema, seborrheic dermatitis, psoriasis), anatomic abnormalities (narrow ear canal, bony protrusions), or chronic otitis media with discharge may also contribute to susceptibility.
Prevention Strategies
Prevention aims to minimize water retention and maintain a healthy skin barrier in the ear canal. Strategies include:
-
Physician-assisted removal of obstructive cerumen if necessary.
-
Use of acidifying ear drops before/after swimming or before bedtime.
-
Drying the canal gently with a low-setting hair dryer.
-
Earplugs while swimming.
-
Avoiding trauma from cotton swabs or foreign objects.
Differential Diagnosis
OE must be differentiated from other causes of ear pain (otalgia) or ear discharge, such as:
-
Chronic Otitis Externa
-
Malignant Otitis Externa
-
Acute/Chronic Otitis Media
OE can mimic Acute Otitis Media (AOM) due to eardrum redness and pain, but pneumatic otoscopy and tympanometry can distinguish them:
-
AOM shows limited tympanic membrane mobility (flat “Type B” curve).
-
OE shows normal mobility (Type A curve).
Dermatologic conditions such as eczema, seborrheic dermatitis, or contact dermatitis (from metals, shampoos, plastics, etc.) can also mimic OE.
The most common allergen is nickel, affecting about 10% of women with pierced ears.
Figures and Skin Conditions
Figure 1: Erythema, xerotic scaling, and lichenification indicating dermatitis — should be distinguished from OE.
Figure 2: Seborrheic dermatitis with Malassezia yeast — characterized by oily yellow scaling, itching, and inflammation. Common in patients with Down syndrome, HIV, or Parkinson’s disease.
Treatment involves topical antifungal and anti-inflammatory agents.
Other mimicking conditions include psoriasis and discoid lupus erythematosus.
Contact dermatitis can be irritant (from acids/alkalis) or allergic (metals, soaps, shampoos, hearing aids).
Neomycin-containing drops are the most common culprits, causing allergic reactions in 5–15% of chronic otitis externa patients.
Treatment of External Ear Infection
1. Pain Management
Pain control is one of the most critical aspects of OE treatment.
Pain occurs because the periosteum beneath the skin of the ear canal is highly sensitive.
Adequate analgesia should be started early and regularly, using:
-
NSAIDs for mild to moderate pain.
-
Opioids (e.g., oxycodone, hydrocodone) for severe pain.
Topical anesthetic drops (with or without antipyrine/benzocaine) may temporarily relieve pain but should not be used if tympanic membrane integrity is uncertain.
2. Antibiotic Therapy
Topical antibiotics are the first-line treatment for uncomplicated OE.
They achieve 100–1000x higher concentrations directly in infected tissue than systemic antibiotics.
Systemic antibiotics should only be used if:
-
Infection spreads beyond the ear canal (to auricle, face, or neck),
-
Patient has diabetes, immunodeficiency, or chronic otitis media.
Common topical agents:
-
Ofloxacin, Ciprofloxacin/Dexamethasone (FDA-approved for middle ear use).
-
Avoid Neomycin/Polymyxin B/Hydrocortisone if tympanic membrane is perforated (ototoxic risk).
3. Application of Ear Drops
-
Patient should lie on the opposite side (affected ear facing up).
-
Drops applied along the canal edge.
-
Move auricle gently to eliminate air and ensure coverage.
-
Remain in position for 3–5 minutes.
-
If canal is swollen, a wick may be placed for better penetration.
Outcome and Follow-up
Patients should be re-evaluated within 48–72 hours.
If pain or discharge persists, consider:
-
Incorrect diagnosis
-
Blocked ear canal (preventing drop absorption)
-
Poor compliance
-
Allergic reaction to the drops
-
Secondary fungal overgrowth due to prolonged antibiotic use.
With correct treatment, most patients experience significant pain relief within 24 hours and full recovery in 4–7 days.
Conclusion
Otitis Externa is a common acute infection, particularly in humid, warm climates and during summer months.
It is characterized by sudden onset and intense ear pain, but with proper diagnosis and management, clinical outcomes are excellent.
