Outer Ear Infections (Otitis Externa)
Otitis externa — infection or inflammation of the skin of the outer ear canal — is one of the most common conditions seen in ENT practice and in general practice. It is particularly prevalent in warm, humid climates and in water sports participants, and it ranges in severity from mild irritation to a profoundly painful, swollen canal that makes even the lightest touch unbearable. Understanding its mechanisms, the important role of ear canal microsuction in treatment, and the specific situations that require urgent attention is important for any patient with this condition.
The Ear Canal Environment
The external ear canal is a bony and cartilaginous tube approximately 25mm in length that leads from the pinna to the eardrum. Its skin is specialised: thin, tightly adherent to the underlying bone in the inner two-thirds, and equipped with a remarkable self-cleaning mechanism. Epithelial cells on the eardrum and canal skin migrate outward at approximately the same rate that a fingernail grows — continuously carrying wax, debris, and skin cells toward the canal opening. This epithelial migration, combined with the natural acidic pH of the canal (approximately pH 6.1) and the antimicrobial properties of cerumen (earwax), creates a highly effective barrier against infection under normal circumstances.
Otitis externa occurs when this protective environment is disrupted. The two most common disruptions are moisture and trauma.
Causes and Predisposing Factors
Moisture and Water Exposure
Water entering the ear canal raises humidity, softens the keratin layer of the canal skin, reduces the protective acidity, and creates conditions favourable to bacterial and fungal overgrowth. This explains the high prevalence of otitis externa in swimmers — earning it the colloquial name “swimmer’s ear”. Even repeated showering without drying the ear canal can be sufficient to precipitate an episode in susceptible individuals. The risk is compounded in warm climates where the ambient humidity is higher.
Mechanical Trauma
The skin of the ear canal is thin and delicate. Inserting any object — cotton buds (cotton swabs), fingernails, pen caps, hairpins — disrupts the epithelial migration pattern, removes protective cerumen, creates micro-abrasions through which bacteria can enter, and can push debris deeper into the canal. Cotton buds are the single most common preventable cause of ear canal problems and should never be inserted into the ear canal. Their use is specifically designed for the outer ear only. Earplugs and hearing aids, when not properly fitted or cleaned, can also cause localised trauma and maceration.
Skin Conditions
Eczema, psoriasis, seborrhoeic dermatitis, and contact dermatitis affecting the ear canal skin impair the barrier function of the epithelium and predispose to secondary bacterial or fungal infection. Patients with these conditions may have recurrent or chronic otitis externa that requires a different management approach from acute infections in normal skin.
Exostoses
Bony growths (exostoses) within the ear canal — developed over years from cold water exposure in surfers and cold-water swimmers — narrow the canal and trap water and debris behind them, predisposing to recurrent otitis externa. This is one of the primary indications for exostosis surgery. Read more about exostoses →
Immunocompromise and Diabetes
Patients with diabetes mellitus or immunosuppression are at risk of a particularly severe and potentially life-threatening form of otitis externa called malignant (necrotising) otitis externa. This is caused by Pseudomonas aeruginosa and spreads beyond the canal skin into the underlying bone, potentially extending to the skull base and intracranially. It presents with severe, disproportionate otalgia, otorrhoea, and in advanced cases cranial nerve palsy. Any diabetic patient with severe or persistent otitis externa that does not respond to standard treatment should be assessed urgently for this condition.
Microbiology
The most common causative organisms in acute bacterial otitis externa are Pseudomonas aeruginosa and Staphylococcus aureus, together accounting for the majority of bacterial cases. These organisms are virtually ubiquitous in warm, moist environments and can establish infection rapidly in a compromised canal. Polymicrobial infections are common.
Fungal otitis externa (otomycosis) accounts for approximately 10% of otitis externa cases and is caused most commonly by Aspergillus species and Candida. It is more prevalent in tropical climates, following prolonged antibiotic ear drop use (which disrupts the normal bacterial flora), and in immunocompromised patients. Fungal otitis externa has a characteristic appearance — fluffy white, black, or yellow debris with visible fungal hyphae — and requires different treatment from bacterial infection. Standard antibiotic ear drops are ineffective against fungal infection; antifungal treatment (clotrimazole or itraconazole drops or powder) is required.
Symptoms
- Ear pain (otalgia): The cardinal symptom. Typically begins as mild itching or discomfort and rapidly progresses to severe, constant pain. The pain is disproportionately severe relative to the clinical appearance because the bony ear canal is inelastic — even mild oedema of the canal skin generates significant pressure. Pain is worsened by chewing, yawning, and by any movement of the pinna or pressure on the tragus.
- Itch: Characteristically precedes pain in the early stages. Scratching worsens the situation by further traumatising the canal skin.
- Discharge (otorrhoea): Initially clear and watery, progressing to mucopurulent as the infection establishes. In fungal infection, the discharge may be thick and white or black with visible fungal material.
- Hearing loss: Conductive hearing loss from canal oedema and debris occlusion. Usually mild to moderate and resolves as the infection clears.
- Tragal tenderness: Pain on pressing the tragus (the small cartilaginous projection in front of the ear canal opening) is a classic sign of otitis externa, distinguishing it from middle ear infection (otitis media) where the eardrum is the site of pathology.
Why Microsuction is Essential
The fundamental problem in established otitis externa is that the ear canal is filled with infected debris, exfoliated keratin, inflammatory cells, and thick secretions — and ear drops cannot penetrate through this material to reach the infected skin. Applying antibiotic drops to a blocked ear canal is like trying to treat a wound through layers of dressing. Unless the canal is cleaned first, ear drops will have limited effect and the infection will persist despite treatment.
Dr Roth uses a microscope and gentle suction (microsuction) to remove all infected material from the ear canal under direct vision, cleaning down to the eardrum and all aspects of the canal skin. This single step typically provides dramatic relief of pain — the release of pressure from the swollen canal skin is immediate — and allows ear drops to reach the entire canal surface. A swab is taken in resistant or recurrent cases to identify the specific organism.
Where significant swelling of the canal skin is preventing drops from remaining in contact with the canal, an Otowick (a small compressed sponge wick pre-soaked in antibiotic/steroid solution) may be placed in the canal. As the wick absorbs moisture from the canal secretions, it expands and holds the medication in contact with the inflamed skin, acting as a slow-release delivery system. The wick is removed at the next visit — usually 24–48 hours later.
Prevention
- Do not insert anything into the ear canal — including cotton buds. The ear canal is self-cleaning and does not require manual cleaning in most people. Any visible wax at the canal opening can be gently wiped away with a face cloth.
- Keep the ear canal dry — after swimming, tip the head from side to side and gently tug the outer ear to encourage water drainage. Use a hair dryer on a low, cool setting held at arm’s length to dry the canal.
- Use Aqua-Ear or similar acidifying drops after swimming for patients prone to recurrent otitis externa — these preparations restore the normal acidic pH of the canal.
- Wear well-fitting earplugs or a swim band when swimming if prone to recurrent infections.
- Manage underlying skin conditions — eczema and psoriasis affecting the ear canal require treatment from a GP or dermatologist to reduce the frequency of secondary infections.
- Clean hearing aids and earplugs regularly and ensure earplugs are the correct size.
Contact us to arrange a consultation → | Exostoses (Surfer’s Ear) → | Hearing Loss →
Dr Roth’s Clinical Perspective
Otitis externa is straightforward to treat when correctly diagnosed — topical antibiotic and steroid drops work reliably for uncomplicated bacterial infection. The management pitfall I see most often is inadequate aural toilet before instilling drops: a canal that is full of infected debris will not allow the drops to reach the infected epithelium, and the patient will not respond. Microsuction under the microscope to clear the canal before commencing drops is standard in our practice for anything more than mild disease, and it significantly accelerates resolution. The other important distinction is malignant otitis externa — necrotising infection in the immunocompromised or diabetic patient — which requires IV antibiotics and aggressive management, not topical treatment.
— Dr Jason Roth, MBBS, FRACS (ORL-HNS), IBCFPRS
Specialist Otolaryngologist & Head and Neck Surgeon
Specialist registration — Otorhinolaryngology, Head & Neck Surgery
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