Otomycosis (fungal otitis externa)
A fungal infection of the ear canal, often after antibiotic ear drops, swimming or in hot humid weather. It causes intense itch, a blocked ear and debris.
What it is
Superficial fungal infection of the external acoustic meatus, usually by Aspergillus or Candida species. It is a common form of otitis externa in hot, humid climates and is often missed and treated repeatedly with antibacterial drops.
Who gets it
It accounts for roughly one in ten cases of otitis externa, and more in tropical and subtropical regions such as much of Colombia, in swimmers, and in people who have used antibiotic or steroid ear drops for a long time.
Causes
- Aspergillus niger (black spores) and other Aspergillus species
- Candida albicans and other Candida species (white, creamy debris)
- Prolonged antibacterial or corticosteroid ear drops that disturb the canal's normal flora
- Moisture and heat: swimming, humid climates, sweating
Risk factors
- Prolonged use of antibiotic or steroid ear drops
- Hot, humid climate and swimming
- Diabetes mellitus, HIV or other immunosuppression
- Chronic suppurative otitis media or an open mastoid cavity
- Hearing aids and canal trauma from cotton buds
- Chronic dermatitis of the canal (eczema, seborrheic dermatitis)
Pathophysiology
Loss of the acidic, waxy protective layer and moisture that macerates the canal skin let saprophytic fungi colonise and invade the superficial keratin. Fungal hyphae and debris build up and can block the canal; inflammation is usually milder than in bacterial otitis externa. In immunosuppressed patients Aspergillus can rarely invade deeper tissue and bone.
Classification
- By organism: Aspergillus (filamentous fungus) or Candida (yeast)
- Canal infection only, or with eardrum perforation or a mastoid cavity
- Invasive fungal otitis (rare, in immunosuppressed patients)
Symptoms and signs
- Intense itch (the dominant symptom)
- Fullness or a blocked ear
- Mild to moderate ear pain
- Scant discharge
- Conductive hearing loss from debris
- Tinnitus
Diagnosis
- Clinical
- Otoscopy is usually diagnostic: wet, newspaper-like or cotton-wool debris with fine hyphae, and black, grey or green dots of spores (Aspergillus niger looks like black dots on white fluffy material); Candida gives white, creamy debris. It is suspected when otitis externa does not improve with antibiotic drops.
- Tests
- Potassium hydroxide (KOH) mount and fungal culture of the debris confirm the organism in recurrent or resistant cases; bacterial culture when a mixed infection is suspected.
- Imaging
- Not needed, unless invasive or necrotizing infection is suspected (CT of the temporal bone).
Differential diagnosis
- Bacterial otitis externa
- Necrotizing otitis externa
- Chronic otitis media with discharge
- Cerumen impaction
- Contact or seborrheic dermatitis of the canal
- Carcinoma of the ear canal
Goal of treatment
Clear the fungal debris, restore a dry, acidic canal and eradicate the fungus.
Treatment
- Procedure
- Thorough cleaning of the canal (aural toilet by microsuction or dry mopping) is the key step and often needs repeating every few days.
- Medical
- Topical antifungals such as clotrimazole drops or cream, or acidifying drops; with a perforation, a non-ototoxic agent such as clotrimazole is preferred. Antibacterial drops are stopped.
- Medical
- Oral antifungals (for example itraconazole or voriconazole) only for invasive disease or severe infection in immunosuppressed patients, under specialist care.
- Lifestyle
- Keeping the ear dry (protection when bathing or swimming), avoiding cotton buds and avoiding long unsupervised courses of ear drops prevent recurrence.
- Follow-up
- Referral to otolaryngology for microsuction when the canal cannot be cleaned, with a perforation, in diabetic or immunosuppressed patients with severe pain, and when it recurs or fails treatment.
Complications
- Recurrence (common)
- Eardrum perforation
- Secondary bacterial infection
- Invasive fungal otitis or necrotizing otitis externa in immunosuppressed patients
Prognosis
Good with cleaning and topical antifungals, though it often recurs if the predisposing factors persist.
Test yourself
Think of the answer, then tap the question to see it.
What is the classic otoscopic finding of Aspergillus niger otomycosis?
Fluffy white material with black dots (spores), like wet newspaper, filling the ear canal.
Which symptom dominates in otomycosis, unlike bacterial otitis externa?
Intense itch; pain is usually milder.
Which history should raise suspicion of otomycosis?
Otitis externa that does not improve after prolonged antibiotic or steroid ear drops, especially in a hot, humid climate or a swimmer.
What is the most important step in treating otomycosis?
Thorough cleaning of the ear canal (aural toilet), followed by a topical antifungal such as clotrimazole.
In ENT
- External ear problems: wax, otomycosis, furuncle, perichondritis, exostoses and keratosis obturans
- ENT medicines: ear drops, nasal sprays, decongestants and gargles
Connections
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Otitis Externa (StatPearls (NCBI Bookshelf), 2023).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.