Acute Otitis Externa

Clinical Notes : ENT

126. Acute Otitis Externa

Acute Otitis Externa

Topical preparations available in the ROI

- References -

- CPD Quiz -

Definition

Otitis externa is inflammation of the external ear canal
- Acute if it has lasted for 3 weeks or less.
- Chronic if it has lasted for longer than 3 months.

Diffuse (swimmer's ear, or tropical ear)
- widespread inflammation of the skin and subdermis of the external ear canal, which can extend to the external ear and the tympanic membrane (ear drum)

Localized (furunculosis)
- infection of a hair follicle that can progress to become a furuncle (boil) in the ear canal

Eczematous (eczematoid)
- Encompasses various dermatologic conditions that may infect the External Auditory Canal
  - atopic dermatitis
  - psoriasis
  - systemic lupus erythematosus
  - eczema

Necrotising (malignant)
- aggressive infection that spreads into the bone surrounding the ear canal (the mastoid and temporal bones
  - fatal condition without treatment

Otomycosis
- Infection of the ear canal from a fungal species

Incidence

Otitis externa is common and more than 1% of people will be diagnosed with the condition each year.
- It affects people of all ages, but incidence peaks at age 7–12 years.

Etiology

Bacterial infection
- most common cause of otitis externa
- Pseudomonas aeruginosa or Staphylococcus aureus are the most prevalent pathogens.

Fungal infections
- Superficial fungal infection is usually due to Aspergillus species, or Candida albicans.
- Deeper infections (of the stratum corneum) are due to epidermophyton, trichophyton, or microsporum genera.

Seborrhoeic dermatitis
- may affect the ears in isolation, or be associated with one or more of the following: dandruff, eyebrow scaling, blepharitis, or facial redness and scaling.

Contact dermatitis
- topical medications (for example neomycin ear drops)
- hearing aids
- earplugs.

Allergic contact dermatitis
- usually has a sudden onset and presents with erythematous, itchy, oedematous, and exudative lesions.

Irritant contact dermatitis
- tends to have an insidious onset with lichenification.

Trauma
- caused by scratching, aggressive cleaning, ear syringing, foreign objects in the ear, and the use of cotton buds, hearing aids or ear plugs.

Environmental factors
- high temperature and/or high humidity
- perspiration
- swimming (especially in polluted water)

Regular cleaning of the ear canal
- alkaline eardrops
- soapy deposits
- cerumen creates a slightly acidic pH that inhibits infection (especially by P aeruginosa) but can be altered by water exposure, aggressive cleaning
- removes cerumen, which is an important barrier to moisture and infection

Risk factors for malignant otitis include
- diabetes
- radiotherapy to the head and neck.
- compromised immunity, such as from HIV/AIDS, chemotherapy, or chronic kidney disease

Diagnosis

Signs:
- The ear canal or external ear, or both, are red, swollen, or eczematous with shedding of the scaly skin.
- Swelling in the ear canal is typical of an early presentation of localized otitis externa; later the swelling has a white or yellow centre filled with pus; occasionally this progresses and the swelling eventually completely occludes the ear canal.
- Discharge (serous or purulent) may be present in the ear canal.
- Inflamed eardrum, which may be difficult to visualize if the ear canal is narrowed or filled with debris.

Symptoms include any combination of the following:
- Itch (typical).
- Severe ear pain, disproportionate to the size of the lesion (typical).
- Pain made worse when the tragus or pinna is moved, or when an otoscope is inserted (typical).
- Tenderness on moving the jaw.
- Tender regional lymphadenitis — may be present (less common).
- Sudden relief of pain if the furuncle in localized otitis externa bursts (rare).
- Loss of hearing if there is sufficient swelling to occlude the ear canal (rare).

Diffuse (swimmers ear)

Localised (furunculosis)

Eczematoid

Malignant

Otomycosis

Management

Treat the pain if present:
- analgesic
  - paracetamol or ibuprofen
  - plus codeine for severe pain
- application of local heat (for example a warm flannel).
- These measures are sufficient for most cases of localized otitis externa as folliculitis is usually mild and self-limiting

Topical antimicrobials are beneficial
- use topical antibiotic with or without a topical corticosteroid
- use for a minimum of 7 days
  - if symptoms persist, continue up to a maximum of 14 days
- Quinolone containing preparations (for example ciprofloxacin, or ofloxacin) only require twice daily dosing
  - can be used in people with a perforated ear drum
- Topical acetic acid 2% spray
  - is safe and effective treatment
  - can be used for mild cases
- Chloramphenicol ear drops
  - not recommended as they contain propylene glycol which causes contact dermatitis in about 10% of people

Only consider an oral antibiotic if
- medical condition which is associated with increased risk of severe infection (such as diabetes mellitus, or compromised immunity).
- systemic signs of infection, such as fever.
- severe infection, or at high risk for severe infection
  - for example if furunculosis or cellulitis spreads beyond the ear canal to the pinna, neck, or face.
- If an oral antibiotic is required, consider are a 7-day course of flucloxacillin, or clarithromycin (if the person is allergic to penicillin)

If fungal infection is suspected (signs of fungal growth in the ear canal):
- Prescribe a topical antifungal preparation
  - Clotrimazole 1% solution.
  - Acetic acid 2% spray (unlicensed use).
  - Clioquinol and a corticosteroid
- Seek specialist advice if there is inadequate response.

If the cause is Irritant, or allergic dermatitis
- avoid contact with the irritant or allergen
- prescribe a topical corticosteroid.
  - Seborrhoeic dermatitis — treat topically with an antifungal/corticosteroid combination

Drain pus
- if pus is causing severe pain and swelling
  - rarely required.
  - usually requires referral
    - a small pustule near the entrance to the ear canal may be drained by incising it with a surgical needle

Manage any aggravating or precipitating factors
- diabetes mellitus
- dermatitis
- ear trauma

Consider the need for investigations
- ear swab proves rarely useful, but may be necessary if symptoms are persistent or recurrent.

Provide appropriate self-care advice to aid recovery and reduce risk of recurrence
- keep the ears clean and dry
- avoid the use of cotton buds

Treat generalized skin conditions such as eczema

Seek specialist advice if
- symptoms persist
- contact sensitivity is suspected
- ear canal is occluded.

Refer to secondary care if
- extensive cellulitis
- extreme pain or discomfort
- considerable discharge or extensive swelling of the auditory canal
- sufficient earwax or debris to obstruct the application of topical medication

Follow up
- is not usually necessary,
- recommended for people with
  - severe otitis externa
  - chronic otitis externa
  - diabetes mellitus
  - compromised immunity.

Management of localized otitis externa includes:
- Advising people to apply local heat using a warm flannel — this may be sufficient, as folliculitis is usually mild and self-limiting.
- Considering incision and drainage if pus is causing severe pain and swelling — this usually requires referral, although a small pustule near the entrance to the ear canal may be drained by incising it with a surgical needle.

Urgent admission should be arranged for people with suspected malignant otitis.

Self-care

Keep ears clean and dry
- avoid use of cotton buds
- use a hair dryer (at the lowest heat setting) to dry the ear canal after hair washing, bathing, or swimming
- swimming
  - use ear plugs and or a tight fitting cap
  - people with acute otitis externa should abstain from water sports for at least 7 to 10 days
  - consider using acidifying ear drops or spray (such as EarCalm®) shortly before swimming, after swimming, and at bedtime