Otitis externa

Introduction

Otitis externa also called swimmers’ ear is an inflammation of the external ear
It may be:

  • Infective: bacteria or fungi
  • Reaction of the canal skin to chemical irritant(s)
  • Part of a generalized dermatitis

Localised otitis externa or furuncle (boil) is a Staphylococcal infection of a hair follicle in the canal.
Diffuse otitis externa may be bacterial or fungal or reactive.
May be acute or chronic

  • Bacterial infection often follows trauma from scratching the canal skin
  • Fungal otitis (otomycosis) commonly follows swimming in the tropics, usually infection by Aspergillus niger.

 

Symptoms and clinical features of Otitis externa

  1. Pain and itching
  2. Ear discharge
  3. Sensation of blockage due to accumulated debris in canal
  4. Deafness is variable
  5. Canal is red and swollen, full of inflammatory debris
    • In otomycosis whitish mass of debris with black spots

Differential diagnoses

Complications of Otitis externa

  • Acute perichondritis

Investigations

  • Ear swab, taken properly for microscopy, culture and sensitivity
  • Urinalysis for glycosuria
  • Blood glucose estimation in cases of recurrent furunculosis to exclude diabetes mellitus.

Treatment for Otitis externa

Treatment objectives

  • Control infection/inflammation
  • Relieve discomfort

Non-drug treatment

  1. Careful ear toilet to clear out debris
  2. Daily dressing with antiseptic gauze packed with Acriflavin in spirit
  3. Furunculosis: dressing with magnesium sulfate wick or steroid and antibiotic ointment dressing

Drug treatment

A. Antibiotics

Amoxicillin

  • Adult: 500 mg-1 g orally every 8 hours for 5-7 days
  • Child: 40 mg/kg orally in every 8 hours for 5-7 days.

Neomycin/hydrocortisone ear drops

  • Adult and child: instil 2-3 drops 3 – 4 times daily

B. Analgesics

Paracetamol

  • Adult: 500mg-1 g orally every 4-6 hours (to a maximum of 4 g) for 5-7 days
  • Child:
    • over 50 kg: same as adult dosing
    • 6-12 years: 250-500 mg;
    • 3 months-5 years: 125-250 mg taken orally every 4-6 hours

Supportive measures

  • Prevent water from entering ear for one month

Prevention of Otitis externa

  • Avoid trauma to ear canal (especially scratching)
  • Keep ears dry