Otitis externa

OTITS EXTERNA
  • Inflammation of the ear canal with or without infection .
  • Two types:Acute Otits externa and Chronic Otitis Externa
  • If symptoms are recurrent or if they last longer than three months, the condition is classed as chronic otitis externa.
Acute otitis externa can be classified according to its cause.
  • These are split into three main groups:
  • Infective (bacterial, fungal, and viral),
In bacterial infection-
  • Pseudomonas aeruginosa and Staphylococcus aureus are the most commonly isolated organisms.
  • Less commonly isolated organisms include Proteus species, Staphylococcus epidermidis, diphtheroids, and Escherichia coli.
Viral infection:
  • Otitis externa haemorrhagica is most commonly caused by influenza virus and is characterised by formation of haemorrhagic bullae on the tympanic membrane.
Fungal infection(Otomycosis)
  • In 80% of cases, the etiologic agent is Aspergillus, whereas Candida is the next most frequently isolated fungus.
  • Other more rare fungal pathogens include Phycomycetes, Rhizopus, Actinomyces, and Penicillium.
  • Non-infective dermatitis (allergic, eczematous, and irritant), and 
  • Mixed infective and non-infective.
PREDISPOSING FACTORS OF OTITIS EXTERNA
  • Warm humid climates, swimming, frequent hair washing (especially if in the bath), and insertion of foreign bodies can introduce bacterial infection and cause local trauma to the ear canal, making infection more likely.
  • Prolonged use of hearing aids may also predispose to infection.
  • Humidity and hot climate are one of the predisposing factors for otitis externa. Hence - otitis externa is also k/a Singapore ear (where climate is hot & humid) or Telephonist ear as talking on phone causes humidity around ear) or Swimmers ear.
  • Patients with diabetes are susceptible to otitis externa.
CLINICAL FINDINGS:
  • Ear pain, pruritus, and discharge.
  • On examination, the ear canal is erythematous and edematous.
  • Tenderness to manipulation of the external ear present.
Exam Question
  • Otomycosis is most commonly caused by Aspergillus Fungus and then Candida fungus.
  • Patients with diabetes are susceptible to otitis externa.
  • Findings of Otits externa:ear pain, pruritus, and discharge. On examination, the ear canal is erythematous and edematous. Tenderness to manipulation of the external ear present.
  • Exacerbating factors of Otits externa include: Warm humid climates, swimming, frequent hair washing (especially if in the bath), and insertion of foreign bodies can introduce bacterial infection and cause local trauma to the ear canal, making infection more likely. Prolonged use of hearing aids may also predispose to infection.
  • Most common cause of otitis externa is Pseudomonas Aeruginosa ans Staphylococcus Aureus.
  • External otitis/Diffuse otitis externa is also known as Telephonists ear.
  • Otitis externa haemorrhagica is most commonly caused by influenza virus and is characterised by formation of haemorrhagic bullae on the tympanic membrane.

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