ENTPending review

Otitis externa

Inflammation of the skin lining the ear canal, usually triggered by moisture or trauma disrupting its protective acid mantle, treated topically because the problem is a superficial skin infection rather than a deep-seated one.

In a nutshell

Moisture or trauma strips the ear canal's protective acid mantle, letting bacteria or fungi overgrow inflamed canal skin. Because disease is confined to the skin, topical treatment works; but in diabetic or immunosuppressed patients the same organisms can invade bone at the skull base as malignant otitis externa.

Classic presentation

Ear pain, itch and discharge after swimming or canal trauma, with a red, swollen ear canal and pain markedly worse on moving the tragus or pinna.

Key points

The canal's protective acid mantle and cerumen are disrupted by water, trauma or skin disease, allowing Pseudomonas, Staphylococcus or fungi to overgrow.

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Educational content pending clinical review. Not medical advice.