Otitis Externa
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Direct answer
Pain on pulling the pinna or pressing the tragua is the signature of otitis externa — infection of the ear canal skin — and it separates the condition from middle-ear disease at the first touch. The diffuse form, "swimmer's ear", is usually Pseudomonas aeruginosa, treated with meticulous aural toilet and topical quinolone-steroid drops with strict dryness. Two Indian exam favourites live alongside it: otomycosis, the tropical fungal canal infection whose black "wet newspaper" specks identify Aspergillus niger; and malignant (necrotising) otitis externa, the elderly diabetic's Pseudomonas invasion of the skull base, diagnosed by granulation at the bony-cartilaginous junction and treated with prolonged systemic ciprofloxacin.
What you must remember
- Diagnostic sign: tragal tenderness and pain on pulling the pinna distinguish canal disease from otitis media, where the pinna and tragus are comfortable.
- Diffuse bacterial otitis externa: water exposure (swimming), local trauma from matches, pins and cotton buds — still common habits — hearing aids and humid weather; Pseudomonas aeruginosa and Staphylococcus aureus lead.
- Treatment: dry mopping or suction clearance of debris, topical ciprofloxacin with steroid drops for 7–10 days, analgesia, and strict water prevention with cotton-wool and petroleum jelly during baths.
- Otomycosis, frequent in tropical India: intense itching with watery discharge; Aspergillus niger gives black peppered "wet newspaper" debris, Candida a creamy curd; treatment is meticulous suction toileting with topical clotrimazole or acetic acid, and dryness — drops alone fail on loaded debris.
- Furuncle of the canal: Staphylococcus aureus abscess of a hair follicle — and follicles exist only in the cartilaginous outer third, so a furuncle never arises from the bony canal: a viva rule quoted for decades.
- Malignant otitis externa: elderly diabetic or immunosuppressed patient, agonising otalgia, purulent discharge, granulation tissue on the floor of the canal at the bony-cartilaginous junction, raised ESR, often cranial nerve palsies (VII first); Pseudomonas confirmed on culture.
- Malignant OE management: prolonged oral ciprofloxacin for six weeks or more (active against Pseudomonas), aggressive glycaemic control, local debridement, imaging with CT and MRI or bone scan for osteomyelitis extent; aminoglycoside drops are avoided with a perforated drum.
The diabetic ear, walked through
An 68-year-old man with long-standing type 2 diabetes presents with three weeks of severe right ear pain unrelieved by two courses of oral antibiotics, scanty discharge and now a drooping right corner of the mouth. The pain is out of proportion: worse at night, deep and boring. Examination shows tender canal skin, debris, and — the decisive finding — a pad of granulation on the floor of the canal at the bony-cartilaginous junction. Swab grows Pseudomonas aeruginosa; ESR is markedly elevated; the facial nerve is already involved. This is malignant otitis externa progressing to skull-base osteomyelitis, and underdiagnosing it as "resistant swimmer's ear" costs the patient his cranial nerves or life.
The pathway is then fixed. Image with contrast CT of the temporal bone for bone destruction and MRI or nuclear scans for soft-tissue and osteomyelitis extent. Start prolonged oral ciprofloxacin (with its Pseudomonas cover and bone penetration) for six to eight weeks, guided by cultures; bring the diabetes under control; debride canal granulations; and monitor ESR serially as the treatment meter. The facial palsy, present at diagnosis, is treated with eye protection while recovery is awaited. Contrast this with the same patient's neighbour on the ward — a young swimmer with a painful, itchy, debris-filled canal and a black-speckled discharge: suction toileting under microscope vision reveals the wet-newspaper appearance of Aspergillus, cured by cleaning plus clotrimazole drops and keeping the canal dry.
How the exam frames it
Stems turn on three discriminators. Pain on touching the pinna answers otitis externa, not media. Black specks with itching in a tropical patient answer otomycosis with Aspergillus niger and clotrimazole. The elderly diabetic with severe pain and canal granulation answers malignant otitis externa: organism Pseudomonas, drug ciprofloxacin six weeks or more, and the bony-cartilaginous junction as the site of granulation — a site-specific one-liner repeated across years of papers. The furuncle question is the anatomical zinger: follicles only in the outer cartilaginous third.
Frequently asked questions
Which organism most commonly causes diffuse bacterial otitis externa?
Pseudomonas aeruginosa, followed by Staphylococcus aureus; treatment is aural toilet with topical quinolone-steroid drops.
How does otomycosis present and how is it treated?
Intense itching with watery discharge and black "wet newspaper" debris of Aspergillus niger (or creamy curds of Candida); treated by suction toileting and topical clotrimazole or acetic acid with strict dryness.
Why does a furuncle occur only in the outer third of the canal?
Hair follicles and sebaceous glands exist only in the cartilaginous outer third; the bony medial canal has thin skin without adnexae.
What defines malignant otitis externa?
A Pseudomonas skull-base infection of elderly diabetics: agonising otalgia, granulation on the canal floor at the bony-cartilaginous junction, raised ESR, and cranial nerve involvement.
How is malignant otitis externa treated?
Prolonged oral ciprofloxacin for six weeks or more with strict glycaemic control, local debridement, imaging follow-up, and monitoring of ESR; hyperbaric oxygen is an adjunct in refractory disease.