Otitis Externa

otitisOuter ear infection or otitis externa is frequently seen in Primary Care. This review of otitis externa on A4Medicine here is to make the reader aware of other conditions which can present similarly- Differential diagnosis and particular focus area on malignant or the necrotizing type ( osteomyelitis of the temporal bone ). Complexity in interpreting ear swab results is discussed. Treatment options are mentioned with a focus on topical treatment.

Inflammatory condition of the ear canal with or without infection Seen in all age group Common presenting complain in UK primary care Peak incidence in one study was in children 7-12 yrs Around 10 % of people will experience at-least one episode in their lifetime Increase in episodes end of summer

It can be difficult to
 distinguish OE from
 otitis media with 
discharge- if canal has discharge
 and swelling 
and TM cannot be seen

Topical antibiotics are
 also Rx of choice
 for AOM with discharge
 and acute typmanostomy
 tube otorrhoea

Predisposing factors –Warm humid climate
 Moisture – macerates the skin of ear canal pH and damages the protective layer of cerumen
○ swimming
○ perspiration
○ high humidity
 Trauma – breach in integrity of canal
○ cotton buds
○ fingernails
○ hearing aids
○ ear plugs
○ paper clips
○ match sticks
○ mechanical wax removal
 Anatomical – narrow hairy ear canal
 Inadequate wax- loss of protective layer or Wax build up
 Chronic dermatological conditions as atopic dermatitis
 Allergic , atopic or irritant dermatitis affecting the ear canal

Causes-Bacterial ( up to 90 % of cases )
○ pseudomonas
○ staph aureus
 Fungal infections
○ over treatment with antibiotics
○ de novo
○ Aspergillus in 90 % cases
○ candida also isolated
 Seborrhoeic dermatitis
 Contact dermatitis can be

○ Allergic or Irritant

Allergic can present as sudden onset , erythematous , itchy , oedeomatous and exudative lesions

○ earrings
○ hearing aid

Presentation-Otalgia Itch Fullness Tinnitus Pain worse when outer ear touched or moved gently or otoscope inserted Ear canal pain when chewing Tender regional lymphadenopathy Jaw pain Hearing loss if the canal very swollen Ear canal or external ear can be red swollen or eczematous Canal edematous and erythematous and may be associated with surrounding cellulitis Discharge may be present Eardrum may be obscured as the ear canal is narrowed or filled with debris Conductive hearing loss

Differential diagnosis –Wax impaction Acute otitis media Otitis media with perforation or ventilation tube present Mastoiditis Foreign body Ear canal trauma Cholesteatoma Malignant or Necrotizing OE Furuncle Ear canal carcinoma Cranial N palsy Wisdom tooth eruption Intracranial abscess Ramsay Hunt syndrome Skull base osteomyelitis Periauricular cyst and fistula Atopic dermatatis Barotrauma Referred pain

Malignant or Necrotizing-Osteomyelitis 
of the Temporal bone Severe headache , fever over 39° or over Intense otalgia that worsens at night Profound hearing loss Temperol mandibular jt pain Trismus Vertigo Facial N palsy ( drooping face side of lesion ) Exposed bone in ear canal Granulation tissue on floor of ear canal It is an invasive infection of cartilage and bone
of the canal and external ear risk factors-Diabetes – present in most cases with malignant otitis Compromised immunity eg
○ chemotherapy
○ CKD Radiotherapy to head or neck Aural irrigation with tap water ( in people with co-existant other risk factors )

Most cases in UK treated in Primary care Only 3 % are referred to secondary care ( Rowlands 2001 ) Mainstay of treatment is
○ pain relief
○ topical medications to control infection and oedema
○ avoidance of contributing factors Patients referred to secondary care usually due to

Common-Antibacterial ear drops used in the UK Aminoglycoside

Neomycin Gentamicin Potentially ototoxic if ear drum perforated Neomycin associated with a 15 % incidence of contact dermatitis Fluoroquinolone
 Ciprofolxacin Ofloxacin Non-ototoxic Twice daily Can be used in people with perforated ear drum Not licensed for use in UK but widely used and deemed acceptable by ENT UK 
( Phillips 2007 ) Topical antibiotics 1st line for diffuse , uncomplicated acute OE No evidence to suggest which product is more effective Prescribe with or without topical steroid for 7-10 days Prescribe a non-ototoxic preparation when the patient has a known or suspected perforation of the TM including a tympanostomy tube Clinical response should be evident within 48-72 hrs but complete recovery can take upto 2 weeks Advice on correct technique of use

Astringent / acidic preparations
○ eg Aluminium acetate 8 % and 13 % ( special order )
○ Acetic acid 2 % spray ( Earcalm® ) can be used in mild cases
Guideline from PHE recommends 2 % acetic spray for 7 days as first line empirical treatment BMJ 2014 in OE Corticosteroids
○ prednisolone sodium phosphate 0.5 %
○ betamethasone sodium phosphate 0.1 % Antibiotics
○ mentioned above and also
Chloramphenicol 5 % drops Antifungal – Clotrimazole 1 % solution Combined preparations
Cilodex® – Dexamethasone 0.1 % and ciprofloxacin 0.3 %
Neomycin various combinations including the popular
Otomize which is Dexamethasone + Glacial acetic acid + Neomycin sulfate

Gentisone HC -gentamicin 0.3 % and 1 % HC
Sofradex® Dex 0.05% + framycetin 0.5% + gramicidin
Corticosteroid and antibiotic/antifungal- Flumetasone pivalate + clioquinol

Follow up-Localized OE f/u is normally not 
required- usually mild and self limiting Consider f/u if 
oral antibiotics prescribed
 Abstain from 
water sports 7-10 days after an acute attack  Most common 
pathogens are 
Pseudomonas aeruginosa & Staphlococcus aureus

Systemic antibiotics-Oral antibiotics are rarely needed. Consider seeking specialist advice if an oral antibiotics is thought to be required

 cellulitis extending beyond the ear canal ear canal occluded by swelling and debris and wick cannot be inserted people with diabetes or compromised immunity and severe infection or high risk of severe infection Use flucloxacillin or clarithromycin if allergic to penicillin for 7 days Consider appropriate f/u

Ear swab-Condition does not improve after initial treatment 
( eg no improvement within 2 weeks of starting top Rx ) OE is recurrent or chronic Topical treatment cannot be delivered After ear surgery Suspicion infection has spread beyond auditory canal Condition severe enough to warrant oral antibiotic use

 Sensitivities are for systemic antibiotics -Not topical administration Much higher conc can be achieved with top antibiotics It is not possible to tell if identified organisms are causing the disease or are merely contaminants Fungal overgrowth can happen following treatment with antibacterial drops

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