Otitis Externa

Question 1

Define otitis externa

Answer 1

An inflammation of the skin lining the external canal

Question 2

What causes otitis externa?

Answer 2

Most often infection - bacterial or fungal

Can by caused by allergies, irritants or inflammatory conditions - seborrhoeic dermatitis or contact dermatitis

Question 3

What is OE occasionally known as?

Answer 3

Swimmer’s ear

Question 4

What symptoms are associated with otitis externa?

Answer 4

Pain
Itchy ear
Discharge
Hearing loss - from discharge present in the ear canal

Question 5

What signs are found on otoscopy?

Answer 5

Ear canal with erythema, oedema, exudate
Pain on moving tragus or auricle
Pre auricular lymphadenopathy

Question 6

Approximately what percentage of infections are bacterial?

Answer 6

90%

10% are fungal

Question 7

Most cases of bacterial infection involve what bacteria?

Answer 7

Staphylococcus aureus

Pseudomonas aeruginosa

Question 8

What usually causes fungal infection?

Answer 8

Aspergillus species

Candida species

Question 9

What are some risk factors?

Answer 9

Hot and humid climate
Swimming
Older age
Immunocompromised
DM
Narrowed EAM - hereditary or acquired through chronic infection
Insufficient wax - reduced protection
Excessive wax - obstruction, retention of debris
Dermatological conditions - eczema, seborrhoeic dermatitis
Dermatitis affecting canal
Radiotherapy to ear, neck or head

Question 10

What is malignant otitis externa?

Answer 10

A particularly aggressive infection mainly seen in diabetics or immunocompromised patients where the infection spreads from soft tissue of ear canal into the bone
Pseudomonas aeruginosa is causative in 95%

Question 11

How does malignant otitis externa typically present?

Answer 11

Chronic ear discharge despite topical treatment
Deep seated severe ear pain
Cranial nerve palsies (mostly CNVII)

Question 12

How should malignant OE be managed?

Answer 12

Aggressive treatment with IV antibiotics

Plus topical treatment

Question 13

What’s the mortality rate of malignant OE?

Answer 13

10% despite aggressive treatment

Question 14

What is the management for OE?

Answer 14

Analgaesia 
Local heat 
Topical antibiotic or combined topical antibiotic with a steroid for minimum of 7 days, but if symptoms persist continue until resolve (max 14 days) 
If canal debris consider removal 
Ear wick if swollen canal 
Swab discharge in resistant cases

Question 15

When should acetic acid be used?

Answer 15

Mild cases

Question 16

Patients prescribed antibiotic/steroid drops can expect symptoms to last how many days once treatment begun?

Answer 16

6 days

Question 17

When are oral antibiotics indicated?

Answer 17

Systemically unwell
Pre auricular lymphadenopathy
Evidence of spreading infection beyond canal e.g to pinna, neck or face
DM or immunocompromised

Question 18

If systemic antibiotics indicated, what is usually used?

Answer 18

Flucloxacillin - infection usually due to S. aureus
Or clarythromycin if penicillin allergic
7 day course

Question 19

What general advise should be given?

Answer 19

Keep ear dry

Avoid cotton wool to plug discharging ear

Question 20

When is it considered chronic?

Answer 20

Persists for more than 3 months

Question 21

If the tympanic membrane is perforated, what antibiotic class is typically not used?

Answer 21

Aminoglycosides - concerns about ototoxicity

Question 22

What are some differentials?

Answer 22

OM
Perforation
Ramsey Hunt syndrome
Furuncle- infection of hair follicle

Question 23

What is a furuncle?

Answer 23

Small, localised infection with severe pain in ear and local swelling of canal
If lesion bursts there is sudden pain relief

Question 24

If the discharge is thick white/grey with spores, what may this indicate?

Answer 24

Fungal infection

Question 25

What should be done on examination?

Answer 25

Examine ear canal, tympanic membrane, auricle, cervical lymph nodes
Examine surrounding tissue for dermatological conditions

Question 26

Otitis externa can cause significant canal oedema, preventing topical treatment with antibiotic and steroid drops. What should be done in this case?

Answer 26

Referral to ENT - microsuction and insertion of a pope wick needed - to expand the ear canal

Question 27

What should be done in cases of non resolving otitis externa with worsening pain?

Answer 27

Urgent ENT referral - suggests malignant (necrotising) OE

Question 28

What should be done if patient fails to respond to topical antibiotics?

Answer 28

Referral to ENT