• Summary
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• Background
• Clinical Diagnosis
• Investigation
• Treatment
• Non-Antimicrobial Treatment
• Empirical Antimicrobial Treatment
• Directed Antimicrobial Treatment (when microbiology results are known)
• Duration of Treatment
• Switch to oral agent(s)
• Treatment Failure

History
Otitis externa (OE) is an inflammation of the external ear canal presenting with a combination of: otalgia, pruritus and non mucoid ear discharge. Document duration of symptoms (acute OE symptoms <3 weeks, chronic >3 weeks). Document precipitants..

Examination

• Cerumen (wax) or debris that blocks the canal should be removed under direct vision.
• Note appearance of ear canal, any discharge, tympanic membrane (e.g. perforations) and pinna.
• Observe for mastoid cellulitis and palpate mastoid for tenderness.
• Note any cervical lymph node enlargement.
• Carry out cutaneous survey for manifestations of other dermatologic conditions.
• In diabetic or neutropenic children or those with severe pain record cranial nerve function.

Assess severity:

• Mild stage: scant, odourless ear secretion; mild discomfort (not exacerbated by tragal pressure or movement of the pinna) and pruritus; modest erythema; no symptoms of systemic infection.
• Moderate Stage: increasing erythema and oedema; seropurulent ear secretions; pain exacerbated by tragal pressure or movement of the auricle; no symptoms of systemic infection.
• Severe Stage, Extra-canal signs such as auricular cellulitis, canal furuncle or lymphadenopathy OR Systemic symptoms of infection (fevers, chills, vomiting, irritability, poor feeding or general malaise) may be present.
• Necrotising (malignant) otitis externa is likely if pain is severe in relation to clinical findings and/or cranial nerve palsies are present or insulin dependent diabetic (ENT referral required). The condition is very rare in children.

Investigations

• Send ear swab or pus sample for culture only for: treatment failure, chronic otitis externa, necrotising otitis externa and patients who are neutropenic /severely immunosuppressed. For necrotising otitis externa request “topical and systemic susceptibility testing.”
• For necrotising otitis externa: CT temporal bone, arrange for gallium scan and biopsy external ear canal lesions.
• Send Blood Cultures x2 only in patients with symptoms or signs of systemic infection.

Non-Antimicrobial Management
Recommended for all patients with OE:

• Remove/modify precipitating factors
• Remove pus and debris from ear canal (Referral to ENT if this is not possible or the external ear canal is occluded by oedema)
• Analgesia
• A glycerine in ichthammol wick (unlicensed, but extensively used in ENT) should be applied to the ear canal if ≥60% occluded (under direct visualisation, usually by ENT)
• Mild stage disease only – acetic acid spray

Antimicrobial Treatment

Severe stage OE: Systemic and ototopical therapy recommended:
First line ototopical recommended:

• Sofradex (dexamethasone 0.05%, framycetin sulphate 0.5%, gramicidin 0.005%)
  Put two drops into the affected ear(s) 6 hourly for 7 days.

or

• Gentisone HC (Hydrocortisone acetate 1% + Gentamicin 0.3% ear drops) Put two drops into the affected ear(s) 6 hourly for 7 days.

Moderate or severe stage OE: First line ototopical recommended:

• Sofradex (dexamethasone 0.05%, framycetin sulphate 0.5%, gramicidin 0.005%)
  Put two drops into the affected ear(s) 6 hourly for 7 days.

or

• Gentisone HC (Hydrocortisone acetate 1% + Gentamicin 0.3% ear drops)
  Put two drops into the affected ear(s) 6 hourly for 7 days.

N.B For severe stage infection, suspected necrotising otitis externa and if the tympanic membrane is perforated ENT referral is recommended.

1. Systemic antimicrobials:
For severe stage disease with cellulitis of pinna, furuncle formation or necrotising otitis externa.

Table 1. Empirical systemic antimicrobial therapy for acute otitis externa and necrotising otitis externa

#There is some resistance to clarithromycin in Staphylococcus aureus infections. Ensure pre-treatment investigations are performed and monitor for treatment failure.

* Review doses in patients with impaired renal function.

Referral criteria.
Refer to ENT as above, also refer chronic cases (symptoms >3 weeks) to ENT clinic.

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The ear canal is the only skin-lined cul-de-sac in the body. The canal varies in length depending upon the age of the child and is approximately 2.5cm long once fully formed. The medial 2/3 has an osseous support devoid of adnexal structures whereas the lateral 1/3 has a cartilaginous infrastructure covered by a layer of sebaceous and apocrine glands and hair. The glands produce a thin layer of cerumen (wax) that provides protection via a modestly antimicrobial lysozyme and a pH level of 6.9, which discourages microbial growth. The lipid-rich cerumen is also hydrophobic and prevents water from penetrating to the skin and causing maceration. Ear canals self-clean via a lateral epithelial migration towards the external opening, a process that slows with age.

Excessive moisture and trauma, both of which impair the canal’s natural defences, are the two most common precipitants of otitis externa1. Trauma is often caused by the patient when they attempt to “clean” or scratch an itching ear canal with objects such a cotton-buds. Bath or shower water especially if associated with chemicals from shampoos, which can be irritants as well as chlorinated swimming water, can provoke otitis externa.

Otitis externa (OE) is an inflammation of the external ear canal and may be acute lasting less than 3 weeks or progress to a chronic stage lasting months. It is not common in children. Acute OE is typically unilateral and is the result of a bacterial infection in 90% of cases. Symptoms of acute OE include pruritus, pain, and erythema, but as the disease progresses, other problems such as oedema, serous or purulent otorrhoea, and conductive hearing loss may develop. A mucoid discharge suggests discharge from the middle ear via a perforated tympanic membrane. OE commonly occurs as a result of a bacterial infection but fungal or an allergic reaction may also result in the condition1.

Approximately 50% of bacterial cases involve Pseudomonas aeruginosa, followed in incidence by Staphylococcus aureus and then various aerobic and anaerobic bacteria2.

The incidence of fungal infection is only 2%2. The most common pathogen is Aspergillus spp. (80-90% of cases), followed by Candida spp. Classically, fungal infection is the result of prolonged treatment of bacterial OE that alters the flora of the ear canal. Mixed bacterial and fungal infections are thus common.

-Allergic OE results form a contact dermatitis commonly due to a topic agent such as neomycin or a reaction to metals, hearing aid moulds or a variety of cosmetic and cleaning agents³

Box 1 precipitants of otitis externa

Necrotizing otitis externa (Old name – “Malignant otitis externa”)
This is a severe, necrotizing infection that spreads from the skin of the external ear canal to adjacent soft tissues, cartilage and bone. This condition is very rare in children. The condition is not neoplastic. It often involves the adjacent mastoid and should be suspected when canal skin necrosis or granulation appear; the pain is disproportionate to the patients symptoms and cranial nerve palsies especially a facial palsy may occur. The patient is typically poorly controlled insulin diabetic but immunosuppressed children undergoing chemotherapy are also susceptible. Patients should be referred to ENT.

Chronic OE is characterized by pruritus, mild discomfort, and an erythematous external canal that is usually devoid of wax. Again it is not common in children. White keratin debris may fill the ear canal and over time the canal wall skin may become thickened narrowing the external ear canal. A common cause of chronic OE is allergic contact dermatitis from such things as metal earrings, chemicals in cosmetics or shampoos, or the plastic in hearing aids or protection devices. Generalized skin conditions such as atopic dermatitis (i.e., eczema) or psoriasis can also predispose to chronic OE and be difficult to treat in the narrow ear canal. Food sensitivity is also a potential origin of chronic OE associated with atopic dermatitis in up to 48% of patients. A variant of chronic OE is a type IV cell mediated hypersensitivity reaction to components of an ototopical used to treat acute OE4

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Diagnosis of acute OE is made on clinical grounds.

History
The two most characteristic presenting symptoms are otalgia (ear discomfort) and otorrhoea (discharge in or coming from the external auditory canal).

The ear discomfort can range from pruritus to severe pain that is exacerbated by motion of the ear, including chewing. If inflammation causes sufficient swelling to occlude the external auditory canal, the patient may also complain of aural fullness and loss of hearing4. Young children may simply rub or pull at the affected ear.

Evaluate the history for the onset and nature of symptoms; and of prior issues with skin disorders or local trauma, particularly via cotton buds.

The onset of acute OE generally is over a few days to a week.

Examination.
Should include the appearance of the ear canal, any discharge, tympanic membrane, the auricle and mastoid. Cervical lymph nodes should be examined, as well as a cutaneous survey for other dermatologic manifestations. Cerumen or debris that blocks the canal should be removed under direct vision to verify tympanic integrity. In diabetic children, neutropenic or severely immunosuppressed patients and any other patients when necrotising otitis externa is suspected the cranial nerves should be examined and findings recorded; palsies may occur especially facial weakness as necrotising infection spreads along the base of the skull.

The ear canal may contain:

• purulent non mucoid discharge suggestive of acute bacterial infection
• white creamy discharge, suggestive of Candida infection
• cotton wool type mass or hyphae with black spots suggestive of Aspergillus infection
• white keratin mass suggestive of chronic OE

Recommendation: assess severity as below [Evidence level D]:

1. Mild stage: scant, odourless ear secretion; mild discomfort (not exacerbated by tragal pressure or movement of the pinna) and pruritus; modest erythema; no symptoms of systemic infection.
   
   
2. Moderate Stage: increasing erythema and oedema; seropurulent ear secretions; pain exacerbated by tragal pressure or movement of the auricle; No symptoms of systemic infection.
   
   
3. Severe Stage: intense pain, ear canal lumen obstructed and hearing is reduced. Extra-canal signs such as auricular cellulitis or lymphadenopathy may be present. A localised ear canal furuncle may be present. Systemic symptoms of infection (fevers, chills, vomiting, and general malaise) may be present. If patients with local findings suggestive of mild or moderate stage OE have systemic symptoms of infection and no other clinical explanation – treat as severe stage OE.
   
   
4. Necrotising (malignant) otitis externa is likely if pain is severe in relation to clinical findings and/or cranial nerve palsies are present.
   
   N.B Patients with diabetes, neutropenic or severe immunocompromise and those with local circulatory insufficiency (e.g., from irradiation) are prone to rapid escalation from mild to severe manifestations.
   
   Another potential complication of otitis externa is a focal furuncle of the lateral third of the external auditory canal. Typically this starts as a tiny red swelling in the ear canal, later the swelling has a white or yellow centre filled with pus; occasionally this progresses and the swelling eventually completely occludes the ear canal. (see Figure 7)

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Recommendation: In uncomplicated (mild stage) OE no investigations are required. [Evidence level C]:

Recommendation: Ear canal pus samples (ideally) or swabs should be performed in resistant / recurrent cases, or when patients are immunosuppressed or in cases of necrotizing otitis externa.
[Evidence level D]

Recommendation: For necrotising otitis externa: CT temporal bone, arrange gallium scan and biopsy external ear canal lesions.
[Evidence level D]

Recommendation: Blood cultures (2 sets) in patients with systemic signs of infection [Evidence level D]

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Clearance of canal debris is a very important step in managing OE.

• Recommendation: In mild stage cases dry mopping of the external ear canal under direct vision with a cotton bud may suffice (see figure 8). This is usually well tolerated in paediatric cases.[Evidence level C]

• Recommendation: In moderate stage cases debris should be removed with suction under microscopic control. However this requires specialist training and is usually available through the otolaryngology (ENT) department, it may require a general anaesthetic. [Evidence level B]
• Recommendation: Analgesics are appropriate treatment for all stages of OE and can range from non-steroidal anti-inflammatory drugs to mild narcotics as required. [Evidence level A].
• Recommendation: for mild stage disease in children >12 years, 2% acetic acid (Earcalm) (2 sprays 6 hourly until 2 days after symptoms have cleared, but no longer than 7 days) is recommended first line treatment5. [Evidence level B]
• Recommendation: regardless of the ototopical selected, penetration to the canal epithelium is required and any obstruction should be cleared.[Evidence level C]
• Recommendation: If the external canal is narrowed by at least 50% by oedema, placement of a wick ensures ototopical access to the medial canal6. Glycerine in ichthammol wick (unlicensed but extensively used in ENT) is usually applied to the ear canal. The preparation has a significant dehydrating effect and reduces oedema opening up the external canal thereby allowing discharge or infective material6. [Evidence level C]. This will typically require referral to the Otolaryngology department.

Specialist input: Use of POPE wick in conjunction with ototopical medication
In case where the ear canal is narrowed a small sponge can be applied to the external ear canal. This allows the ototopical medication to penetrate deeper into the external ear canal

• When wicks are placed, a return visit in two to three days for removal of the wick is necessary. [Evidence level B]

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There is evidence from a large number of trials including RCT’s that treatments for otitis externa are effective. However, a systematic review of RCTs of topical treatments for acute otitis externa by Rosenfeld in 2006 found that many were of poor quality⁷. There is no good evidence that any one treatment is superior to any other (with the exception of acetic acid alone, which is clearly inferior to other treatments). Evidence is mainly based upon adult studies and extrapolated for the paediatric condition⁸.

1. Topical antimicrobials⁷
Recommendation: First line therapy for otitis externa in children is:

• Sofradex (dexamethasone 0.05%, framycetin sulphate 0.5%, gramicidin 0.005%)
  Put two drops into the affected ear(s) 6 hourly for 7 days.

or

• Gentisone HC (Hydrocortisone acetate 1% + Gentamicin 0.3% ear drops)
  Put drops into the affected ear(s) 6 hourly. Use for a maximum of 7 days. Use alternative if tympanic membrane is perforated
  [Evidence level D]

Recommendation: Alternative topical agents may be used by specialists in selected clinical situations and include:
[Evidence level D]

• Otomize (dexamethasone 0.1%+neomycin 0.5%+acetic acid 2% ear spray)
  Spray once into the affected ear(s) three times a day. Do not use for more than 7 days. Use alternative if tympanic membrane is perforated.
• Locorten-Vioform (flumetasone pivalate 0.02% + clioquinol 1% ear drops)
  Put two drops into the affected ear(s) twice a day for 7 days.
• Polyfax ointment (polymixin B sulphate 10000IU +Bacitracin zinc 500 IU) For use on the outer ear twice a day
• Cilodex (ciprofloxacin 3mg/ml and dexamethasone 1mg/ml)
  Put four drops into the affected ear(s) twice a day for 7 days. Only consider for confirmed Pseudomonas aeruginosa infection AND if perforated tympanic membrane and unresponsive to polyfax.

Evidence review.
Otitis externa warrants the use of an ototopical that includes an antimicrobial agent. There are no randomized controlled trials that directly compare oral with topical antimicrobial therapy, and few that compare different ototopicals. However, the clinical effectiveness of ototopicals, which can achieve local tissue concentrations approximately 1,000 times that of systemic administration, is persuasive, and they have fewer incidents of antibiotic resistance or side effects⁹

In vitro susceptibility testing of antimicrobials to be used topically is not standardised and is of questionable clinical value in management of OE. Causative organisms that are determined to be “resistant” (in vitro) to the topical agent used may still be clinically effective and vice versa. However, this phenomenon may not apply to all antimicrobials and will be affected by the resistance mechanism involved i.e. increasing the concentration of antimicrobials will not overcome some bacterial resistance mechanisms. Consequently, susceptibility testing ear canal isolates will not be undertaken as a matter of routine and if required should be specified on the request form. If systemic antimicrobial therapy is to be used (see below) then antimicrobial susceptibility testing is important and should be specifically requested.

Topical antimicrobials range from aminoglycosides (e.g. neomycin and Gentamicin) and polymyxin to fluoroquinolones, with or without a concomitant steroid. Ototoxicity from aminoglycosides has been associated with open middle ear spaces or prolonged use10 and should be avoided if the eardrum is perforated. Ciprofloxacin resistance is increasing markedly and its reliability as an empirical agent is questionable. Ideally topical ciprofloxacin should be reserved for bacterial otitis externa that is unresponsive to topical aminoglycosides and polymyxin or for use in conjunction with systemic anti-pseudomonal therapy for necrotising otitis externa.

Topical antimicrobials and the perforated (known or suspected) tympanic membrane.
Topical antimicrobials are potentially ototoxic if allowed to penetrate into the middle ear, as in the case of a perforated tympanic membrane or in the presence of a grommet. Topical aminoglycoside antibiotic is contra indicated in such cases, however many specialists do use these drops cautiously in the presence of an infected perforated ear. It is recommended that such drops should only be used after consultation with ENT.

Recommendation: Aminoglycoside are not first choice when the tympanic membrane is perforated, alternatives should be used unless there has been consultation with ENT. [Evidence level D]

A recent literature review concluded that the use of ciprofloxacin 0.3%/dexamethasone 0.1% otic suspension for otitis externa is safe and effective and that dexamethasone improves treatment success in patients with perforated tympanic membranes^{11, 12}

Administration of topical antimicrobials
Patients should be instructed to lie with the affected ear facing up for a few minutes after the administration of eardrops aids migration to the medial canal. Having the patient or someone else “pump the tragus” (push gently down on the tragus several times) improves this process. There is wide variability in the self-administered dosing of ear drops, and relying on another person to place the drops or to perform the pump manoeuvre better standardizes the process.

2. Systemic antimicrobial therapy

Oral antibiotics in conjunction with an ototopical should be considered only when spreading cellulitis or a furuncle is present or in neutropenic/severely immunocompromised patients or for necrotising otitis externa. Antibiotics should be re-evaluated in the light of ear swab results.

Table 1. Empirical systemic antimicrobial therapy for acute otitis externa and necrotising otitis externa

* Review doses in patients with impaired renal function.
#There is some resistance to clarithromycin in Staphylococcus aureus infections. Ensure pre-treatment investigations are performed and monitor for treatment failure.

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When culture results are known, it may be necessary to amend antimicrobial therapy. Discuss with microbiology if required. Recommendations below are for patients requiring systemic antimicrobial therapy:

Bacterial otitis externa
Confirmed Staphylococcus aureus (meticillin susceptible) infection should be treated with Flucloxacillin , doses as in table 1.

Confirmed Staphylococcus aureus (meticillin resistant, MRSA) infection should be treated with Vancomycin , (15mg/kg 8-hourly and the dose is adjusted according to blood levels.) Trough levels are taken before every third dose.
If the isolate is susceptible, clarithromycin is an alternative. No real evidence based guidelines for any systemic treatment of OE. For oral switch clarithromycin is appropriate if the isolate is susceptible, otherwise discuss with microbiology.

Confirmed Streptococcus pyogenes (group A Streptococcus) infection should be treated with benzylpenicillin 1.2g 4 hourly IV or, in a patient with genuine penicillin allergy Vancomycin , doses as in table 1.

Confirmed Pseudomonas aeruginosa infection – discuss with microbiology

Other bacterial pathogens - discuss with microbiology.

Fungal otitis externa
Fungal infection accounts for approximately 2% of acute OE. Most fungal infections are mild and can be treated with a 2% acetic acid and cleaning of the outer ear canal. [Evidence Level C].

More established disease requires topical antifungal agents. Removing fungal debris from the external ear canal under direct vision is an important part in management. [Evidence Level D].

Antifungal Ototopicals:

• Canesten (clotrimazole)

Put two drops into the affected ear(s) 3 times a day and continue for 14 days following resolution of symptoms.

• Locorten-Vioform (flumetasone pivalate 0.02% + clioquinol 1% ear drops)

Put two drops into the affected ear(s) twice a day for 14 days.

• Otocomb otic (triamcinolone acetonide 1 mg, neomycin (as sulfate) 2.5 mg, gramicidin 0.25 mg and nystatin 100,000 IU in a proprietary mixture of polyethylene and liquid paraffin (Plastibase)

Apply to the affected ear(s) twice a day for one week

• Lamisil (terbinafine 1% cream)

Apply to the affected ear(s) twice a day for two weeks. This is best applied under direct microscopic vision and typically requires referral to ENT

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Ototopic therapy usually should continue for 7 days in bacterial infections⁵. [Evidence level C]

Fungal otitis externa -therapy for 14 days following resolution of symptoms. [Evidence level C]

Necrotising otitis externa usually involves bony infection and requires a minimum of 6 weeks of therapy [Evidence level C]

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See Table 1 for oral switch guidance

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Considerations when otitis externa fails to respond to initial therapy:

1. Contact dermatitis (original issue or reaction to ototopical).
   • Neomycin sensitivity occurs in 5 to 18% of patients.
   • Also the preservatives benzalkonium chloride, thimerosal, and propylene glycol can incite local sensitization. Stop ototopical and observe.
2. Failure to adhere to preventive measures.
   (e.g., temporary cessation of swimming or hearing aid usage). Reiterate preventive measures, explore reasons for non-concordance.
3. Faulty or infrequent administration of ototopical. Observe administration method and educate if required.
4. Inadequate penetration of ototopical because of canal debris or narrowing. Clean ear canal and recommence topical therapy.
5. Ototopical not effective against bacteria or fungi involved (or it is a mixed bacterial and fungal problem). Stop ineffective ototopical, sends ear swab for culture and review with results.
6. Neutropenia/severe immunosuppression. Review ear swab results and discuss with microbiology (may require prolonged therapy and possibly oral antimicrobials).
7. Necrotising (malignant) otitis externa. This may require intravenous antimicrobials and surgical debridement; refer to ENT and discuss with microbiology.
8. Misdiagnosis, including dermatologic conditions (e.g., Cancer, systemic psoriasis, seborrhoea, dermatophytid reaction). Refer to ENT.

Chronic otitis externa not responding to ototopicals
In case of otitis externa resistant to the above topical drops Otocomb otic can be used. [Evidence Level D]. This is widely used in ENT departments and while little published data exists it appears to be highly effective. The cream can be applied topically twice daily to the ear for one week or used to fill the external ear canal.

• Otocomb otic (triamcinolone acetonide 1 mg, neomycin (as sulfate) 2.5 mg, gramicidin 0.25 mg and nystatin 100,000 IU in a proprietary mixture of polyethylene and liquid paraffin (Plastibase))

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