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Otitis Externa
Douglas S. Parks, MD
image BASICS
DESCRIPTION
Inflammation of the external auditory canal:
  • Acute diffuse otitis externa: the most common form; an infectious process, usually bacterial, occasionally fungal (10%)
  • Acute circumscribed otitis externa: synonymous with furuncle; associated with infection of the hair follicle, a superficial cellulitic form of otitis externa
  • Chronic otitis externa: same as acute diffuse but of longer duration (>6 weeks)
  • Eczematous otitis externa: may accompany typical atopic eczema or other primary skin conditions
  • Necrotizing malignant otitis externa: an infection that extends into the deeper tissues adjacent to the canal; may include osteomyelitis and cellulitis; rare in children
  • System(s) affected: skin/exocrine
  • Synonym(s): swimmer's ear
EPIDEMIOLOGY
Incidence
  • Unknown; higher in the summer months and in warm, wet climates
  • Predominant age: all ages
  • Predominant sex: male = female
Prevalence
  • Acute, chronic, and eczematous: common
  • Necrotizing: uncommon
ETIOLOGY AND PATHOPHYSIOLOGY
  • Acute diffuse otitis externa
    • Traumatized external canal (e.g., from use of cotton swab)
    • Bacterial infection (90%): Pseudomonas (67%), Staphylococcus, Streptococcus, gram-negative rods
    • Fungal infection (10%): Aspergillus (90%), Candida, Phycomycetes, Rhizopus, Actinomyces, Penicillium
  • Chronic otitis externa: bacterial infection: Pseudomonas
  • Eczematous otitis externa (associated with primary skin disorder)
    • Eczema
    • Seborrhea
    • Psoriasis
    • Neurodermatitis
    • Contact dermatitis
    • Purulent otitis media
    • Sensitivity to topical medications
  • Necrotizing otitis externa
    • Invasive bacterial infection: Pseudomonas, increasing incidence of methicillin-resistant Staphylococcus aureus (MRSA)
    • Associated with immunosuppression
RISK FACTORS
  • Acute and chronic otitis externa
    • Traumatization of external canal
    • Swimming
    • Hot, humid weather
    • Hearing aid use
  • Eczematous: primary skin disorder
  • Necrotizing otitis externa in adults
    • Advanced age
    • Diabetes mellitus (DM)
    • Debilitating disease
    • AIDS
    • Immunosuppression
  • Necrotizing otitis externa in children (rare)
    • Leukopenia
    • Malnutrition
    • DM
    • Diabetes insipidus
GENERAL PREVENTION
  • Avoid prolonged exposure to moisture.
  • Use preventive antiseptics (acidifying solutions with 2% acetic acid [white vinegar] diluted 50/50 with water or isopropyl alcohol, or 2% acetic acid with aluminum acetate [less irritating]) after swimming and bathing.
  • Treat predisposing skin conditions.
  • Eliminate self-inflicted trauma to canal with cotton swabs and other foreign objects.
  • Diagnose and treat underlying systemic conditions.
  • Use ear plugs when swimming.
image DIAGNOSIS
PHYSICAL EXAM
  • Ear canal: red, containing purulent discharge and debris
  • Pain on manipulation of the pinnae
  • Possible periauricular adenitis
  • Possible eczema of pinna
  • Cranial nerve (VII, IX to XII) involvement (extremely rare)
DIFFERENTIAL DIAGNOSIS
  • Idiopathic ear pain
  • Otitis media with perforation
  • Hearing loss
  • Cranial nerve (VII, IX to XII) palsy with necrotizing otitis externa
  • Wisdom tooth eruption
  • Basal cell or squamous cell carcinoma
DIAGNOSTIC TESTS & INTERPRETATION
  • Gram stain and culture of canal discharge (occasionally helpful)
  • Antibiotic pretreatment may affect results.
  • Radiologic evaluation of deep tissues in necrotizing otitis externa with high-resolution CT scan, MRI, gallium scan, and bone scan
Test Interpretation
  • Acute and chronic otitis externa: desquamation of superficial epithelium of external canal with infection
  • Eczematous otitis externa: pathologic findings consistent with primary skin disorder; secondary infection on occasion
  • Necrotizing otitis externa: vasculitis, thrombosis, and necrosis of involved tissues; osteomyelitis
image TREATMENT
Outpatient treatment, except for resistant cases and necrotizing otitis externa
GENERAL MEASURES
  • Cleaning the external canal may facilitate recovery.
  • Analgesics as appropriate for pain
  • Antipruritic and antihistamines (eczematous form)
  • Ear wick (Pope) for nearly occluded ear canal
MEDICATION
  • Resistance is an increasing problem. Pseudomonas is the most common bacteria, and it is more susceptible to fluoroquinolones such as ciprofloxacin or ofloxacin, whereas Staphylococcus is equally susceptible to both fluoroquinolones and polymyxin B combinations (1)[B]. If a patient has recurring episodes or is not improved in 2 weeks, change the class of antibacterial and consider cultures and sensitivities.
  • There is evidence that using a topical antibiotic with a corticosteroid shortens time to symptom resolution, although there is no evidence that it increases overall cure rate. There is not enough evidence to demonstrate that any antibiotic regimen is clearly superior to any other (2)[B].
  • Oral antibiotics are indicated only if there is associated otitis media. Oral antibiotics alone are not effective and markedly increase the risk of progressing to chronic otitis externa.
  • Analgesics as needed; narcotics may be necessary. Recurrent otitis externa may be prevented by applying equal parts white vinegar and isopropyl alcohol (over-the-counter [OTC] rubbing alcohol) to external auditory canals after bathing and swimming.
P.741

First Line
  • Acute bacterial and chronic otitis externa
    • Ciprofloxacin 0.3% and dexamethasone 0.1% suspension: 4 drops BID for 7 days or ofloxacin: 0.3% solution 10 drops once a day for 7 days (3)[A]. Less ototoxicity and reported antibiotic resistance (4)[A], but branded drugs are far more expensive.
    • Neomycin/polymyxin B/hydrocortisone (Cortisporin): 5 drops QID. If the tympanic membrane is ruptured, use the suspension; otherwise, the solution may be used; may be ototoxic and resistance-developing in Staphylococcus and Streptococcus sp. (5)[B]; least expensive.
    • Acetic acid 2% with hydrocortisone 1%: 3 to 5 drops q4-6h for 7 days; may cause minor local stinging. This is as effective as neomycin-polymyxin B (6)[B] but is expensive. It may take up to 2 days longer to achieve resolution of symptoms (2)[A]. A wick may be helpful in severe cases by keeping the canal open and keeping antibiotic solution in contact with infected skin (7)[C].
  • Fungal otitis externa
    • Topical therapy, antiyeast for Candida or yeast: 2% acetic acid 3 to 4 drops QID; clotrimazole 1% solution; itraconazole oral
    • Parenteral antifungal therapy: amphotericin B
    • Patients with Ramsay-Hunt syndrome: acyclovir IV
  • Eczematous otitis externa: topical therapy
    • Acetic acid 2% in aluminum acetate
    • Aluminum acetate (5%; Burow solution)
    • Steroid cream, lotion, ointment (e.g., triamcinolone 0.1% solution)
    • Antibacterial, if superinfected
  • Necrotizing otitis externa
    • Parenteral antibiotics: antistaphylococcal and antipseudomonal
    • 4 to 6 weeks of therapy
    • Fluoroquinolones PO for 2 to 4 weeks
Second Line
  • Acute bacterial and chronic otitis externa
    • Betamethasone 0.05% solution may be as effective as a polymyxin B combination without the risk of ototoxicity or antibiotic resistance. However, the data are not very robust, and more study is needed (2)[A].
  • Azole antifungals for fungal otitis externa
ISSUES FOR REFERRAL
Resistant cases or those requiring surgical intervention
SURGERY/OTHER PROCEDURES
For necrotizing otitis externa or furuncle
COMPLEMENTARY & ALTERNATIVE MEDICINE
  • OTC white vinegar; 3 drops in affected ear for minor case
  • Tea tree oil in various concentrations has been used as an antiseptic (8)[B]. Ototoxicity has been reported in animal studies at very high doses.
  • Grapefruit seed extract in various concentrations has been described as useful in the lay literature.
INPATIENT CONSIDERATIONS
Admission Criteria/Initial Stabilization
Necrotizing otitis media requiring parenteral antipseudomonal antibiotics
Discharge Criteria
Resolution of infection
image ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
No restrictions
Patient Monitoring
  • Acute otitis externa
    • 48 hours after therapy instituted to assess improvement
    • At the end of treatment
  • Chronic otitis externa
    • Every 2 to 3 weeks for repeated cleansing of canal
    • May require alterations in topical medication, including antibiotics and steroids
  • Necrotizing otitis externa
    • Daily monitoring in hospital for extension of infection
    • Baseline auditory and vestibular testing at beginning and end of therapy
DIET
No restrictions
PROGNOSIS
  • Acute otitis externa: rapid response to therapy with total resolution
  • Chronic otitis externa: With repeated cleansing and antibiotic therapy, most cases will resolve. Occasionally, surgical intervention is required for resistant cases.
  • Eczematous otitis externa: Resolution will occur with control of the primary skin condition.
  • Necrotizing otitis externa: usually can be managed with débridement and antipseudomonal antibiotics; recurrence rate is 100% when treatment is inadequate. Surgical intervention may be necessary in resistant cases or if there is cranial nerve involvement. Mortality rate is significant, probably secondary to the underlying disease.
REFERENCES
1. Dohar JE, Roland P, Wall GM, et al. Differences in bacteriologic treatment failures in acute otitis externa between ciprofloxacin/dexamethasone and neomycin/polymyxin B/hydrocortisone: results of a combined analysis. Curr Med Res Opin. 2009;25(2):287-291.
2. Rosenfeld RM, Schwartz SP, Cannon CR, et al. Clinical practice guideline: acute otitis externa. Otolaryngol Head Neck Surg. 2014;150(1 Suppl);S1-S24.
3. Kaushik V, Malik T, Saeed SR. Interventions for acute otitis externa. Cochrane Database Syst Rev. 2010;(1):CD004740.
4. Mösges R, Nematian-Samani M, Hellmich M, et al. A meta-analysis of the efficacy of quinolone containing otics in comparison to antibiotic-steroid combination drugs in the local treatment of otitis externa. Curr Med Res Opin. 2011;27(10):2053-2060.
5. Cantrell HF, Lombardy EE, Duncanson FP, et al. Declining susceptibility to neomycin and polymyxin B of pathogens recovered in otitis externa clinical trials. South Med J. 2004;97(5):465-471.
6. van Balen FA, Smit WM, Zuithoff NP, et al. Clinical efficacy of three common treatments in acute otitis externa in primary care: randomised controlled trial. BMJ. 2003;327(7425):1201-1205.
7. Block SL. Otitis externa: providing relief while avoiding complications. J Fam Pract. 2005;54(8):669-676.
8. Farnan TB, McCallum J, Awa A, et al. Tea tree oil: in vitro efficacy in otitis externa. J Laryngol Otol. 2005;119(3):198-201.
See Also
&NA;
Algorithm: Ear Pain
Codes
&NA;
ICD10
  • H60.90 Unspecified otitis externa, unspecified ear
  • H60.339 Swimmer's ear, unspecified ear
  • H60.509 Unsp acute noninfective otitis externa, unspecified ear
Clinical Pearls
&NA;
  • Acute diffuse otitis externa is the most common form: bacterial (90%), occasionally fungal (10%).
  • Acute circumscribed otitis externa is associated with infection of a hair follicle.
  • Chronic otitis externa is the same as acute diffuse but of longer duration (>6 weeks).
  • Eczematous otitis externa may accompany typical atopic eczema or other primary skin conditions.
  • Necrotizing malignant otitis externa is an infection that extends into the deeper tissues adjacent to the canal. It may include osteomyelitis and cellulitis; it is rare in children.