Overview
Otitis Externa
Quick Reference
Critical Alerts
- Necrotizing (malignant) otitis externa is life-threatening: Diabetics, immunocompromised; skull base osteomyelitis
- Differentiate from otitis media: OE = canal involvement, pain with tragal pressure; OM = middle ear, TM abnormality
- Topical antibiotics are first-line: Not systemic
- Keep ear dry during treatment
- Refer for persistent or severe cases: ENT for debridement
Key Diagnostics
| Finding | Otitis Externa | Otitis Media |
|---|---|---|
| Pain with tragal pressure | Yes | No |
| Canal erythema/edema | Yes | No |
| Tympanic membrane | Normal or obscured | Bulging, erythematous |
| Discharge | From canal | From middle ear (if TM perforated) |
Emergency Treatments
| Condition | Treatment |
|---|---|
| Uncomplicated OE | Topical fluoroquinolone drops (ofloxacin, ciprofloxacin/dexamethasone) × 7-10 days |
| Severe canal edema | Ear wick + topical drops |
| Necrotizing OE | IV antipseudomonal antibiotics + CT + ENT |
| Pain control | NSAIDs, acetaminophen |
Definition
Overview
Otitis externa (OE), also known as "swimmer's ear," is an infection of the external auditory canal. It is typically caused by bacteria (Pseudomonas aeruginosa, Staphylococcus aureus) and presents with ear pain, itching, and discharge. Topical antibiotic drops are the mainstay of treatment. Necrotizing (malignant) otitis externa is a severe form seen in diabetics and immunocompromised patients.
Classification
By Severity:
| Type | Features |
|---|---|
| Mild | Minimal canal edema, mild discomfort |
| Moderate | Canal partially occluded, moderate pain |
| Severe | Canal fully occluded, severe pain, may extend beyond canal |
By Chronicity:
| Type | Duration |
|---|---|
| Acute | <6 weeks |
| Chronic | > months |
Special Type:
| Type | Features |
|---|---|
| Necrotizing (malignant) OE | Osteomyelitis of skull base; diabetics, immunocompromised |
Epidemiology
- Common: 10% of people affected at some point
- Peak age: 7-12 years; also common in adults
- Risk increases with: Swimming, humid climates, hearing aid use
Etiology
Pathogens:
| Organism | Frequency |
|---|---|
| Pseudomonas aeruginosa | 40-50% |
| Staphylococcus aureus | 20-30% |
| Other Gram-negatives | 10% |
| Fungi (Aspergillus, Candida) | 5-10% (otomycosis) |
Risk Factors:
| Factor | Mechanism |
|---|---|
| Swimming | Moisture, pH change |
| Ear instrumentation (Q-tips) | Trauma, cerumen removal |
| Hearing aids/Ear plugs | Occlusion, moisture |
| Eczema, psoriasis | Compromised skin barrier |
| Diabetes, immunocompromise | Risk of necrotizing OE |
Pathophysiology
Mechanism
- Disruption of protective cerumen: Caused by water, trauma, or instrumentation
- Moisture and pH change: Favor bacterial growth
- Bacterial colonization: Pseudomonas, Staph
- Inflammation: Edema, erythema, pain
- Extension (in severe cases): Cellulitis, perichondritis, necrotizing OE
Necrotizing Otitis Externa
- Invasive infection extending to skull base
- Osteomyelitis of temporal bone
- Can involve cranial nerves (VII most common)
- Life-threatening if untreated
Clinical Presentation
Symptoms
| Symptom | Description |
|---|---|
| Ear pain (otalgia) | Often severe; worse with jaw movement |
| Itching | Early symptom |
| Discharge | Often purulent |
| Hearing loss | If canal occluded |
| Fullness | Sensation of blockage |
History
Key Questions:
Physical Examination
External Ear:
| Finding | Significance |
|---|---|
| Pain with tragal pressure | Classic for OE; not present in OM |
| Pain with pinna manipulation | Classic for OE |
| Canal erythema and edema | Hallmark |
| Purulent discharge | Infection |
| Debris in canal | Fungal or severe bacterial |
| Periauricular cellulitis | Severe OE |
| Granulation tissue in canal | Necrotizing OE |
Tympanic Membrane:
Cranial Nerve Exam:
Ear pain, discharge, itching?
Common presentation.
Recent swimming or water exposure?
Common presentation.
Ear instrumentation (Q-tips)?
Common presentation.
Hearing aid use?
Common presentation.
Diabetes or immunocompromise?
Common presentation.
Prior ear infections or surgery?
Common presentation.
Duration of symptoms?
Common presentation.
Red Flags
Necrotizing (Malignant) Otitis Externa
| Finding | Action |
|---|---|
| Diabetes or immunocompromise + severe OE | High suspicion |
| Granulation tissue at bone-cartilage junction | Pathognomonic |
| Facial nerve palsy (CN VII) | Indicates skull base involvement |
| Cranial nerve deficits (IX, X, XI, XII) | Advanced disease |
| Fever, severe pain, refractory to topical treatment | CT, MRI |
Other Concerning Features
| Finding | Concern |
|---|---|
| Periauricular cellulitis | Extension of infection |
| Perichondritis | Auricular cartilage involvement |
| Mastoid tenderness | Mastoiditis |
Differential Diagnosis
Other Causes of Ear Pain
| Diagnosis | Features |
|---|---|
| Acute otitis media | Bulging TM, fever, middle ear effusion |
| Foreign body | Visible on otoscopy |
| Cerumen impaction | Impacted wax, hearing loss |
| Herpes zoster oticus (Ramsay Hunt) | Vesicles in canal, facial palsy |
| Contact dermatitis | Itching, history of earring/product use |
| Furunculosis | Localized abscess in canal |
| Referred pain (TMJ, dental) | Normal ear exam |
Diagnostic Approach
Clinical Diagnosis
- OE is a clinical diagnosis
- Based on history and otoscopy
Otoscopy
| Finding | Significance |
|---|---|
| Canal erythema, edema | Hallmark |
| Discharge | Bacterial or fungal |
| TM normal (if visible) | Differentiates from OM |
| Granulation tissue | Necrotizing OE |
Imaging
Not Routinely Needed
Indications for CT/MRI Temporal Bone:
| Indication | Imaging |
|---|---|
| Suspected necrotizing OE | CT with contrast |
| Cranial nerve involvement | MRI |
| Refractory to treatment | CT |
Laboratory
| Test | Indication |
|---|---|
| Ear culture | Refractory cases, immunocompromised |
| ESR, CRP | Necrotizing OE |
| Glucose | Undiagnosed diabetes |
Treatment
Principles
- Topical antibiotics are first-line: Not systemic
- Keep ear dry: Avoid water during treatment
- Pain control: NSAIDs, acetaminophen
- Ear wick if canal occluded: To deliver drops
- ENT referral for severe or necrotizing OE
Topical Antibiotic Drops
First-Line:
| Agent | Dose | Duration |
|---|---|---|
| Ofloxacin otic 0.3% | 5-10 drops BID | 7-10 days |
| Ciprofloxacin/Dexamethasone (Ciprodex) | 4 drops BID | 7 days |
| Ciprofloxacin otic 0.3% | 3-4 drops BID | 7 days |
Alternative (If Fungal Suspected):
| Agent | Dose |
|---|---|
| Clotrimazole 1% solution | Apply BID × 10-14 days |
| Acetic acid otic (VoSol) | Acidifies canal |
Notes:
- Fluoroquinolones are safe if TM perforated
- Aminoglycoside-containing drops (neomycin) are ototoxic if TM perforated—avoid
Ear Wick
Indication: Canal too edematous to allow drop penetration
Technique:
- Insert wick gently into canal
- Apply drops to wick; wick swells and delivers medication
- Remove or replace in 24-48 hours
Pain Control
| Agent | Dose |
|---|---|
| Ibuprofen | 400-600 mg q6-8h |
| Acetaminophen | 650-1000 mg q6h |
| Opioids (short-term) | For severe pain |
Necrotizing Otitis Externa
| Intervention | Details |
|---|---|
| CT temporal bone | Assess bone involvement |
| MRI | If cranial nerve involvement |
| IV antipseudomonal antibiotics | Ciprofloxacin IV, pip-tazo, cefepime |
| ENT consultation | Urgent |
| Surgical debridement | If necrotic tissue |
| Hyperbaric oxygen | Adjunct in refractory cases |
| Long duration of therapy | 6-8 weeks |
Disposition
Discharge Criteria
- Uncomplicated OE
- Pain controlled
- Able to administer drops
- No signs of necrotizing OE
Admission Criteria
- Necrotizing OE
- Severe cellulitis
- Immunocompromised with severe infection
- Unable to tolerate oral intake
Referral
| Indication | Referral |
|---|---|
| Suspected necrotizing OE | ENT (urgent) |
| Refractory to treatment | ENT |
| Severe canal edema requiring debridement | ENT |
Follow-Up
| Situation | Follow-Up |
|---|---|
| Uncomplicated OE | PCP in 1-2 weeks if not improving |
| Wick placed | 24-48 hours for wick removal/replacement |
| Necrotizing OE | ENT and infectious disease |
Patient Education
Condition Explanation
- "You have an infection of the ear canal, often called swimmer's ear."
- "Antibiotic ear drops will treat the infection."
- "Keep your ear dry during treatment."
Home Care
- Apply ear drops as directed
- Keep ear dry (use cotton ball with petroleum jelly when showering)
- Avoid swimming until healed
- Do not use Q-tips or other objects in ear
Warning Signs to Return
- Pain getting worse despite treatment
- Fever
- Facial weakness or drooping
- Swelling or redness spreading around ear
- No improvement after 48-72 hours
Special Populations
Diabetics
- Higher risk of necrotizing OE
- Maintain tight glucose control
- Low threshold for imaging and ENT referral
Immunocompromised
- Higher risk of severe and necrotizing OE
- Broader antibiotic coverage
- ENT involvement early
Perforated Tympanic Membrane
- Avoid aminoglycoside-containing drops (ototoxic)
- Fluoroquinolone drops are safe
Fungal Otitis Externa (Otomycosis)
- More common in humid climates, after antibiotic use
- Debris may appear fluffy or black
- Treat with antifungal drops (clotrimazole)
Quality Metrics
Performance Indicators
| Metric | Target | Rationale |
|---|---|---|
| Topical (not systemic) abx for uncomplicated OE | >0% | Guideline adherence |
| Tragal and pinna tenderness documented | >0% | Diagnostic |
| Necrotizing OE identified and referred | 100% | Life-threatening |
| TM status documented | 100% | Differentiate from OM |
Documentation Requirements
- Canal and TM appearance
- Tragal/pinna tenderness
- Risk factors (diabetes, immunocompromise)
- Treatment prescribed
- Return precautions
Key Clinical Pearls
Diagnostic Pearls
- Tragal pressure pain = OE: Not OM
- TM normal in OE: If visible
- Granulation tissue = Necrotizing OE: CT, ENT
- Diabetes + severe OE = High suspicion for necrotizing OE
- Fungal OE (otomycosis): Fluffy debris, pruritus
- Check CN VII if necrotizing OE suspected
Treatment Pearls
- Topical drops are first-line: Not oral antibiotics
- Fluoroquinolone drops are safe with TM perforation: Aminoglycosides are not
- Wick for occluded canal: Delivers drops to canal
- Keep ear dry: No swimming, use barriers when showering
- Acetic acid drops help prevent recurrence: Acidifies canal
- Necrotizing OE needs IV antibiotics and ENT
Disposition Pearls
- Most uncomplicated OE can be discharged: With topical drops
- Admit for necrotizing OE: High mortality if untreated
- ENT for refractory or severe cases: Debridement may be needed
- Follow-up if not improving in 48-72 hours
References
- Rosenfeld RM, et al. Clinical Practice Guideline: Acute Otitis Externa. Otolaryngol Head Neck Surg. 2014;150(1 Suppl):S1-S24.
- Kaushik V, et al. Interventions for acute otitis externa. Cochrane Database Syst Rev. 2010;(1):CD004740.
- Roland PS, et al. Acute otitis externa: Clinical practice guideline. 2006.
- Carfrae MJ, Kesser BW. Malignant otitis externa. Otolaryngol Clin North Am. 2008;41(3):537-549.
- Rubin Grandis J, et al. The changing face of malignant (necrotising) external otitis. Lancet Infect Dis. 2004;4(1):34-39.
- Hajjartabar M. Poor diabetic control as a risk factor for necrotizing otitis externa. J Laryngol Otol. 1999;113(11):1047-1049.
- Schaefer P, et al. Acute otitis externa: an update. Am Fam Physician. 2012;86(11):1055-1061.
- UpToDate. Acute otitis externa: clinical features and diagnosis. 2024.