Otitis externa

Otitis externa (OE) is an inflammation of the external auditory canal (EAC) and is most often the result of a local bacterial infection. Risk factors for OE include exposure to water and injury to the skin of the EAC. OE is characterized by ear pain, fullness, and/or itching, and tenderness of the tragus and/or pinna. Diagnosis is primarily clinical. Erythema, edema, debris, and/or otorrhea of the EAC may be visible on otoscopy; the tympanic membrane (TM) may not be visualized due to swelling. Treatment typically involves topical antimicrobial agents (e.g., antiseptic or antibiotic ear drops) and supportive management (e.g., analgesia, keeping the EAC dry). Systemic antibiotic therapy is indicated in select cases (e.g., spread of infection, risk factors for severe disease).

Malignant otitis externa (MOE) is covered separately.

• Acute otitis externa (AOE): inflammation of the EAC lasting < 6 weeks ^[1]
• Chronic otitis externa (COE): inflammation of the EAC lasting at least 6 weeks to 3 months ^[1][2]

Acute otitis externa ^[2][3]

• Infectious causes
  • Bacterial infections (most common cause of otitis externa)
    • Pseudomonas aeruginosa (∼ 40% of cases), commonly from swimming activities
    • Staphylococcus aureus, Proteus mirabilis, Escherichia coli
  • Viral infections (rare): Herpes zoster, influenza viruses
  • Fungal infections (less common): Aspergillus (accounts for 90% of all fungal otitis externa), Candida
• Noninfectious causes (less common)
  • Seborrheic otitis externa (associated with seborrheic dermatitis)
  • Eczematous otitis externa (a hypersensitivity reaction to pathogens or topical antibiotics)
  • Neurodermatitis (caused by compulsive/psychogenic scratching).
• Risk factors
  • Injury to the skin of the EAC (e.g., cleaning, insertion of foreign objects such as hearing aids or earplugs, excessive itching)
  • Increased moisture in the EAC (e.g., swimming, humid climate)
  • Immunosuppression, e.g., diabetes, HIV

Chronic otitis externa ^[4]

• Idiopathic
• Refractory fungal or bacterial infection
• May be associated with autoimmune diseases, e.g.:
  • Sarcoidosis
  • Amyloidosis
  • Granulomatosis with polyangiitis

Symptoms ^[3]

• Severe ear pain, particularly at night
• Otorrhea
• Intense itching in the EAC
• Hearing loss
• Jaw pain ^[2]

Fever > 38.3 °C (101 °F) suggests infection extending beyond the EAC. ^[2]

Examination findings ^[2][3]

• Tenderness on palpation of the tragus
• Pulling up and back on the auricle causes pain.
• The following may also be present:
  • Crusting of otorrhea at the entrance to the EAC
  • Conductive hearing loss
  • Clinical features of cellulitis
  • Regional lymphadenitis

Otoscopy ^[3]

• Erythematous and edematous EAC
• Otorrhea or debris
• EAC may be occluded by a furuncle, impacted cerumen, or foreign body
• The tympanic membrane may be erythematous but should not bulge.

Severe edema of the EAC may prevent otoscopic examination.

See also “Malignant otitis externa."

Localized otitis externa (furunculosis) ^[3]

Localized OE is an infection of a hair follicle in the distal EAC.

Etiology ^[5]

• S. aureus (most common)
• Group A Streptococcus

Diagnostics

• Clinical diagnosis
• In addition to classic clinical features of OE, a pustular lesion may be present.

Treatment

• Local application of heat
• Incision and drainage
• Systemic antibiotics (see “Empiric antibiotic therapy for skin and soft tissue infections”)

Otomycosis (fungal otitis externa) ^[3]

Etiology ^[3]

• Pathogens
  • Aspergillus spp. (most common)
  • Candida spp.
• Risk factors
  • Immunosuppression (e.g., HIV, diabetes)
  • Long-term antibiotic therapy
  • Residence in a hot, humid area

Diagnostics

• Largely a clinical diagnosis; in addition to classic clinical features of OE, patients may additionally have:
  • Thick debris in the ear canal
  • Visible hyphae (often white, yellow, or black) ^[3][6]
  • Insufficient response to antimicrobial therapy
• Fungal culture is recommended. ^[2]

Treatment ^[3]

• Debridement and cleaning
• Antifungal therapy ^[7]
  • Usually topical, e.g., clotrimazole ear drops
  • Occasionally, systemic (e.g., itraconazole) or combined therapy is required.

General principles ^[3]

• Diagnosis is clinical; AOE is likely if all of the following are present : ^[1][3]
  • Rapid onset of symptoms (typically within 48 hours) within the last 3 weeks
  • Symptoms of EAC inflammation (i.e., otalgia, pruritus, and/or fullness)
  • Examination findings of EAC inflammation (i.e., pinnal and/or tragal tenderness)
• Diagnostic studies are only performed:
  • In suspected comorbid disease
  • To rule out differential diagnoses of otitis externa
  • For refractory disease or suspected subtypes, e.g., MOE

Diagnostic studies ^[3]

• Pneumatic otoscopy and/or tympanometry
  • Perform if there is diagnostic uncertainty between AOE and acute otitis media.
  • Both studies are normal in AOE. ^[3]
• Culture of ear secretions should be obtained if there is: ^[2]
  • Insufficient response to initial treatment
  • ≥ 1 risk factor for a fungal or antibiotic-resistant pathogen
  • Concern the infection has extended beyond the EAC
• Screening for comorbidities: Consider based on clinical features.
  • AOE: screening for diabetes or screening for HIV, especially if otomycosis is suspected or confirmed ^[3]
  • COE: screening for autoimmune disease ^[8]
• Patients with clinical features of MOE: see “Diagnostics of MOE”.

The differential diagnoses listed here are not exhaustive.

The following applies to diffuse acute OE. For localized OE and otomycosis, see “Subtypes and variants.” Treatment of COE differs by underlying cause (e.g., fungal, allergic, or autoimmune).

Approach ^[2][3]

• Provide supportive therapy as needed (e.g., analgesia, aural toilet).
• Initiate antimicrobial treatment.
  • Start topical therapy; insert an ear wick if the EAC is significantly swollen. ^[3]
  • If indications for systemic antibiotic therapy in AOE are present, add oral antibiotics.
• Provide patient education on:
  • Counseling for otic medications
  • Prevention of OE
• Refer to otolaryngology for: ^[9]
  • Severe infection (e.g., indications for systemic antibiotics for OE) or persistent symptoms
  • Need for procedural interventions
• If the patient doesn't notice improvement within 48–72 hours, reassess and consider: ^[3]
  • Alternative diagnoses: MOE, differential diagnoses of OE
  • Treatment adherence
  • Modifying management

If clinical features of MOE are present, admit to the hospital in consultation with otolaryngology and initiate immediate treatment of MOE. ^[3][10]

If patients do not respond to initial topical therapy, consider alternative diagnoses such as allergic contact dermatitis, otomycosis, or MOE. ^[3]

Supportive therapy ^[3]

• Oral analgesia ^[3][11]
  • Common agents: ibuprofen, acetaminophen
  • See “Oral analgesia in adults” and “Oral analgesia in children” for dosing and alternative agents.
• Aural toilet
  • Removal of EAC debris improves the delivery of topical therapy and hastens recovery. ^[2][3]
  • Contraindications include: risk factors for MOE, nonintact TM

Aural toilet can be painful for patients with severe inflammation; give preemptive analgesia and consider procedural sedation. ^[3]

If the EAC is obstructed with debris in a patient with contraindications to aural toilet (e.g., risk factors for MOE, nonintact TM), refer to otolaryngology. ^[3]

Topical antimicrobials for OE ^[2][3]

An antimicrobial ear drop, which may contain a glucocorticoid, is prescribed; for 7–10 days; consider administering the first dose in-office. ^[3]

• Ototoxic agents: only indicated for visualized, intact TMs
  • Antiseptics
    • Acetic acid
    • Acetic acid with hydrocortisone
  • Aminoglycosides: neomycin/polymyxin B/hydrocortisone
• Non-ototoxic agents (e.g., fluoroquinolones): may be used regardless of TM patency
  • Ciprofloxacin with hydrocortisone
  • Ciprofloxacin with dexamethasone
  • Ofloxacin

If allergic contact dermatitis caused by ototopical agents (e.g., neomycin) is suspected, discontinue the agent and treat with a topical glucocorticoid. ^[2]

To prevent ototoxicity and iatrogenic hearing loss, use fluoroquinolone eardrops in patients with a nonvisualized or nonintact TM. ^[3]

Systemic antibiotics for OE ^[2][3]

• Indications for systemic antibiotics for OE
  • Inability to administer topical antimicrobials
  • Infection extending beyond the EAC (e.g., cellulitis, MOE) or concurrent acute otitis media
  • Risk factors for MOE or previous radiotherapy of the ear
• Agents should provide coverage for P. aeruginosa and S. aureus, e.g., ciprofloxacin (off-label in children) ^[9][12]

These interventions are based on expert recommendations but lack high-quality supporting evidence. ^[2][9]

• Avoid inserting objects into the ear canal (e.g., cotton swabs, earbud headphones).
• Regularly remove and clean earrings and in-ear devices (e.g., hearing aids).
• Treat underlying chronic dermatological conditions.
• Frequent swimmers: Use a tight-fitting bathing cap or earplugs. ^[3][9][13]
• After bathing or swimming ^[9]
  • Tilt the head to remove water.
  • Dry the ears with a blow-dryer at the lowest heat setting.
• Consider prophylactic ear drops (e.g., acetic acid ) for recurrent OE with intact TMs. ^[2][9][14]