Otitis externa refers to a variety of conditions causing inflammation and/or infection of the external auditory canal (and/or auricle and tympanic membrane).¹ There are six subgroups of otitis externa:

1. Acute localized otitis externa (furunculosis)
2. Acute diffuse bacterial otitis externa (i.e., “swimmer ear”)
3. Chronic otitis externa
4. Eczematous otitis externa
5. Fungal otitis externa (otomycosis)
6. Invasive or necrotizing (malignant) otitis externa

See “Definition.”

The two most common symptoms are otalgia, ranging from pruritus to severe pain exacerbated by motion (e.g., chewing), and otorrhea. Patients may also experience aural fullness and hearing loss due to swelling and occlusion of the canal. More intense symptoms may occur with bacterial otitis externa, with or without fever, and lymphadenopathy (anterior to tragus).¹ Findings unique to specific forms of the infection include:

• Acute localized otitis externa (furunculosis)¹:
  1. Occurs from infected hair follicles, usually in the outer third of the ear canal, forming pustules and furuncles
  2. Furuncles are superficial and pointing or deep and diffuse
• Impetigo¹:
  1. In contrast to furunculosis, this is a superficial spreading infection of the ear canal that may also involve the concha and the auricle
  2. Begins as a small blister that ruptures, releasing straw-colored fluid that dries as a golden crust
• Erysipelas¹:
  1. Caused by group A streptococcus (Streptococcus pyogenes [GAS])
  2. May involve the concha and canal
  3. May involve the dermis and deeper tissues
  4. Area of cellulitis, often with severe pain
  5. Fever, chills, malaise
  6. Regional adenopathy
• Eczematous or seborrheic otitis externa¹:
  1. Stems from a variety of dermatologic problems that can involve the external auditory canal
  2. Severe itching, erythema, scaling, crusting (Fig.E1), and fissuring possible

• Acute diffuse otitis externa (swimmer ear)¹:
  1. Begins with itching and a feeling of pressure and fullness in the ear that becomes increasingly tender and painful
  2. Mild erythema and edema of the external auditory canal, which may cause narrowing and occlusion of the canal (Fig. E2), leading to hearing loss

1. 3. Minimal serous secretions, which may become profuse and purulent
   4. Tympanic membrane may appear dull and infected
   5. Usually absence of systemic symptoms such as fever, chills
2. Otomycosis¹:
   1. Chronic superficial infection of the ear canal and tympanic membrane
   2. In primary fungal infection, major symptom is intense itching
   3. In secondary infection (fungal infection superimposed on bacterial infection), major symptom is pain
   4. Fungal growth of variety of colors
3. Chronic otitis externa¹:
   1. Dry and atrophic canal
   2. Typically lack of cerumen
   3. Itching, often severe, and mild discomfort rather than pain
   4. Occasionally mucopurulent discharge
   5. With time, thickening of the walls of the canal, causing narrowing of the lumen
4. Necrotizing otitis externa (also known as malignant otitis externa). Typically seen in older patients with diabetes or in patients who are immunocompromised³
   1. Redness, swelling, and tenderness of the ear canal
   2. Classic finding of granulation tissue on the floor of the canal and the bone-cartilage junction
   3. Small ulceration of necrotic soft tissue at bone-cartilage junction
   4. Most common symptoms: Pain (often severe) and otorrhea
   5. Lessening of purulent drainage as infection advances
   6. As the infection advances, osteomyelitis of the base of the skull and temporomandibular joint osteomyelitis can develop
   7. Facial nerve palsy often the first and only cranial nerve defect
   8. Possible involvement of other cranial nerves

• Box 1 summarizes common pathogens in otitis externa
• Acute localized otitis externa: Staphylococcus aureus
• Impetigo:
  1. S. aureus including MRSA
  2. Streptococcus pyogenes (GAS)
• Erysipelas: GAS
• Eczematous otitis externa:
  1. Seborrheic dermatitis
  2. Atopic dermatitis
  3. Psoriasis
  4. Neurodermatitis
  5. Lupus erythematosus
• Acute diffuse otitis externa:
  1. Swimming
  2. Hot, humid climates
  3. Tightly fitting hearing aids
  4. Use of ear plugs
  5. Pseudomonas aeruginosa
  6. S. aureus including MRSA
• Otomycosis:
  1. Prolonged use of topical antibiotics and steroid preparations
  2. Uncontrolled diabetes mellitus can contribute to risk
  3. Aspergillus (80% to 90%)
  4. Candida
• Chronic otitis externa: Persistent low-grade infection and inflammation
• Necrotizing otitis externa (NOE)³:
  1. Complication of persistent otitis externa
  2. Typically starts in the external auditory canal and spreads to the stylomastoid foramen, then to the mastoid tip and the jugular foramen. Finally, it extends to the petrous apex and the middle cranial fossa
  3. P. aeruginosa
  4. High index of suspicion for atypical organisms (MRSA) in patients without diabetes

• Acute otitis media
• Bullous myringitis
• Mastoiditis
• Foreign bodies
• Neoplasms
• Contact dermatitis
• Eczema
• Ramsey-Hunt syndrome
• Seborrhea
• Otomycosis
• Referred pain
• Table 1 describes the differential diagnosis of painful external ear and auditory canal disorders

Thorough history and physical examination, including pneumatic otoscopy if available

• Cultures from the canal are usually not necessary unless the condition does not respond to treatment.
• Leukocyte count normal or mildly elevated.
• Erythrocyte sedimentation rate is often quite elevated in malignant otitis externa.

• Computed tomography scan (Fig. E3) is the best technique for defining bone involvement and extent of disease in malignant otitis externa.

• MRI is slightly more sensitive in evaluation of soft tissue changes and intracranial extension of infection.
• Gallium scans are more specific than bone scans in diagnosing NOE.
• Follow-up scans are helpful in determining efficacy of treatment. note: Expert opinion supports history and physical examination as the best means of diagnosis. Persistent pain that is constant and severe should raise the question of NOE (particularly in the elderly, diabetics, and immunocompromised patients).

• Cleansing and debridement of the ear canal with cotton swabs and hydrogen peroxide or other antiseptic solution allows a more thorough examination of the ear.
• If the canal lumen is edematous and too narrow to allow adequate cleansing, a cotton wick or gauze strip inserted into the canal serves as a conduit for topical medications to be drawn into the canal. Usually remove wick after 2 days.
• Local heat is useful in treating deep furunculosis.
• Incision and drainage is indicated in treatment of superficial pointing furunculosis.

Topical medications:

• An acidifying agent such as 2% acetic acid (Vosol) inhibits growth of bacteria and fungi.
• Topical antibiotics (in the form of otic or ophthalmic solutions) or antifungals, often in combination with an acidifying agent and a steroid preparation. Direct application of topical agents to the infected site is a key element in the treatment of external otitis regardless of severity. Proper installation of eardrops entails tilting the head toward the opposite shoulder, pulling the superior aspect of the auricle upward, and filling the ear canal with drops. In young children, the earlobe should be pulled downward to fill the canal.
• The ideal antibiotic regimen should have coverage against the most common pathogens, S. aureus and P. aeruginosa.
• Side effect profile can also influence choice of treatment. Ototoxicity is the most important concern with aminoglycoside drugs, including neomycin, tobramycin, and gentamicin. Aminoglycosides are a significant potential source for iatrogenic hearing loss and balance dysfunction, particularly in the presence of tympanic membrane perforation. Allergic contact dermatitis is commonly associated with neomycin when used for prolonged courses. Topical fluoroquinolones can cause local irritation.
• The following are some of the available preparations:
  1. Neomycin otic solutions and suspensions:
     1. With polymyxin-B-hydrocortisone (Cortisporin)
     2. With hydrocortisone-thonzonium (Coly-Mycin S)
  2. Polymyxin-B-hydrocortisone (Otobiotic)
  3. Quinolone otic solutions:
     1. Ofloxacin 0.3% solution (Floxin Otic)
     2. Ciprofloxacin 0.3% with hydrocortisone (Cipro HC)
  4. Quinolone ophthalmic solutions:
     1. Ofloxacin 0.3% (Ocuflox)
     2. Ciprofloxacin 0.3% (Ciloxan)
  5. Aminoglycoside ophthalmic solutions:
     1. Gentamicin sulfate 0.3% (Garamycin)
     2. Tobramycin sulfate 0.3% (Tobrex)
     3. Tobramycin 0.3% and dexamethasone 0.1% (TobraDex)
  6. Chloramphenicol 0.5% otic solution or 0.25% ophthalmic solution (Chloromycetin)
  7. Gentian violet (methylrosaniline chloride 1%, 2%)
  8. Antifungals:
     1. Amphotericin B 3% (Fungizone lotion)
     2. Clotrimazole 1% solution (Lotrimin)
     3. Tolnaftate 1% (Tinactin)
• Topical preparations should be applied qid (bid for quinolones, antifungals), generally for 3 days after cessation of symptoms (average 10-14 days total).

Systemic antibiotics:

• Reserved for when the infection has spread beyond the ear canal.
• Treatment usually for 10 days with ciprofloxacin 750 mg q12h or ofloxacin 400 mg q12h, or with antistaphylococcal agent (e.g., dicloxacillin or cephalexin 500 mg q6h). Use Bactrim or clindamycin when MRSA suspected or cultured at one DS twice a day instead of cephalexin or dicloxacillin. For malignant otitis externa (due to Pseudomonas aeruginosa in >90% of cases), effective agents are meropenem 1 g intravenous (IV) q8h or ciprofloxacin 400 mg IV q12h or 750 mg PO q12h or cefepime 2 g q12h.

Treatment for NOE:

• Combined oral quinolones with topical quinolones for 4 to 6 wk may be sufficient for initial therapy.³
• IV antipseudomonals with or without aminoglycosides are appropriate in refractory cases.³
• Local debridement.

Pain control:

• May require NSAIDs or opioids
• Topical corticosteroids to reduce swelling and inflammation

• Patients prone to recurrent infections should try to identify and avoid precipitants to infection.
• Swimmers should try tight-fitting ear plugs or tight-fitting bathing caps and remove all excess water from the ears after swimming.
• Treat underlying systemic diseases and dermatologic conditions that predispose to infection.
• Hearing aids should be removed nightly and regularly cleaned.

• Inadequate treatment of otitis externa may lead to NOE and mastoiditis.
• Considerations if acute otitis externa fails to respond to initial ototopical therapy are summarized in Box 2.
• Complications of acute and chronic otitis externa are summarized in Table 2.

To an otolaryngologist:

• NOE
• Treatment failure
• Severe pain

Otitis Externa (Patient Information)