|
External otitis is an acute infection of the ear canal, typically by bacteria (Pseudomonas is most common). Symptoms include itching, pain, discharge, and hearing loss if the ear canal has swollen shut; any manipulation of the auricle causes pain. Diagnosis is based on inspection. Treatment is with topical drugs, including antibiotics, corticosteroids, and acetic acid or a combination.
External otitis may manifest as a localized furuncle or as a diffuse infection of the entire canal (generalized or acute external otitis). This condition is often called swimmer's ear; the combination of water in the canal and use of cotton swabs is the major risk factor. Malignant external otitis (see External Ear Disorders: Malignant External Otitis) is a severe Pseudomonas infection of the temporal bone affecting diabetics and immunocompromised patients.
Etiology
Diffuse external otitis is usually caused by bacteria, such as Pseudomonas aeruginosa,
Proteus vulgaris,
Staphylococcus aureus, or Escherichia coli. Fungal external otitis (otomycosis), typically caused by Aspergillus niger or Candida albicans, is less common. Furuncles usually are caused by S. aureus.
Predisposing conditions include allergies, psoriasis, eczema, seborrheic dermatitis, decreased canal acidity (possibly due to the repeated presence of water), irritants (eg, hair spray, hair dye), and inadvertent injury to the canal caused by cleaning with cotton swabs or other objects. Attempts to clean the ear canal with cotton swabs can cause microabrasions of the delicate skin of the ear canal (which act as portals of entry for bacteria) and may push debris and cerumen deeper into the canal. These accumulated substances tend to trap water, resulting in skin maceration that sets the stage for bacterial infection.
Symptoms and Signs
Patients have itching and pain. Sometimes, a foul-smelling discharge and hearing loss occur if the canal becomes swollen or filled with purulent debris. Exquisite tenderness accompanies traction of the pinna or pressure over the tragus. Otoscopic examination is painful and difficult to conduct. It shows the ear canal to be red, swollen, and littered with moist, purulent debris.
Otomycosis is more pruritic than painful, and patients also complain of aural fullness. Otomycosis caused by A. niger usually manifests with grayish black or yellow dots (fungal conidiophores) surrounded by a cottonlike material (fungal hyphae). Infection caused by C. albicans does not show any visible fungi but usually contains a thickened, creamy white exudate.
Furuncles cause severe pain and may drain sanguineous, purulent material. They appear as a focal, erythematous swelling (pimple).
Diagnosis
Diagnosis is based on inspection. When discharge is copious, external otitis can be difficult to differentiate from perforated otitis media; pain with pulling on the pinna may indicate an external otitis. Fungal infection is diagnosed by appearance or culture.
Treatment
In acute external otitis, topical antibiotics and corticosteroids are effective. First, the infected debris should be gently and thoroughly removed from the canal with suction or dry cotton wipes. Water irrigation of the canal is strongly discouraged. Mild external otitis can be treated by altering the ear canal's pH with 2% acetic acid and by relieving inflammation with topical hydrocortisone; these are given as 5 drops tid for 7 days. Moderate external otitis requires the addition of an antibacterial solution or suspension, such as neomycin/polymyxin, ciprofloxacin, or ofloxacin. When inflammation of the ear canal is relatively severe, an ear wick should be placed into the ear canal and wetted with a topical antibiotic 4 times/day. The wick helps direct the drops deeper into the external canal when the canal is greatly swollen. The wick is left in place for 24 to 72 h, after which time the swelling may have receded enough to allow the instillation of drops directly into the canal.
Severe external otitis or the presence of cellulitis extending beyond the ear canal may require systemic antibiotics, such as cephalexin 500 mg po tid for 10 days or ciprofloxacin 500 mg po bid for 10 days. An analgesic, such as an NSAID or even an oral opioid, may be necessary for the first 24 to 48 h.
Fungal external otitis requires thorough cleaning of the ear canal and application of an antimycotic solution (eg, gentian violet, cresylate acetate, nystatin, clotrimazole, or even a combination of acetic acid and isopropyl alcohol [as long as the eardrum is intact]). Repeated cleanings and treatments may be needed.
A furuncle, if obviously pointing, should be incised and drained. Incision is of little value, however, if the patient is seen at an early stage. Topical antibiotics are ineffective; oral antistaphylococcal antibiotics should be given. Analgesics, such as oxycodone with acetaminophen, may be necessary for pain relief. Dry heat can also lessen pain and hasten resolution.
Prevention
External otitis often can be prevented by applying a few drops of a 1:1 mixture of rubbing alcohol and vinegar (as long as the eardrum is intact) immediately after swimming. The alcohol helps remove water, and the vinegar alters the pH of the canal. Use of cotton swabs or other implements in the canal should be strongly discouraged.
Key Points
Last full review/revision November 2012 by Bradley W. Kesser, MD
Content last modified January 2013
| 
