otitis externa

(redirected from External Otitis)
Also found in: Dictionary, Thesaurus, Encyclopedia.
Related to External Otitis: otitis media, outer ear infection

Otitis Externa



Otitis externa refers to an infection of the ear canal, the tube leading from the outside opening of the ear in towards the ear drum.


The external ear canal is a tube approximately 1 in (2.5 cm) in length. It runs from the outside opening of the ear to the start of the middle ear, designated by the ear drum or tympanic membrane. The canal is partly cartilage and partly bone. In early childhood, the first two-thirds of the canal is made of cartilage, and the last one-third is made of bone. By late childhood, and lasting throughout all of adulthood, this proportion is reversed, so that the first one-third is cartilage, and the last two-thirds is bone. The lining of the ear canal is skin, which is attached directly to the covering of the bone. Glands within the skin of the canal produce a waxy substance called cerumen (popularly called earwax). Cerumen is designed to protect the ear canal, repel water, and keep the ear canal too acidic to allow bacteria to grow.

Causes and symptoms

Bacteria, fungi, and viruses have all been implicated in causing ear infections called otitis externa. The most common cause of otitis externa is bacterial infection. The usual offenders include Pseudomonas aeruginosa, Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae, Staphylococcus epidermidis, and bacteria of the family called Streptococci. Occasionally, fungi may cause otitis externa. These include Candida and Aspergillus. Two types of viruses, called herpesvirus hominis and varicella-zoster virus, have also been identified as causing otitis externa.
Otitis externa occurs most often in the summer months, when people are frequenting swimming pools and lakes. Continually exposing the ear canal to moisture may cause significant loss of cerumen. The delicate skin of the ear canal, unprotected by cerumen, retains moisture and becomes irritated. Without cerumen, the ear canal stops being appropriately acidic, which allows bacteria the opportunity to multiply. Thus, the warm, moist, dark environment of the ear canal becomes a breeding ground for bacteria.
Other conditions predisposing to otitis externa include the use of cotton swabs to clean the ear canals. This pushes cerumen and normal skin debris back into the ear canal, instead of allowing the ear canal's normal cleaning mechanism to work, which would ordinarily move accumulations of cerumen and debris out of the ear. Also, putting other items into the ear can scratch the canal, making it more susceptible to infection.
The first symptom of otitis externa is often itching of the ear canal. Eventually, the ear begins to feel extremely painful. Any touch, movement, or pressure on the outside structure of the ear (auricle) may cause quite severe pain. This is because of the way in which the skin lining the ear canal is directly attached to the covering of the underlying bone. If the canal is sufficiently swollen, hearing may become muffled. The canal may appear swollen and red, and there may be evidence of greenish-yellow pus.
In severe cases, otitis externa may have an accompanying fever. Often, this indicates that the outside ear structure (auricle) has become infected as well. It will become red and swollen, and there may be enlarged and tender lymph nodes in front of, or behind, the auricle.
A serious and life-threatening otitis externa is called malignant otitis externa. This is an infection which most commonly affects patients who have diabetes, especially the elderly. It can also occur in other patients who have weakened immune systems. In malignant otitis externa, a patient has usually had minor symptoms of otitis externa for some months, with pain and drainage. The causative bacteria is usually Pseudomonas aeruginosa. In malignant otitis externa, this bacteria spreads from the external canal into all of the nearby tissues, including the bones of the skull. Swelling and destruction of these tissues may lead to damage of certain nerves, resulting in spasms of the jaw muscles or paralysis of the facial muscles. Other, more severe, complications of this very destructive infection include meningitis (swelling and infection of the coverings of the spinal cord and brain), brain infection, or brain abscess (the development of a pocket of infection with pus).


Diagnosis of uncomplicated otitis externa is usually quite simple. The symptoms alone, of ear pain worsened by any touch to the auricle, are characteristic of otitis externa. Attempts to examine the ear canal will usually reveal redness and swelling. It may be impossible (due to pain and swelling) to see much of the ear canal, but this inability itself is diagnostic.
If there is any confusion about the types of organisms causing otitis externa, the canal can be gently swabbed to obtain a specimen. The organisms present in the specimen can then be cultured (allowed to multiply) in a laboratory, and then viewed under a microscope to allow identification of the causative organisms.
If the rare disease malignant otitis externa is suspected, computed tomography scan (CT scan) or magnetic resonance imaging (MRI) scans will be performed to determine how widely the infection has spread within bone and tissue. A swab of the external canal will not necessarily reveal the actual causative organism, so some other tissue sample (biopsy) will need to be obtained. The CT or MRI will help the practitioner decide where the most severe focus of infection is located, in order to guide the choice of a biopsy site.


Antibiotics which can be applied directly to the skin of the ear canal (topical antibiotics) are usually excellent for treatment of otitis externa. These are often combined in a preparation which includes a steroid medication. The steroid helps cut down on the inflammation and swelling within the ear canal. Some practitioners prefer to insert a cotton wick into the ear canal, leaving it there for about 48 hours. The medications are applied directly to the wick, enough times per day to allow the wick to remain continuously saturated. After the wick is removed, the medications are then put directly into the ear canal three to four times each day.
In malignant otitis externa, antibiotics will almost always need to be given through a needle in the vein (intravenously or IV). If the CT or MRI scan reveals that the infection has spread extensively, these IV antibiotics will need to be continued for six to eight weeks. If the infection is in an earlier stage, two weeks of IV antibiotics can be followed by six weeks of antibiotics by mouth.


The prognosis is excellent for otitis externa. It is usually easily treated, although it may tend to recur in certain susceptible individuals. Left untreated, malignant otitis externa may spread sufficiently to cause death.


Keeping the ear dry is an important aspect of prevention of otitis externa. Several drops of a mixture of alcohol and acetic acid can be put into the ear canal after swimming to insure that it dries adequately.
The most serious complications of malignant otitis externa can be avoided by careful attention to early symptoms of ear pain and drainage from the ear canal. Patients with conditions that put them at higher risk for this infection (diabetes, conditions which weakened the immune system) should always report new symptoms immediately.



American Academy of Otolaryngology-Head and Neck Surgery, Inc. One Prince St., Alexandria VA 22314-3357. (703) 836-4444. http://www.entnet.org.

Key terms

Auricle — The external structure of the ear.
Biopsy — The removal and examination, usually under a microscope, of tissue from the living body. Used for diagnosis.
Cerumen — Earwax.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


inflammation of the ear. adj., adj otit´ic.
aviation otitis a symptom complex due to difference between atmospheric pressure of the environment and air pressure in the middle ear; called also barotitis media.
otitis exter´na inflammation of the external ear, usually caused by a bacteria or fungus. See also otomycosis.
otitis externa, circumscribed acute bacterial otitis externa in a limited area, with formation of a furuncle that may obstruct the canal; usually due to a staphylococcal infection. Called also furuncular otitis externa.
otitis externa, diffuse otitis externa involving a relatively wide area, without formation of a furuncle.
otitis externa, furuncular circumscribed otitis externa.
otitis externa, malignant a progressive, necrotizing infection of the external auditory canal caused by Pseudomonas aeruginosa and affecting chiefly elderly diabetic and immunocompromised patients. It begins with the formation of granulation tissue in the external auditory canal, followed by localized chondritis and osteomyelitis, extension to the tissues surrounding the ear with destruction of involved bone, and involvement of the cranial nerves at the base of the skull; mortality in patients with nerve involvement is high.
furuncular otitis circumscribed otitis externa.
otitis inter´na labyrinthitis.
otitis me´dia inflammation of the middle ear, usually seen in infants and young children, and classified as either serous (or secretory) or suppurative (or purulent). Both types characteristically result in accumulations of fluid behind the tympanic membrane with some degree of hearing loss.
Serous Otitis Media. In this condition the eustachian tube fails to maintain equality of the barometric pressure within and outside the middle ear. When the tube fails to open and close as it should, air within the middle ear is under negative pressure. This causes inward retraction of the eardrum and movement of serous fluid from the mucosal capillaries into the middle ear space. The serous fluid can fill up the space and cause conductive hearing loss.

Acute serous otitis media usually follows an upper respiratory infection or trauma to the ear or may be associated with an allergy or enlarged adenoids. Symptoms are mild and may consist only of a feeling of fullness in the ear and some evidence of hearing loss. Otitis media with effusion is fluid in the middle ear with no signs or symptoms of infection.
Suppurative Otitis Media. The introduction of pus-producing bacteria into the middle ear causes this condition. It usually is associated with an upper respiratory infection, particularly when organisms from the nasopharynx find their way into the middle ear via the eustachian tube.

Symptoms include irritability, difficulty in sleeping, some pain, and loss of hearing. If sufficient pressure builds up behind the tympanic membrane it may rupture spontaneously and exude a purulent discharge. If the pus-laden fluid breaks through internally it can result in intracranial abscess, meningitis, and mastoiditis. Acute suppurative otitis media is treated aggressively with antibacterials and tympanocentesis to relieve pressure and obtain fluid for culturing. If the condition becomes chronic there is continuous otorrhea and hearing loss. Treatment includes systemic antibacterials, topical therapy with ear drops, tympanoplasty to repair a ruptured ear drum and damaged ossicles, and, sometimes, mastoidectomy to eliminate all sources of infection.
Otitis Media with Effusion. is fluid in the middle ear with no signs or symptoms of infection. management. The American Academy of Pediatrics has developed clinical guidelines called Managing Otitis Media With Effusion in Young Children. They recommend the use of pneumatic otoscopy to assess middle ear status and tympanometry. Children who have had fluid in both middle ears for a total of three months should undergo hearing evaluation. Observation or antibiotic therapy are treatment options if the effusion has been present for less than four to six months. Most cases of otitis media with effusion resolve spontaneously.

Three sets of guidelines are available: the aforementioned (AHCPR Publication 94-0623); Otitis Media with Effusion in Young Children (AHPCR Publication 94-0622); and Middle Ear Fluid in Children: Parent Guide (AHCPR Publication 94-0624). Copies can be obtained by writing the AHCPR Publications Clearinghouse, P.O. Box 8547, Silver Spring, MD 20907, calling 1-800-358-9295, or consulting their web site at http://www.ahcpr.gov.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

o·ti·tis ex·ter·'na

inflammation of the external auditory canal.
Synonym(s): swimmer's ear
Farlex Partner Medical Dictionary © Farlex 2012

otitis externa

Outer ear infection, swimmer's ear ENT Inflammation of the outer ear and auditory canal to the tympanic membrane, which most often affects adolescents, linked to recent exposure to water or mechanical ear trauma from scratching or foreign objects in the ear, hair spray, hair dyes, shampoos, and other chemicals which irritate the skin of the ear canal; OE may be associated with otitis media, URIs, common cold; moisture in the ear predisposes it to infections– fungal, Pseudomonas spp, Proteus spp
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

o·ti·tis ex·ter·na

(ō-tī'tis eks-ter'nă)
Inflammation of the external auditory canal, usually due to bacterial or fungal infection; swimming, cerumen accumulation, presence of a foreign body, and trauma may all be predisposing factors.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

otitis externa

Inflammation of the skin of the ear canal or of the external ear (pinna). This is commonly the result of infection with one of a variety of organisms such as staphylococci, herpes viruses, and fungi of various kinds, including the thrush fungus Candida albicans.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

o·ti·tis ex·ter·na

(ō-tī'tis eks-ter'nă)
Inflammation of the external auditory canal, usually due to bacterial or fungal infection; swimming, cerumen accumulation, foreign body, and trauma may all be predisposing factors.
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
In the evaluation of the culture results on Day 1 of the treatment, with the exception of the control group (Group I), reproduction was determined in all the ears in which the external otitis model was created.
Cranial nerve involvement in malignant external otitis: Implications for clinical outcome.
Hyslop Jr., "Invasive external otitis. Report of 21 cases and review of the literature," The American Journal of Medicine, vol.
Clinical records malignant external otitis in an infant.
"For example, although rare in childhood, malignant external otitis is a serious bone infection which mimics acute external otitis and can occur in insulin-dependent diabetics," he said.
Oral ofloxacin therapy for invasive external otitis. Ann Otol Rhinol Laryngol 1991; 100:632-637.
In all, 73 infectious episodes were recorded in 20 of 28 residents in the implicated building, including 43 (59%) skin abscesses, 20 (27%) furuncles, 8 (11%) purulent conjunctivitis, and 2 (3%) external otitis. A mean of seven episodes per month (median 7, range 4-14) peaked in December 1997.
Staphylococcal malignant external otitis. Can Med Assoc J 1982; 126: 155-6.
Rifamycin is also used topically by otolaryngologists for the treatment of cholesteatoma-free chronic otitis media and external otitis. Although potential ototoxic effects of many topical agents have been investigated, the possible ototoxic effect of topical rifamycin application has not been investigated in the literature.
In the past, its cause was almost always necrotizing external otitis (NEO), especially in older adults with diabetes mellitus (DM) and patients with immunosuppressive conditions [1,2].