See patient information handout on otitis externa , written by the author of this article. Otitis externa is most commonly caused by infection usually bacterial, although occasionally fungal , but it may also be associated with a variety of noninfectious systemic or local dermatologic processes. The most characteristic symptom is discomfort that is limited to the external auditory canal, while the most characteristic signs are erythema and swelling of the canal with variable discharge.
Excessive moisture and trauma, both of which impair the canal's natural defenses, are the two most common precipitants of otitis externa, and avoidance of these precipitants is the cornerstone of prevention.
Thorough cleansing of the canal is essential for diagnosis and treatment, but flushing should be avoided. Acidification with a topical solution of 2 percent acetic acid combined with hydrocortisone for inflammation is effective treatment in most cases and, when used after exposure to moisture, is an excellent prophylactic.
Other prophylactic measures such as drying the ears with a hair dryer and avoiding manipulation of the external auditory canal may help prevent recurrence. Otitis externa is an inflammatory process of the external auditory canal.
In one recent study, 1 otitis externa was found to be disabling enough to cause 36 percent of patients to interrupt their daily activities for a median duration of four days, with 21 percent requiring bed rest.
It is typically a localized process that can be easily controlled with topical agents, yet physicians use systemic medications to treat this condition 65 percent of the time.
The unique structure of the external auditory canal contributes to the development of otitis externa Figure 1. It is the only skin-lined cul-de-sac in the human body. The external auditory canal is warm, dark and prone to becoming moist, making it an excellent environment for bacterial and fungal growth. The skin is very thin and the lateral third overlies cartilage, while the rest has a base of bone. The canal is easily traumatized. The exit of debris, secretions and foreign bodies is impeded by a curve at the junction of the cartilage and bone.
The presence of hair, especially the thicker hair common in older men, can be a further impediment. Anatomy of the external auditory canal. The outer third of the canal is cartilaginous with hair follicles and sebaceous and ceruminous glands. Fortunately, the external auditory canal has some special defenses. Cerumen creates an acidic coat containing lysozymes and other substances that probably inhibit bacterial and fungal growth. The lipid-rich cerumen is also hydrophobic and prevents water from penetrating to the skin and causing maceration.
Too little cerumen can predispose the ear canal to infection, but cerumen that is excessive or too viscous can lead to obstruction, retention of water and debris, and infection. Additionally, the canal is defended by a unique epithelial migration that occurs from the tympanic membrane outward, carrying any debris with it. When these defenses fail or when the epithelium of the external auditory canal is damaged, otitis externa results.
There are many precipitants of this infection Table 1 , but the most common is excessive moisture that elevates the pH and removes the cerumen. Once the protective cerumen is removed, keratin debris absorbs the water, which creates a nourishing medium for bacterial growth. High humidity. Cotton swabs.
Hearing aids. Ear plugs. Seborrheic dermatitis. The two most characteristic presenting symptoms of otitis externa are otalgia ear discomfort and otorrhea discharge in or coming from the external auditory canal. If inflammation causes sufficient swelling to occlude the external auditory canal, the patient may also complain of aural fullness and loss of hearing. Its characteristics often may give a clue to its etiology Table 2.
Acute bacterial. Chronic bacterial. Typically fluffy and white to off-white discharge, but may be black, gray, bluish-green or yellow; small black or white conidiophores on white hyphae associated with Aspergillus. Otorrhea and other debris can occlude the ear canal. Such occlusion makes it difficult to visualize the tympanic membrane and exclude otitis media; it also keeps the canal moist and interferes with topical treatment. It is imperative that this material be removed. However, inflammation makes the external auditory canal even more vulnerable to trauma than usual, and therefore the use of a cerumen spoon or curette should be avoided.
Cleansing is best done by suctioning under direct visualization, using the open or operating otoscope head and a 5 or 7 Fr Frazier malleable suction tip attached to low suction. Alternatively, a cotton swab with the cotton fluffed out can be used to gently mop out thin secretions from the external auditory canal, again under direct visualization Figure 2.
If the secretions are thick, crusted or adherent, instillation of antibiotic drops or hydrogen peroxide may help to soften them for removal. Unless the tympanic membrane can be fully observed and is found to be intact, flushing of the ear canal should not be attempted. A small perforation is often missed, and a tympanic membrane already weakened by infection can easily be disrupted.
Divers, surfers and others who experience forceful compression of the tympanic membrane are particularly susceptible to perforations. Such damage may necessitate surgery, and a perforated tympanic membrane associated with flushing is a common cause of litigation.
If the external auditory canal cannot be easily cleansed because of swelling or pain, discharge and debris should be left in place and the patient should undergo frequent reevaluation until the secretions can be removed or have drained spontaneously. When the canal is quite swollen, a cotton wick specifically designed for this purpose should be placed to facilitate drainage and permit application of topical medications. A thorough examination of the head and neck should be performed to rule out other diagnoses and to look for possible complications of otitis externa.
The examination should include evaluation of the sinuses, nose, mastoids, temporomandibular joints, mouth, pharynx and neck. In addition, if the tympanic membrane can be visualized and is red, a pneumatoscope or tympanometry should be used to ascertain whether associated otitis media is present. The most common cause of otitis externa is a bacterial infection, although fungal overgrowth is a principal cause in 10 percent of cases. Like all skin, the external auditory canal has a normal bacterial flora and remains free of infection unless its defenses are disrupted.
When disruption occurs, a new pathogenic flora develops that is dominated by Pseudomonas aeruginosa and Staphylococcus aureus. The signs and symptoms of otitis externa with a bacterial etiology tend to be more intense than in other forms of the disease. Otalgia may be severe enough to require systemic analgesics such as codeine and non-steroidal anti-inflammatory drugs NSAIDs. Fever may be present, but if it exceeds Lymphadenopathy just anterior to the tragus is common. Once the external auditory canal has been cleansed as much as possible and a wick inserted if swelling is severe, topical antibacterial therapy should be started.
Because topical agents can be placed in direct contact with the bacteria, simple acidification with 2 percent acetic acid is usually effective, but a wide spectrum of other agents is available Tables 3 and 4. With aluminum acetate Otic Domeboro. With polymyxin B—hydrocortisone Cortisporin.
With hydrocortisone-thonzonium Coly-Mycin S. Ofloxacin 0. Ciprofloxacin 0. Gentamicin sulfate 0. Tobramycin sulfate 0. Based on average wholesale prices in Red book. Montvale, N. Cost to the patient will be higher, depending on prescription filling fee. Generic product is inexpensive and effective against most infections without causing sensitization. Highly effective without causing local irritation or sensitization; no risk of ototoxicity; twice-daily dosing.
Expensive; increased community exposure of an important class of antibiotics, with potential for causing resistance. The addition of steroids to the ear drops may decrease the inflammation and edema of the canal and resolve symptoms more quickly, but not all studies have shown a benefit. In addition, a topical steroid can be a topical sensitizer. Treatment recommendations vary somewhat, but it is most commonly recommended that drops be given for three days beyond the cessation of symptoms typically five to seven days ; however, in patients with more severe infections, 10 to 14 days of treatment may be required.
There is no need for reevaluation unless the infection is not resolving. A small cotton plug moistened with the drops can be used to help retain the drops in the ear if the patient cannot lie still long enough to allow absorption. Absorption may also be facilitated by manipulating the tragus to help distribute the drops throughout the external auditory canal. When a wick is required, drops should be applied every three to four hours while the patient is awake.
In these cases, the ear canal should be reexamined and cleansed every two to five days until edema of the canal has resolved and the wick is no longer needed. Oral antibiotics are rarely needed 2 but should be used when otitis externa is persistent, when associated otitis media may be present or when local or systemic spread has occurred. The latter should be suspected if the patient's temperature is higher than Otitis media should be considered when the patient has had an upper respiratory infection or is younger than two years, an age when otitis externa is uncommon.
Systemic antibiotics also should be considered when the patient has even early signs of necrotizing otitis externa, as described later. Finally, consideration also should be given to starting oral antibiotics early in patients whose immunity may be compromised, such as those with diabetes, those taking systemic corticosteroids or those with an underlying chronic dermatitis. Because ofloxacin otic solution Floxin Otic is the only topical agent to be labeled by the U.
Food and Drug Administration FDA for use when the tympanic membrane is perforated, 19 oral antibiotics have traditionally been used in this situation. However, because the risk of cochlear damage with the use of other topical medications seems quite small, perforation alone is not an indication for oral antibiotics.
When a patient is in a toxic state or the infection is unresponsive to treatment with oral antibiotics, especially in the presence of severe pain and granulation tissue in the ear canal, parenteral antibiotics should be used. Although topical cultures may be misleading, they are recommended by some authors 6 to help guide treatment in such severe infections. Patients who do not respond rapidly to parenteral therapy should be referred to an otolaryngologist.
Whether oral or parenteral, empiric treatment should cover Pseudomonas and Staphylococcus species. This would include agents such as the cephalosporins, penicillinase-resistant penicillins and fluoroquinolones. Necrotizing or malignant otitis externa is a life-threatening extension of external otitis into the mastoid or temporal bone.
Most commonly caused by P. However, all immunocompromised patients, especially those with human immunodeficiency virus HIV infection, are at risk. Necrotizing otitis externa is difficult to treat, and the mortality rate can be as high as 53 percent.
This condition should be suspected when, despite adequate topical treatment, otalgia and headache are disproportionately more severe than the clinical signs or when granulation tissue is apparent at the bony cartilaginous junction. The diagnosis should be confirmed by a computed tomographic CT scan or magnetic resonance imaging MRI. A combination of technetium scanning to detect osteoblastic activity and gallium 67 imaging to detect granulocytic activity can be used in questionable cases and is recommended by some 4 , 25 as a means of monitoring response to treatment.
The erythrocyte sedimentation rate ESR can also be used to monitor therapeutic response. The excellent antipseudomonal activity of the fluoroquinolones has generally made them the treatment of choice for necrotizing otitis externa, although a combination of a beta-lactam antibiotic and aminoglycoside is also effective. Treatment should also include surgical debridement of any granulation or osteitic bone.
Another potential complication of otitis externa is a focal furuncle of the lateral third of the external auditory canal, which can occur as a result of obstructed apopilosebaceous glands. Tilt head back and forth so that each ear faces down to allow water to escape the ear canal. Pull earlobe in different directions when ear faces down to help water drain out.
If there is still water in the ear, consider using a hair dryer to move air within the ear canal. Hold the hair dryer several inches from ear. Check with your healthcare provider about using ear-drying drops after swimming.
Ear wax helps protect the ear canal from infection. If you think the ear canal could be blocked by ear wax, check with your healthcare provider. More Information. Healthy Water Sites. Kromhout , and M. Author information Copyright and License information Disclaimer. Copyright notice. This article has been cited by other articles in PMC. Abstract OBJECTIVE--To determine whether an outbreak of otitis externa was due to bathing in recreational fresh water lakes and to establish whether the outbreak was caused by Pseudomonas aeruginosa in the water.
Studies of bathing water quality and health. Swimming-associated gastroenteritis and water quality. Am J Epidemiol. A prospective study of swimming-related illness. Swimming-associated health risk. Am J Public Health. Morbidity and the microbiological quality of water.
Health effects of beach water pollution in Hong Kong. Epidemiol Infect. Health risks associated with bathing in sea water.
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