What Organisms Cause Otitis Externa?

Patient Presentation
A 7-year-old male came to clinic with drainage from his left ear for 2 days. The small amount of drainage was clearish-yellow and came and went over the day.
There was more dried discharge on his pillow in the morning. The ear was somewhat painful but not excruciating and was somewhat pruritic. He denied sore throat, teeth pain or other pain.
He had been swimming in a chlorinated pool and hot tub for several days before the onset of the drainage.
The pertinent physical exam showed a well-appearing male with growth parameters in the 10-50%. His right ear was normal.
His left external canal had pale yellow, thin discharge with white macerated skin and areas of erythema. Part of the tympanic membrane could be visualized and appeared non-erythematous and in normal position.
There was mild pain produced with pressure on the tragus.
There was shoddy anterior cervical adenopathy bilaterally.
The diagnosis of otitis externa was made. The patient was begun on ciprofloxacin otic drops to be used for 5 days and to return if symptoms were not improved.
He was also told to use a few drops of vinegar after swimming and baths to help prevent otitis externa from recurring.

Otitis externa, also known as swimmer’s ear, is a common infection, especially in school age children. Moisture in the ear causes edema, skin breakdown and bacteria to grow. Swelling and debris may obstruct the external canal exacerbating the problem.
Common predisposing factors include swimming (especially in water with high bacterial counts), foreign body (including hearing aids, retained cerumen, insects, etc.), dermatitis, viral infections and local trauma (i.e. finger nails, cotton-tipped applicators, etc.).
Patients usually complain of unilateral ear pain or pruritus, drainage or decreased hearing. On physical examination, pressure on the tragus may elicit pain, and debris/drainage can be seen in the canal.
The skin may look macerated with edema and erythema. The tympanic membrane may or may not be visible. Lymphadenopathy may be palpable and a conductive hearing loss may be measured. Unless infections extend beyond the canal, serious auricular problems usually do not occur.
Cultures are not obtained unless there is an unusual history or physical examination such as a patient who is immunocompromised.

Treatment for pain is usually acetaminophen or ibuprofen but occasionally oral narcotics are needed. Topical anesthetics such as antipyrine/benzocaine can be used but not if there is tympanic membrane perforation as it causes ototoxicity.
Topical antibiotics are usually used. Fluoroquinolones such as ciprofloxacin and ofloxacin are the drugs of choice. Polymyxin B/neomycin/hydrocortisone has been used in the past with good results but increasing bacterial resistance and pain during administration along with sensitivity to neomycin and potential for ototoxicity is limiting it use.
Systemic antibiotics are usually not necessary for most patients but may be used with infections beyond the canal or immunocompromised patients. Historically, some physicians have used a small cotton wick placed into the ear to aid medication delivery but this has not been systematically evaluated.
Prevention centers on trying to keep the external canal as dry as possible. Using ear plugs and/or bathing cap, or blow drying with a low dryer setting after swimming may help. Decreasing the pH of the ear also helps by using a few drops of isopropyl alcohol, acetic acid or boric acid after swimming..

Ofloxacin and ciprofloxacin with dexamethasone may be used with tympanic membrane perforation or pressure-equalizing tubes as they are not ototoxic.

Learning Point
Otitis externa is most commonly caused by Pseudomonas aeruginosa and Staphylococcus aureus. These often co-exist.

Questions for Further Discussion
1. What diseases should be considered in the differential diagnosis of otitis externa?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Information prescriptions for patients can be found at MedlinePlus for this topic: Ear Infections

and at Pediatric Common Questions, Quick Answers for this topic: Otitis Externa

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

Stone KE. Otitis Media. Pediatr Rev. 2007 Feb;28(2):77-8.

Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:1255-1256.

ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effectively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients’ is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    5. Patients and their families are counseled and educated.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    12. Evidence from scientific studies related to the patients’ health problems is located, appraised and assimilated.
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.

    Donna M. D’Alessandro, MD
    Associate Professor of Pediatrics, Children’s Hospital of Iowa

    May 21, 2007