OTITIS EXTERNA

Timothy C. Hain, MD Page last modified: February 7, 2010

DEFINITIONS

Otitis externa (OE) is an infection of external ear canal

GENERAL SIGNS AND SYMPTOMS:

Persons with OE present with pain, drainage and loss of hearing.

Causes of Otitis Externa

Otitis externa is most commonly caused by

• staphylococcus (about 50%)
• MRSA (about 10%)
• pseudomonas (about 30%)

Fungi (otomycosis) are usually accompanying organisms, but can be the primary cause of otitis media or otitis externa.

Treatment of Otitis Externa

Cultures of draining ears are recommended at the initial visit. However, the impact on management is uncertain.

• Meticulous cleaning using a microscope. This may require several visits.
• Ear drops are generally used to treat otitis externa.
  • Presently most patients are started on a drop that contains a floroquinolone, possibly with the addition of a steroid to reduce swelling.
• An antibiotic pack may be used, using a 1/4" gauze (in an adult).
• If ear drops fail, then systemic antibiotics follow.
  • Systemic antibiotics are not recommended as the first line of treatment (Hamerlynck et al., 2006).
• Because of the bacteriology of OE (staph, pseudomonas, MRSA, fungus), somewhat unusual systemic antibiotics may be used.
  • This may include high-dose trimethoprim sulfa (for MRSA).

Prevention measures for recurrence include the following (Sander, 2001)

• Avoid manipulation of ear canal (i.e. avoid putting things in the ear canal)
• Dry and clean ear
  • Dry ears with hair dryer
  • Boric acid powder dusting can be used to dry the ear (particularly with hearing aids)
  • Clean ears in doctor's office with suction/microscope
• Acidification (2% acetic acid with hydrocortisone) -- Vosol is a brand name for this preparation. The usual dose is 3-4 drops in the affected ear three times/day. Not used in persons with perforation.

When acidification fails, antifungal topical preparations are also commonly used. There are numerous of these agents used in animal medicine. None of these is presently FDA approved for human use and for this reason they are used "off-label" in humans. Several of these are available over-the-counter such as clotrimazole -- (Lotrimin AF) cream and tinactin solution. Use of these preparations should be under the supervision of a physician experienced in treating ear infections.

Treatment of fungal external otitis.

This is generally recognized by failure or partial resposne to treatment for acute external otitis. Typical organisms are candida and aspergillus. One should rule out metabolic and immunological disorders, i.e. diabetes, cancer chemotherapy, leukemia, and HIV among others. The ear should be carefully cleaned, and an anti-fungal cream such as Nizoral or Lotromin considered. There shold be repeat cleaning and application of the antifungal every 10-14 days. (Farrior, 2000)

References

• Farrior JB. Practice office treatment of ear disease. Presentation handout to American Academy of Otolaryngology, Sept 24-27, 2000
• Hamerlynck, J. V., P. P. van Benthem, et al. (2006). "[From the Cochrane Library: topical antibiotic treatment is more effective than systemic antibiotic treatment for chronic otitis media with eardrum perforation and purulent discharge]." Ned Tijdschr Geneeskd 150(37): 2033-5.
• Sander, R. (2001). "Otitis externa: a practical guide to treatment and prevention." Am Fam Physician 63(5): 927-36, 941-2.