Otitis externa

Otitis externa is an extremely common infection during the summer months. It is often associated with water-based activities such as swimming and diving and is a frequent cause of earache in children. Water retained in the external ear canal (EAC) macerates the skin, softening sloughed keratinocytes and creating an environment in which pathogens flourish. The heat and humidity of summer also contribute to pathogen growth.

Aggressive ear cleaning encourages the growth of bacteria in several ways. Normally, cerumen helps to maintain a bacteriostatic acidic pH in the ear canal. It is also hydrophobic, creating a barrier to water. In addition, use of swabs or other devices to clean the ears can traumatize the thin skin of the ear canal, and lead to retained fragments of organic debris that encourage the growth pathogenic bacteria.

The most common organisms cultured in external otitis are Pseudomonas aeruginosa, Staphylococcus epidermidis, and Staphylococcus aureus, in that order. The condition typically presents with a combination of symptoms including ear pain, itching, discharge from the external auditory canal, and, because of swelling and accumulation of debris, conductive hearing loss

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On examination, the tragus is often tender, and manipulating or pulling on the pinna may also elicit pain. The skin of the EAC is erythematous and swollen. Yellow or white debris may be visible, and it is sometimes difficult to visualize the tympanic membrane.

Gently clearing the debris is important for several reasons. It allows assessment of the integrity of the tympanic membrane. Otorrhea and ear pain can be caused by otitis media with tympanic membrane rupture. Most otitis externa is treated topically so clearing the debris allows more effective contact of the medication with the infected skin. 

Some of the topical therapies for otitis externa can cause ototoxicity when used in the presence of a nonintact tympanic membrane. Referral to an otolaryngologist is appropriate when the tympanic membrane cannot be visualized. The ear, nose, and throat doctor (ENT) will use a vacuum device with microscopy to clear debris and determine appropriate therapy.

A large number of topical solutions and suspensions for the treatment of otitis externa are available. Although solutions that acidify the local environment and contain antiseptics (such as acetic acid or boric acid and alcohol combinations) can be effective, the most commonly used preparations are combinations of antibiotics and steroids. 

Prior to the advent of topical fluoroquinolones, a combination of neomycin, polymyxin B, and hydrocortisone acetate was commonly prescribed. It is effective and inexpensive but risks topical sensitization from the neomycin. Topical fluoroquinolones in combination with steroids, such as ciprofloxacin/hydrocortisone, have proven effective with less potential for adverse events.3

If the infection has spread beyond the EAC, referral to an ENT is necessary. Cellulitis requires systemic therapy. When pain is out of proportion to physical findings, especially in the elderly and immune compromised (including diabetics), consider the possibility of malignant otitis externa, in which the pathogens erode into bone causing a potentially fatal infection.

The pain of typical otitis externa can be mild, moderate, or severe and is usually best treated with nonsteroidal anti-inflammatory drugs (NSAIDs), though oral narcotics are sometimes useful. Patients should be advised to avoid swimming while their infection is active, along with limiting the use of earplugs, ear buds, and other occluding devices that can retain moisture in the EAC.