My 19-year-old daughter is a lifeguard, and the ocean is at times very contaminated. As a result of the high bacteria levels in the ocean, she has an ear infection that won't go away. She is on her second batch of antibiotics. The infection appears to be creeping to outside the ear. The skin just outside the ear is peeling and itchy. She teaches a program where children learn to be lifeguards, so she is in the water a lot. She is trying not to get water in her ear. I am nervous that the infection will spread to another part of her body. What are your thoughts on this?

S.S.

The condition you describe is either otitis externa, which is an infection of the ear canal skin, or external auditory canal eczema, which is chronic inflammation of this skin. The two conditions may coexist, and both are very treatable.

We have previously discussed the treatment of swimmer's ear, which is another name for otitis externa. As suggested by your letter, one of the key elements of the treatment of swimmer's ear is the avoidance of water. That's because the bacteria that cause swimmer's ear love a warm, moist environment. Also, the ear canal is usually a bit acidic, thanks to earwax. This acidity discourages bacterial overgrowth. Water has a neutral pH (it is neither basic nor acid), so it tends to decrease the acidity of the ear canals. Water thus interferes with the ear canal's natural resistance to infection. Incidentally, overaggressive removal of earwax does the same thing!

Your daughter needs to see an ear, nose and throat doctor (ENT), since most primary-care doctors have limited ability to diagnose and treat these conditions. An ENT can examine your daughter's ear under an operating microscope. (Most ENTs have this useful instrument.) While she is under the microscope, the ENT can suction pus and debris from her ear canal and can apply topical medication to the infected/inflamed skin. This approach is far more effective than a prescription for eardrops and the advice to "keep your ears dry."

If she has canal eczema, and in particular, if the only diseased tissue is the skin at the opening of the ear canal, then eardrops will probably not help, and may even make matters worse. Eardrops will wet the diseased skin, and this wetness can be counterproductive. Also, one of the most commonly prescribed eardrops contains the antibiotic neomycin. About 15 percent of the population is sensitive to neomycin; if your daughter is in this group, a neomycin-containing eardrop could make her condition much worse.

Can your daughter keep her ears dry AND teach kids how to be lifeguards? That's a tough one. The best way to keep her ears dry is to use two layers of protection: an earplug as well as a swim cap. She may have difficulty hearing her students under such circumstances.

Can this infection spread to other parts of her body? This is extremely unlikely. In medicine, we never say, "That's impossible." Any doc could imagine an unusual situation in which this infection could spread to a different part of the body ... but the emphasis here is on the word UNUSUAL.

More to the point, if left untreated, the inflamed skin may become chronically thickened. I have seen patients in whom this thickening was of a sufficient degree to cause a loss of hearing, much as an earplug causes a loss of hearing. Such patients are also in misery due to a persistent itch and, often, a low-level earache. Prompt treatment is her best defense against this condition.