The most common ear infections are middle-ear infections (otitis media). The middle ear is located behind the eardrum and connected to the throat by the eustachian tube. Bacteria may travel up to the middle ear from an infection in the throat, or they may enter through a hole in the eardrum. Acute middle-ear infections are accompanied by intense, stabbing pains. Antibiotics such as erythromycin and ampicillin are used to clear up such disorders.
If untreated, middle-ear infections may become chronic. Such infections may also be associated with allergies, tuberculosis, measles, and other diseases. Their primary symptom is chronic drainage, or a "running ear," which usually is painless but may be accompanied by a ringing sensation (tinnitus) in the ear. A draining ear is a warning to consult a physician promptly. It must be kept dry and clear, and it is especially dangerous for the patient to go swimming. Chronic ear infections are treatable by antibiotics.
The primary danger in middle-ear infections is that complications may occur. Pus trapped in the middle ear may enter the mastoid process, the bony area that can be felt behind the external ear. From there it may spread to the inner ear, causing some degree of deafness. It may even reach the membranes that cover the brain, causing meningitis and possible death.
Young children, with shorter and straighter eustachian tubes than adults, are especially prone to middle-ear infections. The tendency is also apparently inherited. Fluid buildup in the middle ear is often treated by a small eardrum incision (myringotomy) to permit draining; the incision soon closes. Many children in the United States also have tubes inserted through such incisions to permit draining. The tubes usually stay in place for a few months, during which time the ears must be kept out of water. Some physicians urge caution in resorting to this technique, however, because it can lead to complications. Researchers have also linked recurrent middle-ear infections in young children to food allergies.