Why do adults get ear infections?

A Normal Part of Aging? It uses the same kinds of fluids and detection cells hair cells as the cochlea uses, and sends information to the brain about the attitude, rotation, and linear motion of the head. Bacteria and viruses can grow in this fluid. Common symptoms of a middle ear infection in adults are: Medical Definitions of Ear Infections Next to a cold, an ear infection is the most common childhood illness. Diseases of the Eye. When this occurs, germs have a perfect environment to flourish.