Understanding Ear Infections -- the Basics

What Is an Ear Infection?

An ear infection, or otitis media, is the most common cause of earaches. Although this condition is a frequent cause of infant distress and is often associated with children, it can also affect adults.

The infection in the middle ear (the space behind the eardrum where tiny bones pick up vibrations and pass them along to the inner ear) very often accompanies a common cold, the flu, or other types of respiratory infections. This is because the middle ear is connected to the upper respiratory tract by a tiny channel known as the Eustachian tube. Germs that are growing in the nose or sinus cavities can climb up the Eustachian tube and enter the middle ear to start growing.

Most parents are frustratingly familiar with ear infections. Except for wellness baby visits, ear infections are the most common reason for trips to the pediatrician, accounting for approximately 30 million doctor visits a year in the U.S.

The basics on otitis media from WebMD.

Today, almost half of all antibiotic prescriptions written for children are for ear infections, and the cost of treating middle ear infections in the U.S. has been estimated at more than $2 billion a year. Untreated, ear infections can lead to more serious complications, including mastoiditis (a rare inflammation of a bone adjacent to the ear), hearing loss, perforation of the eardrum, meningitis, facial nerve paralysis, and possibly -- in adults -- Meniere's disease.

What Causes an Ear Infection?

The middle ear is a small space behind the ear drum that is supposed to be well ventilated by air that normally passes up from behind the nose, through the Eustachian tube, keeping the middle ear clean and dry. When there is not enough fresh air ventilating the middle ear, such as when the Eustachian tube is clogged or blocked, the area becomes damp, stagnant, and warm, a perfect breeding ground for germs.

In children and infants, the Eustachian tube is often too soft or immature and has a harder time staying open. Allergies, post nasal drainage, sinus infections, common cold virusesand adenoid problems can all interfere with the Eustachian tube’s ability to let air pass into the middle ear.

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When the doctor looks at the ear drum, he or she will see that it is red, often bulging, and be able to make the diagnosis of an ear infection.

For children, the most common cause of an ear infection is an upper respiratory viral infection, such as a cold or the flu. These disorders can make the Eustachian tube so swollen that air can no longer flow into the middle ear. Allergies -- to pollen, dust, animal dander, or food -- can produce the same effect as a cold or flu, as can smoke, fumes, and other environmental toxins. Bacteria can cause an ear infection directly, but usually these organisms come on the heels of a viral infection or an allergic reaction, quickly finding their way into the warm, moist environment of the middle ear. Invading bacteria can wreak major havoc, turning inflammation into infection and provoking fevers.

Among the bacteria most often found in infected middle ears are the same varieties responsible for many cases of sinusitis, pneumonia, and other respiratory infections. According to the American Academy of Otolaryngology-Head and Neck Surgery (ear, nose, and throat physicians), the conjugate pneumococcal vaccine is very effective against several strains of the most common bacteria that cause ear infections. This vaccine is routinely given to infants and toddlers to prevent meningitis, pneumonia, and blood infections. Your child’s doctor should advise you on the use of this vaccine, which may help to prevent at least some ear infections.

Ear infections occur in various patterns. A single, isolated case is called an acute ear infection (acute otitis media). If the condition clears up but comes back as many as three times in a 6-month period (or four times in a single year), the person is said to have recurrent ear infections (recurrent acute otitis media). This usually indicates the Eustachian tube isn't working well. A fluid buildup in the middle ear without infection is termed otitis media with effusion, a condition where fluid stays in the ear because it is not well ventilated, but germs have not started to grow.

In recent years, scientists have identified the characteristics of people most likely to suffer recurrent middle ear infections:

  • Males
  • Individuals with a family history of ear infections
  • Babies who are bottle-fed (breastfed babies get fewer ear infections)
  • Children in day care centers
  • People living in households with tobacco smokers
  • People with abnormalities of the palate, such as a cleft palate
  • People with poor immune systems or chronic respiratory diseases, such as cystic fibrosis and asthma
WebMD Medical Reference Reviewed by Roy Benaroch, MD on March 01, 2015

Sources

SOURCES:

American Academy of Otolaryngology - Head and Neck Surgery. 

Academy of American Family Physicians. 

Merck. 

National Institute on Deafness and Other Communication Disorders.

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