Normally the eardrum is airtight and watertight. To keep pressure inside and outside the eardrum equal, we have natural "drainage" tubes (the Eustachian tubes) that connect the middle ears (the space behind the eardrum) to the back of the nose and throat. Our ears always produce small amounts of fluid; this normally drains down the Eustachian tubes, and is usually in such a small amount that we don't even notice it in the throat

Ear infections are one of the most common reasons parents take their children to the doctor. While there are different types of ear infections, the most common is called otitis media, which means an inflammation and infection of the middle ear. The middle ear is located just behind the eardrum.

Otitis media is inflammation of the middle ear. "Otitis" means inflammation of the ear, and "media" means middle. This inflammation often begins with infections that cause sore throats, colds or other respiratory problems, and spreads to the middle ear. These can be caused by viruses or bacteria, and can be acute or chronic.

The middle ear also contains the eustachian (pronounced you-STAY-shun or you-STAY-shee-un) tube, which connects the middle ear to the pharynx (pronounced FAHR-inks). The pharynx is a passageway behind the nose through which air passes into the lungs. The eustachian tube helps maintain an equal air pressure between the middle ear and the outside world.

Symptoms

In Otitis Media, inflammation occurs on that portion of the ear which is directly behind the ear drum. There is discharge of pus into the outer ear. As the condition progresses, the inner ear beomes seriously affected and hearing considerably impaired. There is suppression of middle ear through a perforation of drum. In case of children, supression may start slowly without any reason. If the suppression is left unattended it may result in deafness.
Causes
Bacteria and viruses can cause otitis media. Bacteria such as Streptococcus pneumoniae (pneumococcus), nontypable Hemophilus influenzae and Moraxella account for about 85% of cases of acute otitis media. Viruses account for the remaining 15%. Affected infants under six weeks of age tend to have infections from a variety of different bacteria in the middle ear.

Ear infections are common in infants and children in part because their eustachian tubes become clogged easily. For each ear, a eustachian tube runs from the middle ear to the back of the throat. Its purpose is to drain fluid and bacteria that normally occurs in the middle ear. If the eustachian tube becomes blocked, fluid can build up and become infected.
Diagnosis
In most cases, if someone is suffering from a cold or sore throat that suddenly gets worse, with ear pain and a fever, then the diagnosis is likely to be otitis media. It is still wise to see a doctor, as he will look into the ear with a special torch known as an otoscope, enabling him/her to see clearly if there is inflammation and/or infection.

There's no single best approach for treating all middle ear infections. In deciding how to manage your child's ear infection, a doctor will consider many factors, including:

The type and severity of the ear infection
How often your child has ear infections
How long this infection has lasted
How old your child is