Middle Ear Infection - From Merck Manual

Acute Middle Ear Infection

Middle ear infections are extremely common between the ages of 3 months and 3 years and often accompany the common cold. Young children are susceptible to middle ear infections for several reasons. The eustachian tube, which balances pressure within the ear, connects the middle ear with the nasal passages (see Middle and Inner Ear Disorders:Barotrauma). In older children and adults, the tube is more vertical, wider, and fairly rigid, and secretions that pass into it from the nasal passages drain easily. But in younger children, the eustachian tube is more horizontal, narrower, and less rigid. The tube is more likely to become obstructed by secretions and to collapse, trapping those secretions in or close to the middle ear and impairing middle ear ventilation. Any viruses or bacteria in the secretions then multiply, causing infection. Viruses and bacteria can move back up the short eustachian tube of infants, causing middle ear infections.
Besides differences in anatomy of the ear, infants at about the age of 6 months become more susceptible to infection because they lose protection from their mother's antibodies, which they received through the placenta before birth. Breastfeeding appears to partially protect children from ear infections because the mother's antibodies are contained in breast milk. Children also become more sociable around this time and may develop viral infections by touching other children and objects and putting their fingers in their mouth and nose; these infections may in turn lead to middle ear infections. Exposure to cigarette smoke further increases the risk for middle ear infections, as does the use of a pacifier, both of which may impair the function of the eustachian tube and affect middle ear ventilation. Attendance at childcare centers increases the risk of exposure to the common cold and hence to otitis media.
Middle ear infections can resolve relatively quickly (acute), or they can recur or persist over a long time (chronic).
Acute Middle Ear Infection
Acute middle ear infection (also called acute otitis media (see Middle and Inner Ear Disorders: Otitis Media (Acute)) is most often caused by the same viruses that cause the common cold. Acute infection may also be caused by bacteria found in the mouth and nose, such as Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. An infection initially caused by a virus sometimes leads to a bacterial infection.
Infants with acute middle ear infections have fever, crying or irritability that sometimes cannot be explained, and disturbances in sleep. They may also have a runny nose, cough, vomiting, and diarrhea. Infants and children who cannot fully communicate may pull at their ears. Older children are usually able to tell parents that their ear hurts or that they cannot hear well.
Commonly, fluid may accumulate behind the eardrum and persist after the acute infection has resolved (serous otitis media). Rarely, acute middle ear infection leads to more serious complications. Rupture of the eardrum can cause drainage of blood or fluid from the ear. Infection of the bone surrounding the ear (mastoiditis) can cause pain; infection of the inner ear (labyrinthitis) can cause dizziness and deafness; and infection of the tissues surrounding the brain (meningitis) or brain abscesses (collections of pus) can cause seizures and other neurologic problems. Recurring infections can promote growth of skinlike tissue through the eardrum (cholesteatoma). Cholesteatoma can damage the bones of the middle ear and cause hearing loss.
Doctors diagnose acute middle ear infections by looking for bulging and redness of the eardrum with an otoscope. They may need to clean wax from the ear first so they can see more clearly. Doctors may use a rubber bulb and tube attached to the otoscope to squeeze air into the ear to see if the eardrum moves. If the eardrum does not move or moves only slightly, then infection may be present.
Acetaminophen or ibuprofen is effective for fever and pain. Doctors used to give antibiotics to all children with acute middle ear infections. However, they now realize that many acute middle ear infections improve without antibiotics. Thus, many doctors use antibiotics (such as amoxicillin with or without clavulanate, or trimethoprim with sulfamethoxazole ) only when the child does not improve after a brief period of time or if there are signs that the infection is not getting better.

Chronic Middle Ear Infection
Chronic middle ear infection occurs as a result of repeated acute infection or when recurring infections damage the eardrum or lead to formation of a cholesteatoma, which in turn promotes more infection. Chronic ear infections are more likely among children who are exposed to cigarette smoke, use pacifiers, and attend group day care centers. For children with chronic ear infections, doctors may recommend daily antibiotics for several months. If infection persists or recurs despite the use of antibiotics, or if chronic infections have led to eardrum damage or formation of cholesteatoma, doctors may recommend ventilating (tympanostomy) tubes, eardrum repair, or surgical removal of the cholesteatoma.