Ear Infections (Otitis Media) in Children
DescriptionAn in-depth report on the causes, diagnosis, treatment, and prevention of ear infections.
Alternative NamesOtitis Media; Tympanostomy
Acute otitis media (middle ear infection) is most often the result of a combination of factors that increase susceptibility to infections by specific organisms in the middle ear. The infection typically evolves as follows:
Of note: respiratory viruses may also contribute directly to the infection. Allergens can also produce inflammation and blockage in the Eustachian tube, which creates an environment favorable to bacteria.
Infecting Agents and Triggers
Bacteria. Certain bacteria are the primary causes of acute otitis media (AOM) and are detected in about 60% of cases. The bacteria most commonly causing ear infections are:
Of note, about 15% of these bacteria are now believed to be resistant to the first-choice antibiotics.
Viruses. Rhinovirus, a cause of the common cold, is commonly the first player in the process leading to ear infection. It is not the direct infecting agent, however. However other viruses, such as respiratory syncytial virus (RSV -- a common virus in children responsible for respiratory infections) and influenza viruses (Flu), may be actual causes of some ear infections. Evidence is increasing that such viruses may play a greater role than previously believed for either predisposing or even causing ear infections. (Such evidence rests on the significantly lower rates of ear infections in children who have been vaccinated against influenza.)
Allergies. Allergies can cause inflammation in the airways, and contribute to ear infections.
Inborn Conditions that Predispose a Child to Middle Ear Infections
Genetic Factors. Several studies suggest that multiple genetic factors may play a role in making a child susceptible to acute otitis media.
Researchers are hoping that these findings may encourage primary care physicians to closely monitor children who are offspring or siblings of individuals with a history of unusually frequent or severe upper respiratory tract infections.
Medical or Physical Conditions that Affect the Middle Ear. Any medical or physical condition that reduces the ear's defense system can increase the risk for ear infections. Children with shorter-than-normal and relatively horizontal Eustachian tubes are at particular risk for both initial and recurrent infections. Other examples include inborn structural abnormalities, such as cleft palate, or genetic conditions, such as Kartagener's syndrome, in which the cilia (hair-like structures) in the ear are immobile and cause fluid build up.
Causes of Otitis Media with Effusion (OME)
OME may occur spontaneously following an episode of acute otitis media (AOM). Susceptibility to OME may also be due to an abnormal or malfunctioning Eustachian tube that causes a negative pressure in the middle ear, which, in turn, allows fluid to leak in through capillaries. Problems in the Eustachian tube can be due to viral infections, second-hand smoke, injury, birth defects, such as cleft palate, or genetic diseases that affect the defense systems, such as Kartagener's syndrome.
Causes of Increase in Incidence of Ear Infections and Other Airway Infections and Disorders
Increased diagnosis of other disorders and infections of the upper and lower airways, such as asthma, allergies, and sinusitis, have paralleled the rise in ear infections. For example, the same bacteria are often responsible for both ear infections and sinusitis. In one study, 38% of children with ear infections also had sinusitis, and other studies have reported that nearly half of children with OME have concurrent sinusitis. These studies may have overestimated the extent of clinically important sinus disease, but nonetheless, the association is significant but causal relationships are unclear. Researchers are looking for common risk factors:
The rise in the rate of acute otitis media, then, is probably due to a combination of factors that are also responsible for the increase in these other airway problems.