Causes and Risk Factors of Middle Ear Infection

Show Article Table of Contents

While children are at the greatest risk of middle ear infections (otitis media), adults can also experience them. Blockage of the eustachian tube is the usual cause, leading to bacterial or viral infection in the middle ear. This can be due to anatomic factors and triggered by colds, allergies, and other respiratory infections.

middle ear infection causes
© Verywell, 2018 

Common Causes

The most common cause of otitis media is eustachian tube blockage. The eustachian tube is a passageway from the back of your nose and throat to your middle ear, which is the part of your ear that is behind the eardrum. Your eustachian tube regulates air pressure in the middle ear and drains secretions from it. If the eustachian tube is blocked, fluid or bacteria become trapped inside the ear and cause an infection.

Eustachian tube dysfunction is more common in children because the passage is narrower and it doesn't have the slant it does in adults, so it doesn't drain as well. For some, the poor tubal function can persist into adulthood and is the main cause of middle ear infections in adults.

Adenoids, located in the back of the nose near the opening of the eustachian tubes, can block the tubes if they become swollen or inflamed. This is more of a problem in children because their adenoids are relatively larger.

Both bacteria and viruses can produce an ear infection once trapped in the middle ear. The most common bacteria involved are Streptococcus pneumoniae and Haemophilus influenzae, with less common infections owed to Streptococcus pyogenes and Staphylococcus aureus. Viruses include cold viruses (rhinoviruses), respiratory syncytial virus (RSV), influenza virus, and enteroviruses.

Standard childhood vaccinations protect against some of these agents and help prevent ear infections.

Common Risk Factors

The risk factors for blocked eustachian tubes and middle ear infections include:

  • Age: Babies and toddlers between the ages of 6 months and 2 years are at the greatest risk for ear infections. This is because of the anatomy of the eustachian tube and the fact that their immune systems are still developing.
  • Upper respiratory tract infections: Children are more at risk of catching colds because their immune systems have had less exposure to viruses (and, therefore, haven't developed defenses against them). That said, this is also a risk factor for adults.
  • Allergic rhinitis: Seasonal hay fever, allergies to specific allergens, or chronic allergies can lead to ear infections in both children and adults. Allergies cause more secretions, and the inflammatory compounds released also irritate and damage the lining of the ears. Controlling allergies can help reduce the risk. However, antihistamines and decongestants have not been found to be of benefit in preventing otitis media in children.
  • Malformation of the eustachian tube or craniofacial (head/face) disorders that cause palatal muscle weakness like cleft palate
  • Mucosal disease of the ears, nose, or throat, such as sinusitis
  • Enlarged structures in your ears, nose, or throat like the adenoidsturbinates, or nasal polyps
  • A weakened immune system
  • A family history of susceptibility to ear infections

Lifestyle Risk Factors

There are other risk factors you can modify, and these suggestions can help you do just that. 

Avoiding getting colds and other upper respiratory infections are key to reducing the risk of middle ear infection. Wash your hands often and teach your children to cover coughs and sneezes to avoid spreading germs. For children with recurrent ear infections, you may want to consider reducing the time they spend in group child care settings, if possible.

Consider these additional steps to address risk factors for a middle ear infection that are within your control:

Babies and Children

  • If you choose to breastfeed, consider doing so for at least six months so your baby benefits from the antibodies in your breast milk.
  • Keep your baby in an upright position when bottle feeding. Don't prop up a bottle while your child is lying flat.
  • Reduce the use of a pacifier once your baby is 6 months old, as some studies have found this increases the risk of ear infections.
  • Avoid exposing babies and children to cigarette smoke; it impairs the function of the eustachian tubes and increases the risk of middle ear infections.
  • Get the Prevnar 13 vaccine, which protects against ear infections by 13 subtypes of Streptococcus bacteria, and the annual flu shot.
  • Leave any removal of earwax to a pediatrician. Cotton swabs and other objects can clog and irritate ear canals, leading to infection.

Adults

  • Stop smoking and avoid secondhand cigarette smoke.
  • Take a decongestant when you have a cold or before getting on an airplane so your eustachian tubes are less likely to be congested and you will be able to relieve the change in air pressure during ascent and descent.
  • Avoid trying to clean your earwax using cotton swabs or other objects.

Like many infections, not receiving treatment for a middle ear infection can result in complications, including hearing loss in any age group and delays in speech and language development for children. There is also the risk of the infection spreading to the mastoid bone and other tissues. Seeking care from your doctor and following treatment recommendations can help avoid these complications.

Was this page helpful?
Article Sources