Otitis media causes
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hardik Patel, M.D.
Overview
For each ear, a eustachian tube runs from the middle ear to the back of the throat. This tube drains fluid that is normally made in the middle ear. If the eustachian tube becomes blocked, fluid can build up. When this happens, germs such as bacteria and viruses can multiply and cause an infection. Ear infections are common in infants and children, in part because the eustachian tubes become easily clogged. Ear infections may also occur in adults, although they are less common than in children.
Causes
Streptococcus pneumoniae and nontypable Haemophilus influenzae are the most common bacterial causes of otitis media. Tubal dysfunction leads to the ineffective clearing of bacteria from the middle ear. In older adolescents and young adults, the most common cause of ear infections during their childhoods was Haemophilus influenzae. The role of the anti-H. influenzae vaccine that children are regularly given in changing patterns of ear infections is unclear, as this vaccine is active only against strains of serotype b, which rarely cause otitis media.
As well as being caused by Streptococcus pneumoniae and Haemophilus influenzae it can also be caused by the common cold. Colds indirectly cause many cases of otitis media by damaging the normal defenses of the epithelial cells in the upper respiratory tract.
Another common culprit of otitis media includes Moraxella catarrhalis, a gram-negative, aerobic, oxidase positive diplococcus. Less commonly otitis media can be caused by Mycobacterium tuberculosis.
Anything that causes the eustachian tubes to become swollen or blocked causes more fluids to build up in the middle ear behind the eardrum. These causes include:
- Allergies
- Colds and sinus infections
- Excess mucus and saliva produced during teething
- Infected or overgrown adenoids
- Tobacco smoke or other irritants
Ear infections are also more likely if a child spends a lot of time drinking from a sippy cup or bottle while lying on his or her back. Contrary to popular opinion, getting water in the ears will not cause an acute ear infection, unless the eardrum has a hole from a previous episode. Ear infections occur most often in the winter. You cannot catch an ear infection from someone else, but a cold may spread among children and cause some of them to get ear infections.