Ear infections result from infection and fluid retention the ear. When ear infections occur in the middle ear, the region of the ear just behind the ear drum, they are known as acute otitis media. Ear infections can also occur in the external ear, the area outside of the ear drum, including the ear canal. Infections of the outer ear are known as otitis externa. Ear infections are very common in children, but adults are sometimes afflicted as well. There are a few different potential causes of ear infections in adults.
Bacterial Infections
Bacterial infections are a common cause of ear infections in adults, reports the National Institute on Deafness and Other Communication Disorders. Strep throat, which is caused by the bacteria Streptococcus pneumoniae, often begins in the upper respiratory tract. If the infection grows particularly severe, the bacteria may invade the middle ear as well, causing an ear infection. Other species of bacteria that may cause ear infections include Haemophilus influenzae and Moraxella catarrhalis. The infection causes fluid to accumulate inside the middle ear, resulting in pressure and pain.
Viral Infection
Ear infections can also result from viral infections, such as a cold or sinus infection. However, the virus itself does not usually cause the infection. Instead, the viral infection weakens the immune system and creates conditions that favor bacteria growing in the middle ear as a secondary infection, explains the National Institute on Deafness and Other Communication Disorders. The viruses that often cause ear infections include influenza viruses, adenoviruses, rhinoviruses and respiratory syncytial viruses.
Allergies or Irritants
Another cause of ear infections is blockage of the eustachian tubes, the narrow tubes that connect the middle ear to the back of the throat. Congestion that occurs from allergies or exposure to tobacco smoke and other irritants can cause the sinuses to swell and block the eustachian tubes. This blockage prevents fluids from draining normally from the inner ear, which can create conditions favorable for bacterial and viral growth in the middle ear, Medline Plus explains.
Infected Adenoid Glands
The adenoid glands sit at the top of the throat, close to the eustachian tubes. These gland are involved in fighting infections in the body. While fighting infection, the adenoids may become swollen, which can block the eustachian tubes and cause infection. Alternatively, the adenoids may become infected themselves with the germ they are fighting, and the germ may spread to the inner ear and cause an ear infection, reports the Mayo Clinic.
Swimmer's Ear
Swimmer's ear, as otitis externa is commonly called, occurs when bacteria infect the outer ear instead of the middle ear. The bacteria are often found in contaminated water, and if the water stays in contact with the ear canal for an extended period of time, it can cause an infection of the outer ear. Pseudomonas aeruginosa is the bacteria that causes most cases of swimmer's ear.
References
- National Institute on Deafness and Other Communication Disorders: Ear Infections in Children
- Medline Plus: Ear Infection - Acute
- Centers for Disease Control and Prevention: Ear Infections
- MayoClinic.com: Ear Infection, Middle Ear
- Centers for Disease Control and Prevention: Swimmer's Ear Otitis Externa
