Ear Infections – Otitis Media

Common Childhood Illness Can Be Caused by Several Types of Viruses or Bacteria

Eustachian Tube in Infant. (c) A.D.A.M.

Ear infections of the middle ear, also known as “otitis media,” are the most common illnesses in infants and small children, in whom the Eustachian tube (it connects the ear to the throat) is not fully developed. In most cases, these ear infections occur during bouts of simple colds or sore throats, during which infectious microbes find accumulated fluid within the ear.

Type of Microbe: Ear infections can be caused by several kinds of viruses and bacteria.

The most common bacteria implicated in ear infections are Streptococcus pneumoniae and Haemophilus influenzae, while Streptococcus pyogenes and Staphylococcus aureus are less common. Viruses found in infected ear fluids have included respiratory syncytial virus (RSV), influenza virus, rhinoviruses (cold viruses), enteroviruses, and others.

Many infections are not bacterial at all - and are caused by viruses - so antibiotics won't help. Vaccination against common bacterial causes of ear infections (part of a standard child's vaccination regimen) will help prevent ear infections. These vaccines do more than just prevent serious infections, like pneumonia; they also keep lots of ear infections at bay.

Depending on your child's age and symptoms, your doctor may tell you to wait and see before she or he would start antibiotics. There's a reason for this. Viral infections can get better on their own.

Antibiotics won't help. You may just be risking unnecessary antibiotics - which carry other risks like antibiotic resistance - without helping to treat the infection.

How they cause disease: An upper respiratory tract infection, such as a cold, can create excess mucous and congestion. As a result, obstruction in the Eustachian tube, which connects the ear to the throat, leads to a build-up of mucous which has nowhere to drain.

Bacteria that are already present in the middle ear begin to multiply and establish an infection. The immune response causes inflammation, during which white blood cells attack the bacteria. Dead bacteria and white cells form the yellowish-white pus that accumulates in the middle ear.

How it spreads: Bacterial ear infections generally begin with a cold or other upper respiratory tract infection. The infecting bacteria is usually already present as a "colonizer" in the respiratory tract, but kept under control by the immune system. Hence, bacterial ear infections are generally not spread from person-to-person. Like bacterial ear infections, ear infections of viral origins also begin with respiratory infections which are spread through inhalation of aerosolized droplets or person-to-person contact.

Who’s at risk? Small children between 6 and 18 months old are the most frequently infected population. By age 3, most children have had at least one ear infection. Boys are more likely to get ear infections than girls.

Symptoms: Symptoms of ear infections include ear pain, fluid in ears, fever, and impaired hearing. Since most ear infections occur in young children who may not have the verbal skills to communicate their symptoms, general signs of distress may include irritability, bouts of crying, diarrhea, and feeding problems.

Diagnosis: Ear infections are diagnosed by an ear exam. Signs of an infection include dilated blood vessels, bulging of the ear drum, and collected fluids in the middle ear. For children who are critically ill, needle aspiration of fluids in the middle ear followed by bacterial culture can be used to determine which bacteria are responsible for the infection.

Prognosis: With appropriate antibiotic treatment, more than half of infected children still have fluid remaining in the middle ear, with gradual clearing over time. Recurrent ear infections are relatively common; up to one-half of 3-year-olds have had at least 3 ear infections.

Treatment: The antibiotic Amoxicillin (a type of penicillin) is the most commonly prescribed antibiotic for ear infections, and a macrolide (erythromycin, azithromycin, or clarithromycin) can be prescribed for children with penicillin allergies. However, there is ongoing discussion within the medical field regarding the potential overuse of antibiotics for treating ear infections.

Nasal decongestants can sometimes relieve congestion associated with ear infections, but they are generally not recommended, as they are used for symptom relief only and do not help clear the infection.

Prevention: No vaccines are currently available for ear infections, but several are being developed. To prevent ear infections, reducing certain environmental exposures can help reduce the risk for ear infections. Studies have shown that children who are exposed to cigarette smoke or are cared for in daycares are more prone to having ear infections. In addition, infants who are not breast-fed are at higher risk for ear infections than those who are breast-fed, even for just 3 months.

Complications: Left untreated, ear infections can lead to serious complications, including hearing impairment and subsequent developmental delays in speech, cognitive abilities, and performance in school.

Sources

Gershon, AA, Hotez, PJ, Katz, SL. Krugman’s Infectious Diseases of Children, 11th ed. Mosby, An Affiliate of Elsevier, Inc. Philadelphia. ©2004.

Mims CA, Playfair JH, Roitt, IM, Wakelin D, Williams R, and Anderson RM. Medical Microbiology. Mosby-Year Book Europe Limited. ©1993.

Otitis Media. National Institute on Deafness and Other Communication Disorders. National Institutes of Health. Accessed March 2, 2009.
http://www.nidcd.nih.gov/health/hearing/otitism.asp

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