Introduction
Otitis Media - Acute_Disease Background 1
Acute otitis media (AOM) is an acute suppurative infection marked by the presence of fluid in and inflammation of the middle ear.
Epidemiology
Otitis media can occur at any age but is most seen in children between the ages of 6 and 24 months. This is relatively rare during adolescence and adulthood. Males have a higher risk of developing the condition. Otitis media had the highest number of childhood cases in South Asia in 2021, while Oceania had the fewest. The highest incidence was reported in Eastern Sub-Saharan Africa, especially among children aged 12–23 months, and Central Europe had the lowest incidence.
Etiology
Otitis Media - Acute_Disease Background 2
Similar to the pediatric population, Streptococcus pneumoniae and Haemophilus influenzae are the most common causes of acute otitis media, while Moraxella catarrhalis is the third most common cause in adults. Less common pathogens include Group A beta-hemolytic streptococcus, Staphylococcus aureus, Mycoplasma pneumoniae and Chlamydia trachomatis. Viral pathogens causing upper respiratory tract infection (URTI), such as rhinovirus, respiratory syncytial virus, parainfluenza, coronavirus, and adenovirus, may also predispose a patient to develop acute otitis media.
Pathophysiology
Otitis media usually begins after a viral upper respiratory infection causes inflammation of the nose, nasopharynx, middle ear, and Eustachian tube. Swelling blocks the Eustachian tube, reducing ventilation and creating negative pressure in the middle ear. This leads to fluid and mucus buildup, allowing bacteria or viruses to grow and produce pus, resulting in a bulging and reddened tympanic membrane.
Risk Factors
Eustachian tube dysfunction is the most important risk factor. This causes a relative negative pressure in the middle ear space, leading to a lack of aeration and accumulation of fluid, which provides an environment conducive to acute otitis media development. Eustachian tube obstruction (eg malignancy or post-radiation fibrosis), immune dysfunction secondary to congenital or acquired immunologic deficiencies, concomitant malignancy, and use of immunosuppressive drugs may also increase the risk for acute otitis media and its complications. Other risk factors include family history of acute otitis media, seasonal variation, gastroesophageal reflux, and exposure to tobacco smoke.