Acute otitis media (AOM) is an infection of the middle ear fluid that is frequently found in young children. It is usually caused by bacterial infections but can be viral as well. Streptococcus pneumoniae, nontypeable Haemophilus influenzae, and Moraxella catarrhalis are the most common bacterial causes. Respiratory syncytial virus (RSV) and viruses that cause the common cold are the most frequent viral etiologies.

Despite universal immunization of infants with pneumococcal vaccination, S pneumoniae still accounts for the most common bacterial isolate of AOM. However, pediatric pneumococcal conjugate vaccines (containing up to 20 serotypes) have reduced AOM rates significantly. Haemophilus influenzae type b (Hib) vaccination has had only a minor impact on the incidence of AOM as nontypeable H influenzae are the second-leading bacterial cause.

AOM usually presents during or after an upper respiratory viral illness. Risk factors also include the presence of otitis media with effusion, adenoidal hypertrophy, craniofacial abnormalities, gastroesophageal reflux disease (GERD), allergic rhinitis, and rhinosinusitis.

The first stage of AOM is characterized by redness and inflammation of the tympanic membrane (TM). As pressure builds up in the middle ear, the TM bulges. An area of pressure necrosis may form, causing the eardrum to perforate and release the mucopurulent material into the external ear canal. Dramatic relief of pain and resolution of the disease usually follow shortly after discharge. This whole process can take 12 hours in virulent infections or a few days in milder infections.

• Symptoms – Children may be easily irritable with fever, earache, and a feeling of aural fullness due to inflammation. As the middle ear fills with pus, the pain increases and hearing decreases. Children with AOM may present with ear discharge (otorrhea) as the only symptom.
• Signs – Redness of TM and swelling of upper portion (pars flaccida). The TM may bulge laterally as the disease progresses, which may eventually form an area of pressure necrosis on the drum that can result in perforation.
• Patients with pressure equalization (PE) tubes may present with ear drainage and decreased hearing, often without pain.

Younger children are more susceptible to AOM because their eustachian tubes are smaller and often more horizontal than those of adults, causing fluid to build up in the middle ear. Eustachian tube dysfunction is the most common anatomic abnormality predisposing to AOM. Drainage and PE of the middle ear result in the accumulation of fluid and negative pressure in the middle ear cavity.

Children with primary humoral immune deficiency (especially immunoglobulin G [IgG] subclass deficiencies) or HIV infection are prone to recurrent AOM as part of the spectrum of clinical manifestations.

Immunocompromised Patient Considerations: AOM may present with systemic sepsis and purulent ear discharge instead of more classic signs and symptoms.

Related topic: chronic otitis media