Otitis media (infection or inflammation of the middle ear) is one of the most common infections, and acute otitis media (AOM) is among the most common diseases that lead to treatment with antibiotics . AOM primarily occurs in childhood and the medical literature overwhelmingly focuses on the presentation, course, and treatment of AOM in children. The treatment of AOM  in adults is therefore largely extrapolated from studies in children.
Life-threatening complications, though infrequent, may develop because of the proximity of the middle ear and adjacent mastoid to the middle and posterior cranial fossa and related structures. Based upon its high prevalence and potential to cause serious harm, otitis media is a public health concern.
This topic will address the etiology, diagnosis, and treatment of AOM in adults. Issues related to AOM in children are discussed separately. (See "Acute otitis media in children: Diagnosis" and "Acute otitis media in children: Epidemiology, microbiology, clinical manifestations, and complications" and "Acute otitis media in children: Treatment" and "Otitis media with effusion (serous otitis media) in children: Clinical features and diagnosis" and "Otitis media with effusion (serous otitis media) in children: Management".) Issues related to chronic otitis media in adults are also discussed separately. (See "Chronic otitis media, cholesteatoma, and mastoiditis in adults".)
CLASSIFICATION OF OTITIS MEDIA
A variety of terms, related to the area of involvement and underlying disease process, are used to categorize infectious or inflammatory conditions of the middle ear. The anatomy of the normal ear is shown in a figure (figure 1).
Acute otitis media (AOM) — Acute otitis media (AOM) is an acute illness marked by the presence of middle ear fluid and inflammation of the mucosa that lines the middle ear space (picture 1). The infection is often caused by obstruction of the eustachian tube, which results in fluid retention and suppuration of retained secretions. AOM may also be associated with purulent otorrhea if there is a ruptured tympanic membrane. AOM usually responds promptly to antimicrobial therapy.