New views on the pathogenesis of acute otitis media and its complications.

The pathogenesis of acute otitis media is complex and multifactorial. Bacteria infecting the middle ear come from the nasopharynx via the eustachian tube. This colonization is facilitated by bacterial adherence on the pharyngeal and the eustachian tube cells. Otitis media is characterized by inflammation of the middle ear with an infiltration of the subperiosteal space by leukocytes, macrophages and mast cells. The effusion contains great amounts of inflammatory mediators (eicosanoids, cytokines, histamine). Elimination of the effusion and/or the bacteria is based on non-specific factors such as mucociliary clearance and phagocytosis, and on a specific immune response which apparently is not the same for Haemophilus influenzae and for Streptococcus pneumoniae. The main complications of acute otitis media are otitis media with effusion, mastoiditis, sensorineural hearing loss and meningitis.