Panel discussion: pathogenesis of otitis media. Bacteriology and immunology.

Three features of otitis media with effusion (OME) are important in understanding its pathogenesis: 1. it is most common among children, when the eustachian tube is poorly developed; 2. it is most common during the winter months, when the common cold is prevalent; and 3. bacteria are found in a large number of middle ear effusions from OME patients. Although middle ear effusions are conventionally thought to be sterile, numerous recent investigations favor a bacterial pathogenesis of OME. Four possibilities can be considered: 1. bacteria are modified by antibiotics or antibodies, causing a lingering inflammation; 2. early antibiotic treatment may interfere with the development of local immunity; 3. bacterial antigen trapped in the middle ear causes immune injury leading to OME; and 4. bacterial endotoxin and inflammatory mediators cause middle ear effusions.