The microbiologic and immunologic basis for recurrent otitis media in children

Otitis media is very common in children. A subpopulation of children. repre senting 5-10% of the general population, are otitis prone and they experien ce 4 or more episodes of acute otitis media (AOM) in the first year of life . Nasopharyngeal colonization with the three major middle ear pathogens, S. pneumoniae, nontypeable H. influenzae and M. catarrhalis is frequent in ot itis prone children and is directly related to the frequency of AOM. Coloni zation stimulates the production of mucosal as well as serum antibodies to the pathogens. Specific IgA mucosal antibody limits the duration and freque ncy of colonization. Serum Ige antibody protects children against tile deve lopment of otitis media but does not affect colonization. Antibody detected in the middle ear often reflects passive transfer from serum rather than l ocal production. Antibody responses to the three pathogens following AOM ar e generally reduced in the first 2 years of life and rise rapidly thereafte r. There are many different strains of Streptococcus pneumoniae, Haemophilu s influenzae and Moraxella catarrhalis. Among the different strains, there are heterologous surface antigens and some conserved antigens. Conserved an tigens induce broadly protective antibodies while strain specific antigens induce limited protection. Although otitis prone children may display strai n specific immunity, they often fail to develop a broadly protective antibo dy response. This subtle immunologic defect makes them susceptible to recur rent and persistent otitis media. Conclusions Otitis media is common. Otitis prone children appear to display a subtle immunologic abnormality that predisposes them to recurrent infect ions. Recent advances in vaccine development may reduce the frequency of ot itis media in the general population but the impact on otitis prone childre n remains unknown.