Middle ear and eustachian tube

This chapter reviews the data regarding the mucosal immune system equipped in the middle ear, and microbiologic as well as immunologic aspects of otitis media (OM). The chapter also discusses the efficacy of mucosal vaccines for OM. Otitis media (OM), such as acute otitis media (AOM) and otitis media with effusion (OME), is one of the most prevalent infectious diseases in children and accounts for a significant medical cost. Streptococcus pneumoniae, nontypeable Haemophilus influenza (NTHi), and Moraxella catarrhalis-are the most common causative bacteria for AOM as well as OME. Because these pathogens ascend into the middle ear from the nasopharynx through the eustachian tube, nasopharyngeal colonization with these bacteria is considered the prerequisite for OM. Effective vaccines for OM must possess surface epitopes of microbial antigens that are common among strains and able to elicit protective antibodies. Because NTHi lack capsular polysaccharide, antigenic determinants of NTHi are outer membrane proteins. Among the outer membrane proteins, P6 is a highly conserved peptidoglycan- associated lipoprotein present in all strains of NTHi. Experimental findings suggest that intranasal immunization is an effective vaccination regimen for the induction of antigen-specific mucosal immune responses in the upper respiratory tract.