From 14 chronic middle ear effusions (MEEs), 17 strains of coagulase-negative staphylococci (CS) were isolated. We then used an ELISA method to determine the antibody titers against these microorganisms in the corresponding effusion fluids and the blood sera of the patients and compared them to the antibody titers against a group of standard CS. In most cases, no specific immune response could be detected against the infecting CS in either the effusion fluids or in the sera. Our results can be explained by the inability of most CS strains to provoke a specific immune response in chronically inflamed middle ears due to their inhibition by non-specific antibodies, which reach the middle ear cavity by plasma leakage. The non-specific antibody titer against Staphylococcus hominis, however, seems to be much lower than against the other CS species. We found a high specific antibody titer against the infecting CS in the effusion fluid of a single case, but not in the serum. This finding supports the hypothesis that the middle ear mucosa has the ability to produce autonomous, local antibodies which are independent of a systemic immune response.
Middle ear Antibody titers Otitis media with effusion Coagulase-negative staphylococci