Secretory IgA- and IgG-coated bacteria in chronically discharging ears.

SIgA- and IgG-coated bacteria obtained from 17 discharging middle ears (14 patients, 9 male, 5 female, age range from 1 to 79 years) were evaluated using an immunofluorescence assay. Simultaneously, quantitative and qualitative bacteriological analyses of the middle ear effusions (MEEs) were performed. MEEs containing Staphylococcus aureus harboured bacteria which were intensely coated with both SIgA and IgG antibodies. In contrast, MEEs containing Pseudomonas aeruginosa displayed minimal, if any, SIgA- and IgG-coated bacteria. Two young patients harboured bacteria (Haemophilus influenzae and S. aureus/Streptococcus pneumoniae, respectively) which were heavily coated with IgG, but not with SIgA. Immunoglobulin-coating of bacteria involved in otitis media is of the utmost importance in eradication of the infection.