Opsonization of middle ear bacteria during chronic suppurative and secretory otitis media.

Samples of middle ear effusion were obtained from 16 patients with chronic suppurative otitis media (COM) (20 ears, age range from 1 1/12 to 69 years) and 13 patients with secretory otitis media (SOM) (15 years, age range from 8 months to 13 8/12 years). Qualitative and quantitative bacteriological analyses of the effusions were performed and the intensity of immunoglobulin G (IgG) and complement component C3b adhering to the bacteria was estimated using immunofluorescence technique. In COM effusions, S. aureus in particular was intensely opsonized, whereas Ps. aeruginosa showed minimal, if any, coating with IgG and C3b. SOM effusions exhibited extremely sparse IgG- and C3b-coated bacteria. The difference in IgG and C3b coated bacteria between COM and SOM effusions was significant (p less than 0.01). Specific (IgG) as well as non-specific (C3b) coating of the bacteria that have gained access to the middle ear cavity is of importance for the host defence.