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Biochemical and immunochemical characteristics of middle ear effusions in relation to bacteriological findings
Abstract:
Experimental otitis media was produced in chinchillas by eustachian tube obstruction or pneumococcal infection. Sequential changes in the histology of the middle ear mucosa and enzyme profile of the middle ear effusions (MEE) were studied. In serous otitis media (SOM) which followed tubal obstruction, the subepithelial space was widened by edema and capillary dilatation, and the middle ear space was filled with serous fluid. Slight hyperplasia of epithelial cells was also observed. The subepithelial space remained widened with mild fibrous change and capillary dilatation, and slight hyperplasia of epithelial cells persisted 42 days after obstruction. In purulent otitis media (POM), which followed inoculation of pneumococci into the middle ears, metaplasia of the epithelial layer from flat to columnar cells was observed. The subepithelial space was widened with loose fibrous connective tissue proliferation, vascular dilatation and inflammatory cell infiltration. Both lactate dehydrogenase (LDH) and lysozyme levels in MEE were higher in the POM group than in the SOM group. When bacterial enzymes, hyaluronidase and lipase activity were measured in MEE and plotted together with the percentage of positive culture of the MEE at different times after the experimental infection, the enzyme activities decreased with the clearing of bacteria and along with the resorption of inflammatory changes of middle ear mucosa evidenced by histology. In human MEE studies, immunoglobulins (IgG, IgA, IgM) of MEE were higher than in serum except IgM in serous MEE. The IgG content of MEE in the culture-negative group was higher than in the culture-positive group. Possible mechanisms for this difference were discussed.
Insights
This study investigated otitis media in chinchillas, comparing serous and purulent forms. Enzyme and immunoglobulin levels in middle ear effusions (MEE) differed between types, offering insights into disease mechanisms.
Area of Science:
- Otolaryngology
- Microbiology
- Immunology
Background:
- Otitis media (OM) is a common middle ear infection.
- Understanding the differences between serous (SOM) and purulent (POM) OM is crucial for effective treatment.
- Histological and biochemical changes in the middle ear mucosa and effusions are key indicators of OM progression.
Purpose of the Study:
- To investigate the sequential histological changes in middle ear mucosa during experimental otitis media.
- To analyze the enzyme profiles of middle ear effusions (MEE) in SOM and POM.
- To compare immunoglobulin levels in human MEE with serum.
Main Methods:
- Experimental otitis media was induced in chinchillas via eustachian tube obstruction (SOM) or pneumococcal infection (POM).
- Histological examination of middle ear mucosa was performed sequentially.
- Enzyme (LDH, lysozyme, hyaluronidase, lipase) and immunoglobulin (IgG, IgA, IgM) levels in MEE were measured.
Main Results:
- SOM showed mucosal edema and serous fluid, while POM exhibited epithelial metaplasia and inflammatory infiltration.
- Lactate dehydrogenase (LDH) and lysozyme levels were higher in POM MEE.
- Bacterial enzyme activity in MEE correlated inversely with bacterial clearance and histological resolution.
- Human MEE showed higher immunoglobulins (IgG, IgA) than serum, with higher IgG in culture-negative cases.
Conclusions:
- Histological and biochemical profiles differ significantly between experimental SOM and POM.
- Enzyme activity in MEE reflects bacterial load and inflammatory status.
- Immunoglobulin levels in MEE, particularly IgG, may play a role in resolving middle ear infections.