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Intranasally inoculated Mycoplasma hyorhinis causes eustachitis in pigs
1Department of Veterinary Pathology, Tottori University, Japan. morita@agr.tottori-u.ac.jp
Veterinary Pathology
|March 31, 1999
Summary
Mycoplasma hyorhinis can cause inflammation in pig auditory tubes (eustachitis) but rarely leads to otitis media. Pasteurella multocida alone did not cause otitis in this study.
Area of Science:
- Veterinary Microbiology
- Animal Pathology
Background:
- Otitis media is a common condition in pigs, but the specific bacterial agents involved in its pathogenesis are not fully understood.
- Mycoplasma hyorhinis and Pasteurella multocida are frequently isolated from the respiratory tracts of pigs.
Purpose of the Study:
- To investigate the role of Mycoplasma hyorhinis and Pasteurella multocida in the development of otitis media in specific-pathogen-free pigs.
- To determine if coinfection with both bacteria influences disease outcome.
Main Methods:
- Specific-pathogen-free pigs were intranasally inoculated with M. hyorhinis, P. multocida, or both.
- Histological, immunohistochemical, and microbiological techniques were used to assess the auditory tubes and tympanic cavities.
Main Results:
- M. hyorhinis inoculation resulted in subacute inflammation of the auditory tubes (eustachitis) in 6/6 pigs and tympanic cavities in 2/6 pigs.
- M. hyorhinis antigens were detected in inflamed auditory tubes, and the bacteria were isolated from inflamed tympanic cavities.
- Pigs inoculated solely with P. multocida did not develop otitis, and the bacteria were not isolated from the tympanic cavity.
Conclusions:
- Mycoplasma hyorhinis is capable of causing eustachitis in pigs.
- M. hyorhinis can lead to otitis media, but it appears to be a rare outcome.
- Pasteurella multocida alone does not appear to be a primary cause of otitis media in this model.