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Overview
- Pathogens belong to the Mycoplasma and Ureaplasma genera
- Cause many diseases including contagious bovine pleuropneumonia
- Non-pathogenic mycoplasmas present in the rumen
- Live on mucous membranes of oronasal cavity, conjunctiva and intestines
- Usually host-specific
- Limited survival in the environment
=Characteristics
- Smallest free-living prokaryotic organism
- Pleomorphic organisms
- Have no peptidoglycan cell wall
- Susceptible to dessication, heat and disinfectants
- Require enriched media containing animal protein, sterol and a source of DNA for growth
- Colonies have a fried egg appearance
- Most are facultative anaerobes
- Ureaplasmas produce urease, whereas Mycoplasmas do not metabolise urea
- Serolgy is required for specific identification
- Growth inhibition tests using specific antisera can be used as well as fluorescent antibody tests
Pathogenesis and pathogenicity
- Mycoplasmas adhere to host cells and produce toxins
- Some adhere to neutrophils and macrophages and prevent phagocytosis
- Mycoplasmas induce proliferation of macrophages and monocytes, and release of cytokines such as TNF and interleukins
- Cause damage to cilia in the respiratory tract leading to pneumonia
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- Cause peritonitis in sheep and peritonitis in goats and peritonitis in pigs
- Can be secondary to IBR
- Enzootic pneumonia of pigs caused by M. hyopneumoniae and M. hyorhinis
- Contagious bovine pleuropneumonia caused by M. mycoides
- M. bovis, M. dispar and Ureaplasma in Enzootic pneumonia of calves
- May cause lymphocytic chronic inflammation (peribronchiolar and perialveolar cuffing).
- M. felis in mild respiratory infection
- M. ovipneumoniae in enzootic pneumonia of lambs
- M. hyosynovia and M. hyorhinis produce syndrome similar to Glasser's disease with milder expression, menigitis rare, arthritis most consistent
- In cattle arthritis