Difference between revisions of "Mycoplasmas species - Overview"
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| − | + | ==Overview== | |
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| − | + | Pathogens belong to the ''Mycoplasma'' and ''Ureaplasma'' genera. They cause many diseases, especially respiratory diseases of farm animals including [[Contagious Bovine Pleuropneumonia]]. They can be involved in [[Mastitis]] and conjunctivitis in cattle and are implicated in respiratory and urinary tract diseases in dogs and cats. | |
| − | + | There are non-pathogenic mycoplasmas present in the rumen that live on the mucous membranes of the oronasal cavity, conjunctiva and intestines. Stress factors and concurrent disease may predispose to tissue invasion. ''Mycoplasmas'' are usually host-specific and have limited survival in the environment. | |
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| − | + | ==Characteristics== | |
| − | + | The ''Mycoplasmas'' are the smallest, free-living prokaryotic organisms. They are pleomorphic organisms and have no peptidoglycan cell wall. They are susceptible to dessication, heat and disinfectants and require enriched media containing animal protein, sterol and a source of DNA for growth. Their colonies have a fried egg appearance. Most are facultative anaerobes. | |
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| − | + | ==Pathogenesis and pathogenicity== | |
| − | + | ''Mycoplasmas'' adhere to host cells and produce toxins. Some adhere to [[Neutrophils|neutrophils]] and macrophages and prevent phagocytosis. ''Mycoplasmas'' induce proliferation of macrophages and [[[[Monocytes|monocytes]]]], and the release of cytokines such as TNF and interleukins. They cause damage to cilia in the respiratory tract leading to pneumonia. Molecular mimicry allows some ''mycoplasmas'' to avoid the host immune response and may initiate immune-mediated disease. | |
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| − | + | ==Diagnosis== | |
| − | + | Samples can be tested for the presence of mycoplasmas by fluorescent antibody techniques, peroxidase techniques and PCR. Biochemical profiles such as urease production can be used for identification. ''Ureaplasmas'' produce urease, whereas ''Mycoplasmas'' do not metabolise urea. Serolgy is required for specific identification including complement fixation tests, ELISA, agglutination tests and haemagglutination-inhibition tests. Growth inhibition tests using specific antisera can be used as well as fluorescent antibody tests. | |
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| − | + | ==Other mycoplasmas== | |
*''M. bovis'', ''M. dispar'' and ''Ureaplasma'' can be involved in [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]] | *''M. bovis'', ''M. dispar'' and ''Ureaplasma'' can be involved in [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]] | ||
Revision as of 11:32, 31 July 2010
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This article is still under construction. |
Overview
Pathogens belong to the Mycoplasma and Ureaplasma genera. They cause many diseases, especially respiratory diseases of farm animals including Contagious Bovine Pleuropneumonia. They can be involved in Mastitis and conjunctivitis in cattle and are implicated in respiratory and urinary tract diseases in dogs and cats. There are non-pathogenic mycoplasmas present in the rumen that live on the mucous membranes of the oronasal cavity, conjunctiva and intestines. Stress factors and concurrent disease may predispose to tissue invasion. Mycoplasmas are usually host-specific and have limited survival in the environment.
Characteristics
The Mycoplasmas are the smallest, free-living prokaryotic organisms. They are pleomorphic organisms and have no peptidoglycan cell wall. They are susceptible to dessication, heat and disinfectants and require enriched media containing animal protein, sterol and a source of DNA for growth. Their colonies have a fried egg appearance. Most are facultative anaerobes.
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 the release of cytokines such as TNF and interleukins. They cause damage to cilia in the respiratory tract leading to pneumonia. Molecular mimicry allows some mycoplasmas to avoid the host immune response and may initiate immune-mediated disease.
Diagnosis
Samples can be tested for the presence of mycoplasmas by fluorescent antibody techniques, peroxidase techniques and PCR. Biochemical profiles such as urease production can be used for identification. Ureaplasmas produce urease, whereas Mycoplasmas do not metabolise urea. Serolgy is required for specific identification including complement fixation tests, ELISA, agglutination tests and haemagglutination-inhibition tests. Growth inhibition tests using specific antisera can be used as well as fluorescent antibody tests.
Other mycoplasmas
- M. bovis, M. dispar and Ureaplasma can be involved in Enzootic pneumonia of calves
- M. ovipneumoniae is implicated in enzootic pneumonia of lambs
- M. felis may be involved in mild respiratory infection
- Mycoplasmas may cause lymphocytic chronic inflammation (peribronchiolar and perialveolar cuffing)
- Cause peritonitis in sheep, peritonitis in goats and peritonitis in pigs
cattle
- Mycoplasma spp.
- May be respinsible for some chronic cases but difficult to prove as hard to isolate
- Fibrinous polyarthritis
- Mycoplasma spp.