Difference between revisions of "Mycoplasmas"
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| + | ===Overview=== | ||
| + | |||
| + | *Pathogens belong to the ''Mycoplasma'' and ''Ureaplasma'' genera | ||
| + | *Cause many diseases especially respiratory diseases of farm animals including contagious bovine pleuropneumonia | ||
| + | *Can be involved in mastitis and conjunctivitis in cattle | ||
| + | *Implicated in respiratory and urinary tract diseases in dogs and cats | ||
| + | *Non-pathogenic mycoplasmas present in the rumen | ||
| + | *Live on mucous membranes of oronasal cavity, conjunctiva and intestines | ||
| + | *Stress factors and concurrent disease may predispose to tissue invasion | ||
| + | *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 | ||
| + | |||
| + | |||
| + | ===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 | ||
| + | *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 | ||
| + | |||
| + | |||
| + | ===Clinical infections=== | ||
| + | |||
| + | * | ||
| + | |||
| + | |||
| + | *Cause [[Peritoneal Cavity Inflammatory - Pathology#In sheep|peritonitis in sheep]] and [[Peritoneal Cavity Inflammatory - Pathology#In goats|peritonitis in goats]] and [[Peritoneal Cavity Inflammatory - Pathology#In pigs|peritonitis in pigs]] | ||
| + | *Can be secondary to [[Respiratory Viral Infections - Pathology#In Cattle|IBR]] | ||
| + | *[[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of pigs|Enzootic pneumonia of pigs]] caused by ''M. hyopneumoniae'' and ''M. hyorhinis'' | ||
| + | *[[Respiratory Bacterial Infections - Pathology#Contagious bovine pleuropneumonia (CBPP)|Contagious bovine pleuropneumonia]] caused by ''M. mycoides'' | ||
| + | *''M. bovis'', ''M. dispar'' and ''Ureaplasma'' in [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]] | ||
| + | * May cause [[General Pathology - Chronic Inflammation#Lymphocytic Inflammation|lymphocytic chronic inflammation]] (peribronchiolar and perialveolar cuffing). | ||
| + | *''M. felis'' in mild [[Respiratory Bacterial Infections - Pathology#Mycoplasma felis|respiratory infection]] | ||
| + | *''M. ovipneumoniae'' in [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of lambs|enzootic pneumonia of lambs]] | ||
| + | *''M. hyosynovia'' and ''M. hyorhinis'' produce syndrome similar to [[Haemophilus species|Glasser's disease]] with milder expression, menigitis rare, [[Joints Inflammatory - Pathology#In Pigs|arthritis]] most consistent | ||
| + | *In cattle [[Joints Inflammatory - Pathology#In Cattle|arthritis]] | ||
Revision as of 11:25, 30 December 2008
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Overview
- Pathogens belong to the Mycoplasma and Ureaplasma genera
- Cause many diseases especially respiratory diseases of farm animals including contagious bovine pleuropneumonia
- Can be involved in mastitis and conjunctivitis in cattle
- Implicated in respiratory and urinary tract diseases in dogs and cats
- Non-pathogenic mycoplasmas present in the rumen
- Live on mucous membranes of oronasal cavity, conjunctiva and intestines
- Stress factors and concurrent disease may predispose to tissue invasion
- 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
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
- 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
Clinical infections
- 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