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Mycoplasmas species - Overview (view source)
Revision as of 11:24, 31 July 2010
, 11:24, 31 July 2010Created page with " {{unfinished}} ===Overview=== *Pathogens belong to the ''Mycoplasma'' and ''Ureaplasma'' genera *Cause many diseases especially respiratory diseases of farm animals including ..."
{{unfinished}}
===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|neutrophils]] and macrophages and prevent phagocytosis
*Mycoplasmas induce proliferation of macrophages and [[[[Monocytes|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
===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. ovipneumoniae'' is implicated in [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of lambs|enzootic pneumonia of lambs]]
*''M. felis'' may be involved in mild [[Respiratory Bacterial Infections - Pathology#Mycoplasma felis|respiratory infection]]
*Mycoplasmas may cause [[Chronic Inflammation - Pathology#Lymphocytic Inflammation|lymphocytic chronic inflammation]] (peribronchiolar and perialveolar cuffing)
*Cause [[Peritonitis#In sheep|peritonitis in sheep]], [[Peritonitis#In goats|peritonitis in goats]] and [[Peritonitis#In pigs|peritonitis in pigs]]
==cattle==
**[[:Category:Mycoplasmas|'''''Mycoplasma spp.''''']]
***May be respinsible for some chronic cases but difficult to prove as hard to isolate
***Fibrinous polyarthritis