Difference between revisions of "Mycoplasmas"

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#REDIRECT[[:Category:Mycoplasmas]]
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|linktext =BACTERIA
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<br>
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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
 +
 
 +
 
 +
===[[Respiratory Bacterial Infections - Pathology#Contagious bovine pleuropneumonia (CBPP)|Contagious bovine pleuropneumonia]]===
 +
 
 +
*[[Respiratory Bacterial Infections - Pathology#Contagious bovine pleuropneumonia (CBPP)|Contagious bovine pleuropneumonia]] is caused by ''M. mycoides'' subsp. ''mycoides''
 +
*A severe contagious disease of cattle
 +
*Endemic in Africa, the Middle East and Asia
 +
*Aerosol transmission by close contact with clinically or subclinically affected animals
 +
*Severity depends on strain and host susceptibility
 +
*Slow spread of infection
 +
*50% morbidity; mortality rate high in severe outbreaks
 +
 
 +
*Clinical signs
 +
**Acute onset fever, anorexia, depression, lowered milk yield, hyperpnoea, coughing and a mucopurulent nasal discharge
 +
**Dyspnoea occurs with abducted elbows and extended necks and an expiratory grunt
 +
**Can be fatal within 1-3 weeks
 +
**Calves may suffer from [[Joints Inflammatory - Pathology#In Cattle|arthritis]], synovitis and endocarditis
 +
 
 +
*Gross pathology
 +
**Marbled appearance to lungs with consolidated grey and red lobules separated by emphysematous areas
 +
**Serofibrinous pleural fluid
 +
**Necrotic foci surrounded by fibrous capsules in chronic cases act as source of infection
 +
 
 +
*Diagnosis
 +
**Clinical signs and post-mortem appearance
 +
**PCR on pleural fluid, lung tissue, regional lymph nodes or bronchoalveolar lavage fluid
 +
**Fluorescent antibody test
 +
**Serological tests such as serum agglutination, haemagglutination, complement fixation, ELISA
 +
 
 +
*Treatment and control
 +
**Slaughter of affected cattle in counries where the disease is exotic
 +
**Movement restrictions, quaranteen and slaughter of carrier animals in endemic countries
 +
**Vaccination in endemic regions
 +
 
 +
 
 +
===''Mycoplasma bovis''===
 +
 
 +
*Causes severe pneumonia in calves as a primary pathogen
 +
*Can occur secondarily to ''Pasteurella'' and ''Mannheimia'' and [[Respiratory Viral Infections - Pathology#In Cattle|IBR]]
 +
*Associated with [[Joints Inflammatory - Pathology#In Cattle|arthritis]] and mastitis
 +
*Mastitis associated with a severe drop in milk yield and a purulent discharge
 +
 
 +
 
 +
===Contagious agalactia of sheep and goats===
 +
 
 +
*Severe febrile disease of sheep and goats in parts of Europe, Africa, Asia
 +
*Caused by ''M. agalactiae''
 +
*Mastitis, arthritis and conjunctivitis following parturition
 +
*Causes abortion
 +
*Fatal pneumonia in young animals
 +
*Shed in milk; localised in supramammary lymph nodes
 +
*Inactivated, attenuated vaccines available
 +
 
 +
 
 +
===Contagious caprine pleuropneumonia===
 +
 
 +
*Caused by ''M. capricolum'' subsp. ''capricolum'; occasionally ''M. mycoides'' subsp. ''capri'' or ''M. mycoides'' subsp. ''mcoides''
 +
*Occurs in Africa and Turkey
 +
*Pneumonia, fibrinous pleurisy, pleural exudate, consolidated and emphysematous lungs
 +
*Aerosol transmission; highly contagious
 +
*Identified by growth inhibition disc tests
 +
*Inactivated vaccines available
 +
 
 +
 
 +
===Enzootic pneumonia of pigs===
 +
 
 +
*Caused by ''M. hyopneumonia''
 +
 
 +
 
 +
 
 +
*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]]
 +
*[[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of pigs|Enzootic pneumonia of pigs]] caused by ''M. hyopneumoniae'' and ''M. hyorhinis''
 +
*''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

Revision as of 12:08, 30 December 2008

 This article has been peer reviewed but is awaiting expert review. If you would like to help with this, please see more information about expert reviewing.


Infectious agents and parasitesWikiBugs Banner.png
BACTERIA



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


Contagious bovine pleuropneumonia

  • Contagious bovine pleuropneumonia is caused by M. mycoides subsp. mycoides
  • A severe contagious disease of cattle
  • Endemic in Africa, the Middle East and Asia
  • Aerosol transmission by close contact with clinically or subclinically affected animals
  • Severity depends on strain and host susceptibility
  • Slow spread of infection
  • 50% morbidity; mortality rate high in severe outbreaks
  • Clinical signs
    • Acute onset fever, anorexia, depression, lowered milk yield, hyperpnoea, coughing and a mucopurulent nasal discharge
    • Dyspnoea occurs with abducted elbows and extended necks and an expiratory grunt
    • Can be fatal within 1-3 weeks
    • Calves may suffer from arthritis, synovitis and endocarditis
  • Gross pathology
    • Marbled appearance to lungs with consolidated grey and red lobules separated by emphysematous areas
    • Serofibrinous pleural fluid
    • Necrotic foci surrounded by fibrous capsules in chronic cases act as source of infection
  • Diagnosis
    • Clinical signs and post-mortem appearance
    • PCR on pleural fluid, lung tissue, regional lymph nodes or bronchoalveolar lavage fluid
    • Fluorescent antibody test
    • Serological tests such as serum agglutination, haemagglutination, complement fixation, ELISA
  • Treatment and control
    • Slaughter of affected cattle in counries where the disease is exotic
    • Movement restrictions, quaranteen and slaughter of carrier animals in endemic countries
    • Vaccination in endemic regions


Mycoplasma bovis

  • Causes severe pneumonia in calves as a primary pathogen
  • Can occur secondarily to Pasteurella and Mannheimia and IBR
  • Associated with arthritis and mastitis
  • Mastitis associated with a severe drop in milk yield and a purulent discharge


Contagious agalactia of sheep and goats

  • Severe febrile disease of sheep and goats in parts of Europe, Africa, Asia
  • Caused by M. agalactiae
  • Mastitis, arthritis and conjunctivitis following parturition
  • Causes abortion
  • Fatal pneumonia in young animals
  • Shed in milk; localised in supramammary lymph nodes
  • Inactivated, attenuated vaccines available


Contagious caprine pleuropneumonia

  • Caused by M. capricolum subsp. capricolum'; occasionally M. mycoides subsp. capri or M. mycoides subsp. mcoides
  • Occurs in Africa and Turkey
  • Pneumonia, fibrinous pleurisy, pleural exudate, consolidated and emphysematous lungs
  • Aerosol transmission; highly contagious
  • Identified by growth inhibition disc tests
  • Inactivated vaccines available


Enzootic pneumonia of pigs

  • Caused by M. hyopneumonia


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