Difference between revisions of "Mycoplasmas"

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#REDIRECT[[:Category:Mycoplasmas]]
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|linkpage =Bacteria
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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


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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