Difference between revisions of "Category:Mycoplasmas"

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|pagetitle =Mycoplasmas
===Overview===
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|pagebody =The Mycoplasmas are small free-living prokaryotic organisms. They cause many diseases, notably respiratory diseases in farm animals including [[Contagious Bovine Pleuropneumonia]]. 
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*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===
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[[Category:Bacterial Organisms]]
 
 
*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 - WikiBlood|neutrophils]] and macrophages and prevent phagocytosis
 
*Mycoplasmas induce proliferation of macrophages and [[[[Monocytes - WikiBlood|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'' small colony type
 
*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
 
*Large colony type causes pleuropneumonia, mastitis, septicaemia and polyarthritis
 
 
 
*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. ''mycoides''
 
*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
 
*''M. mycoides'' subsp. 'mycoides'' causes septicaemia, pleuropneumonia, arthritis and mastitis in goats
 
 
 
 
 
===[[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of pigs|Enzootic pneumonia of pigs]]===
 
 
 
*[[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of pigs|Enzootic pneumonia of pigs]] caused by ''M. hyopneumoniae''
 
*Occur in unfavourable conditions with poor ventilation, overcrowding and temperature fluctuations
 
*Stunted growth rates, coughing and occasionally respiratory distress
 
*Consolidation in apical and cardiac lung lobes
 
*Immunofluorescence of lung tissue and complement fixation test or ELISA used for identification
 
*Treatment includes in-feed antibiotics such as tylosin, lincomycin and tiamulin
 
*Absent in specific-pathogen-free herds
 
 
 
 
 
===''M. hyorhinis'' and ''M. hyosynoviae'' of pigs===
 
 
 
*''M. hyosynovia'' and ''M. hyorhinis'' produce syndromes similar to [[Haemophilus parasuis|Glasser's disease]] with milder expression, rarely menigitis and [[Joints Inflammatory - Pathology#In Pigs|arthritis]]
 
*''M. hyorhinis causes a chronic progressive polyserositis in pigs under 10 weeks old
 
*A fever, laboured breathing, lameness and swollen joints occur
 
*Serofibrinous pleurisy, pericarditis and [[Peritoneal Cavity Inflammatory - Pathology#In pigs|peritonitis]] occur
 
*Treatment includes tylosin and lincomycin
 
*''M. hyorhinis'' causes a polyarthritis in pigs of 10-30 weeks old, leading to transient lameness
 
 
 
 
 
===Mycoplasmas of poultry===
 
 
 
*''M. gallisepticum''
 
**Causes chronic repsiratory disease in chickens and infectious sinusitis in turkeys
 
**Transmission via the egg and aerosol
 
**Reduced egg production
 
**Identification by serum plate agglutination test, haemagglutination inhibition and ELISA
 
**Controlled in specific-pathogen-free flocks
 
**Modified live vaccines and bacterins available
 
*''M. meleagridis''
 
**Hatching problems; airsacculitis in young poults; joint and bone deformities in growers; poor growth rates
 
**Transmitted mainly via eggs and semen
 
**Serum plate agglutination test for identification
 
**In-water tylosin for first 10 days of life
 
**Eggs can be dipped in tylosin
 
*''M synoviae''
 
**Causes infectious synovitis in chickens and turkeys
 
**Transmitted by aerosol
 
**Synovitis, arthritis, respiratory disease
 
**Confirmation by isolation or serology
 
**In-feed tetracycline
 
**Eradication through specific-pathogen-free flocks
 
 
 
 
 
===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 [[Peritoneal Cavity Inflammatory - Pathology#In sheep|peritonitis in sheep]], [[Peritoneal Cavity Inflammatory - Pathology#In goats|peritonitis in goats]] and [[Peritoneal Cavity Inflammatory - Pathology#In pigs|peritonitis in pigs]]
 
[[Category:Infectious_Agents]]
 

Latest revision as of 21:31, 5 November 2010