Category: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


Mycoplasma mycoides subsp. mycoides



Mycoplasma bovis

Mycoplasma agalactiae


Mycoplasma capricolum subsp. capricolum

Mycoplasma mycoides subsp. mycoides

Mycoplasma hyopneumoniae

Mycoplasma hyorhinis

Mycoplasma hyosynoviae

Mycoplasmas of poultry

Mycoplasma gallisepticum

Mycoplasma meleagridis

Mycoplasma synoviae

Other mycoplasmas