ISSN 2398-2942      

Mycoplasmas and ureaplasmas


Richard Walker

Emi Barker




  • Class: Mollicutes.
  • Order: Mycoplasmatales.
  • Family: Mycoplasmataceae.
  • Genus: Mycoplasmas:
    • Mycoplasma (over 60 serotypes).
    • Ureaplasma (single species with serotypes).


  • Gk: myco- fungus; plasma- form; mycoplasma- a fungus form; ureaplasma- a form which requires urea.

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Clinical Effects



  • Occur as free-living saprophytes or parasites of animals.
  • Found on mucous membranes of the gastrointestinal, genital and respiratory tracts.
  • Both pathogenic and non-pathogenic mycoplasmas are found on the mucous membranes of animals as commensals.


  • Reproduce by binary fission, sometimes after formation of filaments.
  • Double-stranded DNA genome.


  • Mucosal mycoplasmas:
    • Aerosol, venereal or vertical.
    • Infections may be exogenous or endogenous.
  • Hemotropic myocplasmas:
    • Direct blood transmisstion, eg aggressive interactions.
    • Arthropod-vector, eg via ingestion of blood meals acquired by hemophagocytic activity of arthropod.
    • Vertical suspected (unclear whether pre- or peripartum).
    • Iatrogenic via blood transfusions.

Pathological effects

  • May be latent and clinical disease Mycoplasmosis precipitated by stress.
  • Adhere to mucous membranes or red blood cell membrane; some have structures for attachment.
  • Most remain extracellular and produce various toxins and enzymes that damage and destroy host cells, eg hemolysins and proteases.
  • In some species (eg humans, pigs) mycoplasmas are capable of intracellular survival, resulting in antimicrobial resistance.
  • Pathogenic mycoplasma infection often occurs in the respiratory tract cause ciliary paralysis and secondary infection by other microorganisms may occur.
  • Hemotropic mycoplasma (hemoplasma) infection, where organisms parasitize the surface of red blood cells, leads to hemolysis and anemia. In some host species, clinical disease may be seen in immunocompetent individuals (eg cats, pigs), in other host species (eg dogs) disease typically only seen following splenectomy.

Diseases caused

  • Mucosal mycoplasmas:
    • Dogs: pneumonia Lung: bacterial pneumoniaMycoplasma cynos; nephritis, cystitis Cystitis, infertility Infertility: male - overviewMycoplasma canis Mycoplasma canis.
    • Cats: conjunctivitis, pneumonia - Mycoplasma felis.
    • Horses: pneumonia, pleuritis, pericarditis - Mycoplasma felis.
    • Primates: atypical pneumonia - Mycoplasma pneumoniae; genital tract infections - Mycoplasma hominis; urethritis - Ureaplasma urealyticum.
    • Birds: sinusitis, air sacculitis, joint infections, embryo mortality -Mycoplasma gallisepticumMycoplasma meleagridis, Mycoplasma synoviae, Mycoplasma iners, Mycoplasma iowae.
    • Cattle: contagious bovine pleuropneumonia - Mycoplasma mycoides subspecies mycoides (small colony type; type species for this genus) and other species; mastitis, athritis, otitis interna - Mycoplasma bovis.
    • Goats: septicemia, arthritis, mastitis - Mycoplasma mycoides subspecie smycoides (large colony type), Mycoplasma capricolum, Mycoplasma putrifaciens.
    • Swine: enzootic pneumonia, arthritis, polyserositis - Mycoplasma hyopneumoniae, Mycoplasma hyorhinis, Mycoplasma hyposynoviae.
  • Hemotropic mycoplasmas:
    • Dogs: mycoplasmosis - Mycoplasma haemocanis Mycoplasma haemocanis and ‘Candidatus Mycoplasma haemomatoparvum’.
    • Cats: feline infectious anemia - Mycoplasma haemofelis, ‘Candidatus Mycoplasma haemominutum’, and ‘Candidatus Mycoplasma turicensis'.
    • Horses.
    • Primates: ‘Candidatus Mycoplasma kahaneii’; ‘Candidatus Mycoplasma aoti’.
    • Cattle: Mycoplasma wenyonii; ‘Candidatus Mycoplasma haemobos’.
    • Sheep and goats: Mycoplasma ovis; ‘Candidatus Mycoplasma haemoovis’.
    • Swine: Mycoplasma suis.

Other Host Effects

  • Many are mucosal myoplasmas are commensals on mucous membranes, especially upper respiratory, lower alimentary and genitourinary tracts.
  • Pathogenesis may involve immune-mediated tissue damage and formation of autoantibodies.
  • Hemotropic mycoplasmas have only been detected parasitizing red blood cells. Theoretical concern that increased myeloid cell turnover due to low grade hemolysis could increase risk of neoplastic transformation, particularly in the presence of oncogenic viral infections or following irradiation.


Control via chemotherapies

  • Mycoplasmal organisms may develop resistance to antimicrobial drugs Therapeutics: antimicrobial drug.
  • Macrolides and fluoroquinolones (enrofloxacin Enrofloxacin) used most commonly for mucosal mycoplasmas.
  • Tetracyclines and fluoroquinolones used most commonly for hemotropic mycoplasmas.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Becher A C, Spergser J, Aurich C et al (2013) Cooled storage of canine semen: in vitro effects of different concentrations of an antibiotic combination on growth of mollicutes. Reprod Domest Anim 48 (6), 961-966 PubMed.
  • Messick J B, Walker P G, Raphael W et al (2002) 'Candidatus mycoplasma haemodidelphidis' sp. nov., 'Candidatus mycoplasma haemolamae' sp. nov. and Mycoplasma haemocanis comb. nov., haemotrophic parasites from a naturally infected opossum (Didelphis virginiana), alpaca (Lama pacos) and dog (Canis familiaris): phylogenetic and secondary structural relatedness of their 16S rRNA genes to other mycoplasmas.​ Int J System Evol Micro 52 (Pt 3), 693-698 PubMed.
  • Walker R D, Walshaw R, Riggs C M et al (1995) Recovery of two mycoplasma species from abscesses in a cat following bite wounds from a dog. J Vet Diagn Invest (1), 154-156 PubMed.
  • Randolph J F, Moise N S, Scarlett J M et al (1993) Prevalence of mycoplasmal and ureaplasmal recovery from tracheobronchial lavages and prevalence of mycoplasmal recovery from pharyngeal swab specimens in dogs with or without pulmonary disease. Am J Vet Res 54 (3), 387-391 PubMed.
  • Weisburg W G, Tully J G, Rose D L et al (1989) A phylogenetic analysis of the mycoplasmas: basis for their classification. J Bacteriol 171 (12), 6455-6467 PubMed.

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