ISSN 2398-2993      

Mannheimia haemolytica


Veronica Fowler

Tammy Hassel

Synonym(s): Pasteurella hemolytica biotype A




  • Kingdom: bacteria.
  • Phylum: proteobacteria.
  • Class: gammaproteobacteria.
  • Order: pasteurellales.
  • Family: pasteurellaceae.
  • Genus: Mannheimia.
  • Species: Mannheimia haemolytica.
  • Previously known as Pasteurella haemolytica, biotype A.


  • Gk: haima ; L: haema- blood. Gk: lutikê: able to loosen/dissolve.

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Clinical Effects



  • Worldwide distribution.
  • Commensals in the upper respiratory tract of cattle (especially tonsil crypts) and other animals.


  • Commensal until risk factors stimulate replication of M. haemolytica in the upper respiratory tract, from where it is then transferred to the lungs.


  • Infections are endogenous.
  • Transmission occurs primarily when predisposing factors enable the resident flora to overcome the cattle's immune system.
  • Possibly contagious.

Pathological effects

  • M. haemolytica causes pathological effects via:
    • Adhesines (two membrane proteins OmpA and Lpp1).
    • Capsular polysaccharide.
    • Endotoxin (toxic for bovine endothelial cells).
    • Leukotoxin (pore-forming cytolysin).
    • Fimbriae.
    • Iron-regulated outer membrane proteins.
  • All of which have potent effects on neutrophils of ruminants that result in cell death.


Control via animal

Control via chemotherapies

  • Treat early with antibiotics (eg ampicillin Ampicillin or oxytetracycline Oxytetracycline.
  • Vaccination (where appropriate).


  • Vaccines are available but show variable benefits. In some cases, the use of bacterins have been suggested to enhance disease pathogenesis.


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Further Reading


Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Capik S F, White B J, Lubbers B V, Apley M D, Mosier D A, Larson R L & Murray R W (2015) Characterization of Mannheimia haemolytica in beef calves via nasopharyngeal culture and pulsed-field gel electrophoresis. J Vet Diagn Invest 27 (5), 568-75 PubMed.
  • DeDonder K D & Apley M D (2015) A literature review of antimicrobial resistance in
    Pathogens associated with bovine respiratory disease.
    Anim Health Res Rev 16 (2), 125-34 PubMed.
  • Noyes N R, Benedict K M, Gow S P, Booker C W, Hannon S J, McAllister T A & Morley P S (2015) Mannheimia haemolytica in feedlot cattle: prevalence of recovery and associations with antimicrobial use, resistance, and health outcomes. J Vet Intern Med 29 (2), 705-13 PubMed.
  • Klima C L, Alexander T W, Hendrick S & McAllister T A (2014) Characterization of Mannheimia haemolytica isolated from feedlot cattle that were healthy or treated for bovine respiratory disease. Can J Vet Res 78 (1), 38-45 VetMedResource.
  • Timsit E, Christensen H, Bareille N, Seegers H, Bisgaard M & Assié S (2013) Transmission dynamics of Mannheimia haemolytica in newly-received beef bulls at fattening operations. Vet Microbiol 161 (3-4), 295-304 PubMed.
  • VanRensburg E & Du Preez J C (2006) Effect of pH, temperature and nutrient limitations on growth and leukotoxin production by Mannheimia haemolytica in batch and continuous culture. J Appli Microbiol 102 (5), 1273 - 1282.

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