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Pasteurella multocida

ISSN 2398-2977

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Synonym(s): P. multocida

Introduction

Classification

Taxonomy

  • Family:Pasteurellaceae.
  • Genus:Pasteurella.
  • Closely related to the generaActinobacillusandHemophilus.

Etymology

  • Pasteurella- after Louis Pasteur (1822-1895).
  • Multocida: L:multus- much, many;cidere- to kill; ie pathogenic for many animals.

Distribution

  • Worldwide.

Significance

  • Commensals on the mucous membranes of respiratory and gastrointestinal tract.
  • Carrier rate for different species varies.
  • Reported in horses very rarely, in isolated cases of abortion   Abortion: overview  , ulcerative lymphangitis , respiratory disease ('transport pneumonia') - often in mixed infections.

Active Forms

Active Form 1

Morphology

  • Oxidase-positive gram-negative coccobacilli.
  • Small non-hemolytic colonies after 24 hours incubation.
  • Type A strains produce relatively large mucoid colonies.

Taxonomy

  • Differentiated from the enteric bacteria:
    • Morphology - characteristic colonies.
    • Biochemistry - oxidase-positive.
    • Microbiology - gram-negative pleomorphic rods.

Color

  • Grayish white on blood agar.

Tolerances

Temperature
  • Optimal growth at 37°C.
  • Killed by heating to 50°C for 30 min.
Humidity
  • Survives best in moist environments.
Ultraviolet
  • Rapidly killed by exposure to ultraviolet light.
Other
  • Very susceptible to disinfectants.

Development

Growth
  • Facultative anaerobes.
  • Does not grow on MacConkey agar.
Reproduction
  • Binary fission; non-sporulating.
Longevity
  • Can survive for months in bird carcasses.

Resting Forms

Clinical Effects

Epidemiology

Habitat

  • Carried on mucous membranes of dogs, cattle and cats.

Lifecycle

  • Multiplies on mucous membranes of host.

Transmission

  • Usually via the respiratory tract.

Pathological effects

  • Antibodies are protective against hemorrhagic septicemia in cattle, but little is known about immunity in other species.
  • All members of the genus are probably parasites.
  • Stress, eg concurrent viral infection   →   becomes pathogenic.
  • Endotoxins are important in septicemic diseases, eg bovine hemorrhagic septicemia.
  • Thermolabile dermonecrotoxin is important in atrophic rhinitis of pigs.
  • Animal to animal spread usually via the respiratory tract; virulence may be enhanced following transmission.
    diseases caused
  • In horses,P. multocidamay cause lower respiratory tract infection ('transport pneumonia'), often in association withStreptococcus equisubspecieszooepidemicus  Streptococcus spp  . Also reported in an aborted fetus.
  • Serogroup A:
    • Pneumonia or suppurative conditions, eg abscesses, mastitis in cattle, sheep, pigs, rabbits and other species.
    • Fowl cholera.
    • Also found as commensals.
  • Serogroup B:
    • Epizootic hemorrhagic septicemia in ruminants.
    • Also found as commensals.
  • Serogroup D:
    • Atrophic rhinitis in pigs (may be in association withBordetella bronchiseptica  Bordetella bronchiseptica  ).
    • Pneumonia in pigs and other animals.
  • Serogroup E:
    • Epizootic hemorrhagic septicemia in cattle and water buffalo in Africa.
  • Serogroup F:
    • Found in turkeys - role unclear.

Other host effects

  • Carried on mucous membranes, especially of carnivores.

Control

Control via chemotherapies

Control via environment

  • Avoid transport stress.

Vaccination

  • Killed vaccine available for cattle, poultry and pigs.
  • Some attenuated, live vaccines used in poultry.

Diagnosis

Useful samples

  • Mastitic milk, pus, tissue, swabs, lung tissue.

Specimen storage

  • Survives in media containing blood or serum at 4°C.

Transport of samples

  • Can be transported in exudates or swabs in transport media.
  • Avoid exposure to ultraviolet light or extremes of temperature.
  • Package accordingly to mailing regulations   Transportation of diagnostic specimens  .

Laboratory diagnosis

  • Microscopy: organisms may not be seen in a Gram-stained smear of affected tissue; Giemsa or Leishman-stained smears more likely to show the organisms.
  • Growth: characteristic smell on blood agar; will not grow on MacConkey.
  • Biochemical tests: oxidase- and indole-positive; further biochemical tests to differentiate it from otherPasteurellaspp. Can also be used to identify subspecies ofP. multocida.
  • Serotyping: based on capsular polysaccharides available at reference laboratories. Serogroups A, B, D, E and F have been identified. Somatic typing also performed. Types 1-16 used for typing poultry isolates.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Raidal S L (1995) Equine pleuropneumonia. Br Vet J 151 (3), 233-262.
  • Mohan K, Sadza M, Madsen M et al (1994) Phenotypic characterization of Zimbabwean isolates of Pasturella multocida. Vet Microbiol 38 (4), 351-357 PubMed.
  • Wood J L N, Burrell M H, Roberts C A et al (1993) Streptococci and Pasteurella spp associated with disease of the equine lower respiratory tract. Equine Vet J 25 (4), 314-318 PubMed.
  • Collins F M (1977) Mechanisms of acquired resistance to Pasteurella multocida infection, a review. Cornell Vet 67 (1), 103-138 PubMed.