Pasteurella species and Mannheimia haemolytica

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• Peritonitis in sheep
• Permeability types of pulmonary oedema.

• P. multocida in cellulitis in cats

Overview Pasteurella and Mannheimia

• Common commensals of the upper respiratory tract and gastrointestinal tract mucosa of animals
• Usually opportunistic organisms, causing disease during times of stress, low resistance or concurrent infection
• Not part of the human bacterial flora
• Small Gram-negative bacilli or coccobacilli
• Facultative anaerobes
• Oxidase-positive
• May show bipolar staining with polychrome stains such as Wright's stain
• Capsules contain acidic polysaccharides

Pasteurella Properties

• Catarrhal odour
• Produce endotoxins which cause host damage and death
• Their capsules resist phagocytosis

Pasteurella multocida

• Large grey colonies on blood agar
• Not haemolytic
• Do not grow on MacConkey
• Five capsular serotypes, A,B,D,E and F
• Primary and secondary pathogen
• Responsible for secondary infections following primary viral and mycoplasmal infections, especially in the lungs, for example during Enzootic pneumonia of calves and pigs
• Can cause vascular fragility, leading to haemorrhagic disease.

• Typa A
  • Commensal in upper respiratory tract of animals in UK
  • Primary pathogen in avian cholera - a septicaemia in chickens and turkeys
  • Secondary pathogen commomly repsonsible for dog and cat bite wound infections in humans and animals
  • Feline pyothorax and other serositides
  • Some strains involved in Atrophic rhinitis of pigs, and produce osteolytic toxin
  • Involved in 'Snuffles' in rabbits, a mucopurulent rhinosinitis

• Type B
  • Causes Haemorrhagic Septicaemia of cattle in Southern Europe and Asia

• Type D
  • Primary and secondary pathogen
  • Causes atrophic rhinitis along with Bordetella bronchiseptica in pigs
  • Pasteurella multocida adhere to epithelium damaged by Bordetella bronchiseptica
  • Produces an osteolytic toxin (Pmt), which stimulates osteoclasts, inducing bone resorption of the nasal turbinates

• Type E
  • Causes African Bovine Haemorrhagic Septicaemia

Pasteurella pneumotropica

• Carried in nasopharynx of many small rodents
• Causes pneumonia in rodents as a secondary disease

Pasteurella trehalosi

• T biotypes - trehalose fermenters
• Pneumonia in ruminants
• Septicaemic pasteurellosis in feeder lambs
• Mastitis in sheep

Pasteurella canis

• Pneumonia in dogs
• Occasionally infects wounds

Pasteurella caballi

• Equine respiratory tract disease, usually in association with Streptococcus equi subspecies S. zooepidemicus
• Equine peritonitis

Pasteurella aerogenes

• Associated with gastroenteritis and abortion in swine

Mannheimia haemolytica

• Cause of epizootic pneumonia in cattle known as Shipping Fever, Transit Fever or pneumonic pasteurellosis (90% caused by Mannheimia haemolytica Biotype A, serotype 1 but also Pasteurella multocida
• Usually secondary to viral infections such as parainfluenza - 3 or IBR, bacterial infections such as Mycoplasma or environmental stress
• May contribute to Enzootic pneumonia of calves
• Enzootic pneumonia in sheep
• Septicaemia in young lambs
• Causes mastitis in sheep
• Beta-haemolytic on blood agar
• Grow weakly on MacConkey agar
• Odourless
• All are Mannheimia A biotypes (previously Pasterurella haemolytica)
• Strains often produce a cytotoxin, known as leukotoxin, which kills leukocytes of ruminants
• Leukotoxin is a member of the RTX group toxins, and is probably largely responsible for the pathogenicity of the bacteria in septicaemia and pneumonia

Mannheimia glucosida

• Previously biotype A11
• Respiratory condition of ruminants