Pasteurella species and Mannheimia haemolytica
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
- Involved in subcutaneous abscesses due to cat bites
- 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 cellulitis
- Some strains involved in Atrophic rhinitis of pigs, and produce osteolytic toxin
- Involved in 'Snuffles' in rabbits, a mucopurulent rhinosinitis
- Can cause pneumonia and mastitis in sheep
- Associated with pneumonic pasteurellosis in cattle, as well as enzootic pneumonia in calves
- 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
- Pneumonia 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
- Pasteurella may be found in deep pyoderma
Mannheimia
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
- Peritonitis in sheep
- Permeability types of pulmonary oedema
- Septicaemia in young lambs
- Causes gangrenous 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