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