Brucella

• Brucella is agent of biological warfare.
• Bruce identified the causative agent of Malta fever in 1887.
• Form both caseating and non caseating granuloma.

Morphology

• Gram-negative
• nonmotile
• noncapsulated
• non-sporing strict aerobic
• intracellular coccobacilli.

Major virulence factor

• LPS which possess endotoxin activity

Resist

• Resistant to freezing and drying.

Resist intracellular killing :

• by suppression of myeloperoxide-hydrogen peroxide-halide system
• production of superoxide dismutase.

Sensitive to

• sunlight
• Heationizing radiation.
  • Pasteurization destroys brucella
  • Transmitted by unpasteurized milk.

Culture

• B. Abortus require 10% CO₂for growth(capnophilic)
• Other three species can grow in air. 
• Erythritol has a specially stimulating effect 
• The  biphasic culture medium used for Brucella culture is Castaneda medium.
• Usually inoculated on trypticase-soy agar/blood culture media
• Optimum temperature is 37^oC.

Classification

• Brucella abortus (cattle)
• B suis(hogs)
• Br Cants (dogs)
• B melitensis (Sheep, goat and camel )