Overview

  • Cause disease in animals and are important zoonoses
  • 10 species of which Yersinia pestis, Yersinia pseudotuberculosis amd Yersinia enterocolitica are pathogenic to animals and humnans
  • Rodents provide a reservoir of Yersinia pestis, which is the cause of human plague; fleas transmit the infection to other animals and humans
  • Yersinia pseudotuberculosis and enterocolitica reside in the intestine of domestic and wild animals and birds
  • Birds may cause mechanical transfer of the organisms

Characteristics

  • Enterobacteria, but grow more slowly and at lower temperatures than other enterobacteria
  • Gram negative, non-spore forming, facultative anaerobes - rods or colibacilli
  • Non-lactose fermentors
  • Facultative intracellular pathogens
  • Show bipolar staining in Giemsa-stained smears from animal tissue
  • Pathogenic strains identified by serotyping and biotyping

Pathogenesis

  • Invasive Yersinia grow inside macrophages
  • Survive in phagolysosomes and do not interfere with degranulation or lysosomal fusion
  • Resistant to macrophage killing mechanisms
  • The bacteria destroy macrophages in lymph nodes, liver and spleen, causing septicaemia

Clnical infections

Diagnosis

Control

Treatment