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Yersinia species

Yersinia species. Yersinia pestis Yersinia enterocolytica Yersinia pseudotuberculosis. Plague mortality. Plague has claimed millions of lives: 6th century - killed 100 million 14th century - killed 25 million (1/4 of Europe) 1890s - killed 10 million (Asia). Yersinia pestis : history.

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Yersinia species

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  1. Yersinia species • Yersinia pestis • Yersinia enterocolytica • Yersinia pseudotuberculosis

  2. Plague mortality • Plague has claimed millions of lives: • 6th century - killed 100 million • 14th century - killed 25 million (1/4 of Europe) • 1890s - killed 10 million (Asia)

  3. Yersinia pestis: history • Dr. Yersina identified the causative agent of plague in 1894 • Only sylvatic cases (~400) of plague have been reported in the south-western US

  4. Morphology/Physiology • Facultative intracellular parasites Gram-negative, pleomorphic bacillus Facultative anaerobe Optimal growth at 28o C

  5. Cell Cycle • Mass of plaque bacteria forms in gut of infected flea • Flea regurgitates uncapsulated organisms into bite on animal or human • Most organisms destroyed by PMN, but some entering histiocytes survive • Bacteria re-encapsulate and grow. • Progeny is resistant to intracellular killing byPMN

  6. Symptoms • Draining lymph nodes to become hot, swollen, hemorrhagic and painful (buboes) • continued release of organisms causes septicemia and invasion of lungs (pneumonia) • Circulating organisms cause subcutaneous hemorrhage (Black Death) • Exhaled organisms infect others and cause (pneumonic plague)

  7. The different forms of plague • Sylvatic • In animals (rodents, rabbits, carnivores) only • Bubonic • Flea (bite) to humans • Pneumonic • Human (aerosol) to human

  8. Bubonic Pneumonic Bubonic vs pneumonic plague entry flea-bite inhalation disease buboes, hemorrhage, pneumonia rapid pneumonia flea & exhalation exhaled droplets exit

  9. Virulence Determinants • Calcium dependence at 37o C (lcr) • Proteins V & W • Yops • Envelope (F-1) antigen • Coagulase and Fibrinogen Activator (fibrinolysin)

  10. V and W antigens • Plasmid encoded proteins • Part of the low calcium (lcr) regulated response • Rapid proliferation leading to overwhelming septicemia

  11. Yersinia Outer Proteins (Yops) • Plasmid encoded lcr controlled proteins (11) • Cytotoxic • Inhibit phagocyte migration, engulfment and intracellular killing • Inhibit platelet aggregation

  12. F-1 Antigen • Protein-polysaccharide complex • Highly expressed in the mammalian host • Not expressed in flea host • Antiphagocytic • Antibodies to F-1 are protective

  13. Coagulase and Fibrinolysin • Plasmid encoded proteins • Coagulase causes clotting and microthrombi formation • Fibrinolysin promotes dissemination

  14. Diagnosis • Examination of Buboes aspirate stained smears for bipolar staining • Fluorescent-antibody • Culture/identify organisms (hazardous)

  15. Treatment and Prevention • Streptomycin or tetracycline • Hospitalization and strict isolation • Minimize domestic rat population • Control flea population

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