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Yersinia species

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can mimic appendicitis. swollen lymph nodes, fever. can develop severe arthritis (HLA-B27) ... can mimic appendicitis. swollen lymph nodes, fever ... – PowerPoint PPT presentation

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Title: Yersinia species


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
  • Gram-negative, pleomorphic bacillus
  • Facultative anaerobe
  • Optimal growth at 28o C
  • Facultative intracellular parasites

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 by
    PMN

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 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

16
Yersinia enterocolitica
  • Gram-negative rod, motile
  • Isolated from rodents, farm animals, cats and
    dogs
  • Humans acquire infection via fecal-oral route
  • Most common in Scandinavia and Western Europe

17
Symptoms
  • abdominal pain, diarrhea
  • can mimic appendicitis
  • swollen lymph nodes, fever
  • can develop severe arthritis (HLA-B27)

18
Diagnosis
  • Isolation of organisms from feces, blood, or
    lymph node biopsy

19
Treatment
  • Septicemia - gentamicin or chloramphenicol
  • Enteritis - self limiting and usually not treated

20
Yersinia pseudotuberculosis
  • Animal pathogen
  • Infects wild and domestic animals
  • Causes necrotic lesions in the liver, spleen, and
    lymph nodes
  • Infection via oral route from infected animal
    fecal material

21
Symptoms
  • abdominal pain, diarrhea
  • can mimic appendicitis
  • swollen lymph nodes, fever
  • Rarely invades bloodstream or cause internal
    lesions
  • May cause arthritis

22
Treatment
  • ampicillin, streptomycin, or tetracycline
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