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Microbiology > 11. Yersinia > Flashcards

11. Yersinia Flashcards

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Biology 101 flashcards
1
Q

What disease does Yersinia spp. cause?

A

Food poisoning, plague

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2
Q

How does Yersinia spp. cause disease?

A

Invasion, vector borne, T3SS

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3
Q

Features of Yersinia?

A
  • Vector borne
  • Gram neg
  • Rod-shaped
  • Psychrotrophic (like low temperatures)
  • Enterobacteriaceae (Shigella, E.coli, Salmonella)
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4
Q

Examples of psychrotrophic pathogens?

A

Listeria monocytogenes, Yersinia spp.

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5
Q

Which family is Yersinia part of?

A

Enterobacteriaceae

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6
Q

Which strains of Yersinia cause food poisoning (yersiniosis)?

A

Yersinia entercolitica &
Yersinia pseudotuberculosis
- food or waterborne

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7
Q

Which strain of Yersinia causes plague/Black Death?

A

Yersinia pestis

Tick borne , reservoirs in rodents
Animals (swine, rats, ticks [plague])

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8
Q

Yersiniosis symptoms?

A

Diarrhoea, abdominal pain, fever, appendicitis-like

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9
Q

Pathogenesis of Yersinia enterocolitica & pseudotuberculosis

A
  • Both invasive
  • Both species are transmitted through M cells
  • Cause a localised inflammatory response - cause symptoms
  • Eventually eliminated by PMNs (white blood cells)
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10
Q

Sequelae of yersiniosis?

A

Can have a complication of Reiter’s Syndrome (an autoimmune response due to cross-reaction between Abs & host Ags

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11
Q

Many of the Yersinia virulence traits are encoded by a large virulence plasmid (pCD1 or pYV). The plasmid encodes 4 main gene categories:

A
  1. Adhesin/invasion: YadA - adhesin which can force uptake (by M cells)
  2. Iron uptake: high pathogenicity island (HPI)(Yersiniobactin - siderophore)
  3. Antiphagocytic proteins: Yops (>11), delay phagocytosis, Ysc (encodes the T3SS) exports Yops via the T3SS
  4. Regulatory proteins: Lcr - regulates all the genes
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12
Q

What is the YadA adhesive protein important in?

A

Binds to collagen

Serum resistance - inhibits the classical pathway of complement activation

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13
Q

Discuss the T3SS in Yersinia

A
  • T3SS found in all pathogenic strains of Yersinia
  • Classic needle-like structure - made of polymer YscF, with a tip YopB
  • Effector proteins (Yop proteins) excreted into cell
  • Immunosuppression - dampens immune response of some cells to help colonise & start infection
  • Interacts with key signalling pathways
  • Antiphagocytic - by interfering with actin rearrangement necessary for phagocytosis
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14
Q

Toxin produced by Yersinia?

A

Yst: Yersinia stable toxin
similar to E. coli ST (small peptide)
3 variants: ystA, ystB, ystC

*role in virulence of Y.entercolitica not yet established

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15
Q

Treatment for yersiniosis?

A

Usually self-limiting for gastroenteritis

  • wait it out
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16
Q

What causes the Bubonic Plague/Black Death?

A

Yersinia pestis

17
Q

How is the Black Death acquired?

A

Via insect bites or person to person contact

Bacteria enter bloodstream and travel to the lymph nodes where they cause swelling

18
Q

3 types of plague?

A
  • Bubonic plague: most common, infection of the lymph system, swollen LNs
  • Pneumonic plague: most serious, infection of lung macrophages that leads to pneumonia, primary and secondary, high transmissibility & fatality
  • Septicaemic plague: bacteria reproduce in blood, characterised by LPS shock, contracted like bubonic plague but is most often seen as a complication of untreated bubonic or pneumonic plague
19
Q

Large outbreaks of plague would be associated with large numbers of which type of plague?

A

Pneumonic plague

20
Q

Difference between primary and secondary pneumonic plague?

A

Primary - contracted when infected droplets are directly inhaled (can be passed from person to person)
Secondary - develops when bubonic or septicaemic goes untreated (moves to lungs and then can be spread to someone else)

21
Q

How is plague usually treated?

A

By Streptomycin

22
Q

3 strains of Yersinia?

A

Y. enterocolitica
Y. pseudotuberculosis
Y. pestis

23
Q

What is Yersinia commonly mistaken for?

A

Appendicitis

  • abdominal pain
  • fever
24
Q

True of false: Yersinia is part of the normal human flora.

A

False

25
Q

Is YadA an important virulence factor in all strains?

A
  • Important virulence factor in Y. enterocolitica
  • Dispensable in Y. pseudoTB
  • Pseudogene in Y. pestis
26
Q

How is Y.pestis spread

A

Rodent population have it, are fed on by fleas, fleas pick it up, rodents all die
because of it, fleas have no food, feed on humans → plague

27
Q

How many plague pandemics have there been? How many deaths were caused?

A
  1. Justinian Plague
  2. Black Death (most severe)
  3. Chinese province of Yunnnan

200 million deaths

28
Q

How do we know Y. pestis was responsible for Justinian Plague?

A

Plague graves fin Bavaria, radiocarbon dating, DNA extracted from teeth, DNA was enriched with Y. pestis and sequenced, confirmed presence

29
Q

Death toll of Justinian Plague?

A

Killed 50-60% of European population

30
Q

Death toll of black plague?

A

50% of European population - 25 million

50% of China population - 60 million, 70% in Muslim world

31
Q

Plague in Ireland

A
32
Q

What is the most recent outbreak of Plague?

A

Madagascar November 2017

2348 cases, 202 deaths

33
Q

What plasmids is Y. pestis host to?

A 
Plasmid pCD1 (pYV)
and two others, plasmid pPCP1 (pPla/pPst)  and pMT1 (pFra) which are not carried by Yersinia species
34
Q

What did Y. pestis emerge from?

A

Y. pseudotuberculosis (20,000 years ago)

35
Q

True or False: Y. pestis contains many of the same genes as Y. pseudotuberculosis

A

TRUE

  • Pseudogenes- Y. pestis has same genes as YP but they aren’t expressed
  • Over 150 of these, including YadA
  • One way via which these bacteria can rapidly evolve
36
Q

Symptoms of Bubonic plague

A

Fever, headache, chills, weakness, swollen and tender lymph glands

37
Q

Symptoms of Pneumonic plague

A

Fever, headache, weakness, rapid onset of pneumonia (usually accompanied by: shortness of breath, chest pain, cough, bloody or watery sputum)

38
Q

Symptoms of Septicemic plague

A

Fever, chills, weakness, abdominal pain, shock, bleeding underneath skin
or other organs

Microbiology (13 decks)

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