L12 Yersinia

Question 1

What disease does Yersinia spp. cause?

Answer 1

Food poisoning, plague

Question 2

How does Yersinia spp. cause disease?

Answer 2

Invasion, vector borne, T3SS

Question 3

Features of Yersinia?

Answer 3

• Vector borne
• Gram neg
• Rod-shaped
• Psychrotrophic

Question 4

Examples of psychrotrophic pathogens?

Answer 4

Listeria monocytogenes, Yersinia spp.

Question 5

Which family is Yersinia part of?

Answer 5

Enterobacteriaceae

Question 6

Which strains of Yersinia cause food poisoning (yersiniosis)?

Answer 6

Yersinia entercolitica

Yersinia pseudotuberculosis

Question 7

Which strain of Yersinia causes plague/Black Death?

Answer 7

Yersinia pestis

Question 8

Yersinia reservoir appears to be?

Answer 8

Animals (swine, rats, ticks [plague])

Question 9

Yersiniosis symptoms?

Answer 9

Diarrhoea, abdominal pain, fever, appendicitis-like

Question 10

Pathogenesis of Yersinia enterocolitica & pseudotuberculosis

Answer 10

• Both invasive
• Both species are transmitted through M cells
• Cause a localised inflammatory response
• Eventually eliminated by PMNs

Question 11

Sequelae of yersiniosis?

Answer 11

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

Question 12

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

Answer 12

1. Adhesin/invasion: YadA - adhesin which can force uptake (by M cells)
2. Iron uptake: high pathogenicity island (HPI)
3. Antiphagocytic proteins: Yops (>11), Ysc (T3SS) export Yops
4. Regulatory proteins: Lcr

Question 13

What is the YadA adhesive protein important in?

Answer 13

Serum resistance - inhibits the classical pathway of complement activation

Question 14

Discuss the T3SS in Yersinia

Answer 14

• 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

Question 15

Toxin produced by Yersinia?

Answer 15

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

Question 16

Treatment for yersiniosis?

Answer 16

Usually self-limiting for gastroenteritis

Question 17

What causes the Bubonic Plague/Black Death?

Answer 17

Yersinia pestis

Question 18

How is the Black Death acquired?

Answer 18

Via insect bites or person to person contact

Question 19

3 types of plague?

Answer 19

• Bubonic plague: most common, infection of the lymph system, swollen LNs
• Pneumonic plague: most serious, infection of lung macrophages that leads to pneumonia
• Septicaemic plague: bacteria reproduce in blood, characterised by LPS shock

Question 20

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

Answer 20

Pneumonic plague

Question 21

Difference between primary and secondary pneumonic plague?

Answer 21

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)

Question 22

How is plague usually treated?

Answer 22

By Streptomycin