Lecture 20 Salmonella and Yersinia .

Question 1

What are the common themes?

Answer 1

• facultative anaerobic rods
• use enteritis and systemic diseases
• type III secretion
• Both require adherence to intestinal epithelial cells, particularly the M-cells of Peyer s Patches to gain access to extra-intestinal sites.
• interact with macrophages

Question 2

What are the subgroups of Salmonella enterica?

Answer 2

Enterica/cholerasuis
salamae
arizonae
diarizonae
houtenae
indica

Question 3

Which salmonella strain are found in humans and mammals?

Answer 3

enterica

Question 4

Salmonella enterica is prominently found in?

Answer 4

reptiles and the environment .

Question 5

Salmonella is mostly found in what type of hosts?

Answer 5

warm blooded animals

Question 6

What are the characteristics of salmonella?

Answer 6

• gram negative bacilli with peritrichous flagella
• non-spore forming, non-lactose fermentation (except s. Arizona
• H2S formation
• SS agar, hektoen, XLT, McConkey
• serology based on H, O, and flagella
• capsule, Vi antigen

Question 7

What are the sx of non-typhoidal salmonella infections?

Answer 7

-fever, abd cramps, diarrhea (possibly bloody), occasionally can establish localized infection (septic arthritis) or progress to sepsis.

Question 8

How is salmonella transmitted?

Answer 8

ingested of contaminated food, water, or animal contact

Question 9

What are the prevalent serotypes of salmonella?

Answer 9

-S typhimurium, S enteritidis, S. Newport.

Question 10

What is the pathogenesis of salmonella?

Answer 10

1. oral ingestion
   2.infectious dose depending on food: lower if gastric acidity is buffered
2. bacteria travel to the distal ileum-uptake is mediated by M-cells and patrolling CD18+ cells
3. invasion of theses cells mediated by SPI1
   5.ruffing of epithelial cell facilitates uptake of salmonella
4. once across intestinal epithelial cell, salmonella encounters phagocytic cells in lamin propia
   Survival in phagocytic cell depends on SPI2 gene.

Question 11

What are key functions for Salmonella Pathogenicity Islands (SPI1)?

Answer 11

• ability to invade host epithelial cells
• virulence of Salmonella by the oral route
• required to survive and replicate in host macrophages

Question 12

What does SipA do?

Answer 12

actin filaments that cause membrane ruffling

Question 13

What does sop D/B do?

Answer 13

promote chloride and fluid secretion

Question 14

How does SPI2 protect salmonella from phagosome?

Answer 14

• products prevent the accumulation of toxic oxidative products by preventing NADPH oxidase complex from forming on phago
• effector proteins are exported into the cytoplasm
• prevent maturation of phago

Question 15

What is typhoid fever characterized by?

Answer 15

• fever, headache, constipation, malaise, chills, and myalgia. Diarrhea uncommon and vomiting is not usually severe.
• confusion, delirium, intestinal perforation, and death in sever cases

Question 16

How is typhoid passed on?

Answer 16

water or food. Large epidemics due to fecal contamination

Question 17

Are there vaccines for Typhoid?

Answer 17

Ty21a live oral

Vi-antigen injectable form

Question 18

What are the characteristics of Salmonella Typhi?

Answer 18

• produce Vi-antigen by SPI7
• Vi antigen is often described as being anti-phagocytic
• Vi antigen involved in shielding typhi from stimulating TLR5 and TLR4
• over 200 pseudogenes

Question 19

How do NTS and S typhi interact differently with the immune system?

Answer 19

S Typhi indifferent to components of innate immunity that play a crucial role in resistance to NTS

Question 20

What is Salmonella-mediated enteritis specifically caused by?

Answer 20

toxin or enterotoxin

Question 21

What is needed to induce neutrophil migration and inflammation of Salmonella-mediated enteritis?

Answer 21

-Products of SPI1, induced tissue damage is cause of fluid formation

Question 22

What are the characteristics of Yersinia?

Answer 22

11 species
Y. enterocolitica and Y.pseudotuberculosis are human pathogens, but found in animals too
Swine major reservoir but does not succumb to infection

Question 23

What is the pathogenicity of Yersinia enterocolitica?

Answer 23

1. ingestion of contaminated food
2. adhere to and invade M-cells, encounter macrophages
3. growth takes place in lymph nodes, spleen and liver
4. Usually does not cause septicemia. Usually immuno compromised people who are iron-overloaded or being treated with deferoxamine

Question 24

What are the important virulence factors of Yersinia?

Answer 24

1. invasin
2. yops (EOTHP)
3. yersiniabactin

Question 25

What is invasin?

Answer 25

protein expressed on the surface of the bacterium that facilitates uptake by host cell

Question 26

What is yops?

Answer 26

group of proteins produced on virulence plasmids and pathogenicity islands that are unique to Yersinia. secreted by type III secretion system

Question 27

What is Yersiniabactin?

Answer 27

siderophore that is able to bind and transport of extracellular iron onto the cell.

Question 28

What doe Yop E do?

Answer 28

Depolymerizes actin

Question 29

What does Yop O do?

Answer 29

phosphorylates host proteins-disrupts cell signalling

Question 30

What does Yop T do?

Answer 30

depolymerizes actin

Question 31

What does YopH do?

Answer 31

dephosphorylation of signal transduction proteins

Question 32

What does Yop P do?

Answer 32

inhibits macrophage apoptosis and prevent TNF alpha release