Gut Infections

Question 1

2 types of gut infections

Answer 1

•local
•systemic

Question 2

What do local infections mean

Answer 2

•stay in the gut
•stick to epithelial cells + modify function

Question 3

What do systemic infections do

Answer 3

•spread from gut
•invade between epithelial
•reach blood and other tissues

Question 4

Are local or systemic infections worse

Answer 4

•systemic

Question 5

Describe enterobacteriaceae

Answer 5

•gram - rods
•share enterobacterial common antigen

Question 6

Nutritional requirements of enterobacteriacaea

Answer 6

•facultative anaerobes
•non selective + selective media

Question 7

Common enterobacteriacaea virulence factors

Answer 7

•endotoxin
•capsule
•antigenic phase variation
•type 3 secretion system
•sequestration of growth factors
•resistance to serum killing
•antibacterial resistance

Question 8

enterobacteriacaea examples

Answer 8

•salmonella
•shigella
•yersinia
•E.Coli
•klebsiella
•enterobacter

Question 9

enterobacteriacaea behaviour

Answer 9

•reduce nitrate
•ferment glucose

Question 10

enterobacteriacaea catalase ability

Answer 10

•catalase positive

Question 11

enterobacteriacaea oxidase ability

Answer 11

•oxidase negative

Question 12

What does MacConkey agar do

Answer 12

•selectively isolate gram - enteric bacteria
•prevents gram + growth

Question 13

What is the functions of type 3 secretion systems

Answer 13

•injects any secretion directly into eukaryotic cells

Question 14

What is the same between type 3 secretions across enterobacteriacaea

Answer 14

•structure of it

Question 15

What is different between type 3 secretion systems in enterobacteriacaea

Answer 15

•effector power
•e.g secretion injected

Question 16

How does MacConkey prevent gram + but encourage gram - growth

Answer 16

•contains crystal violet + bile salts
•(gram - love and gram + hate)

Question 17

How can MacConkey be used to differentiate between enterobacteriacaea species

Answer 17

•based on lactose fermentation ability
•(H+ production)

Question 18

What does colourless mean in MacConkey

Answer 18

•pH hasnt changed
•non lactose fermenting

Question 19

What does pink/red mean on MacConkey agar

Answer 19

•pH has decreased
•lactose fermenting

Question 20

What enterobacteriacaea are lactose fermenting

Answer 20

•e coli
•klebsiella
•enterobacter

Question 21

What enterobacteriacaea are non lactose fermenting

Answer 21

•salmonella
•shigella
•yersinia

Question 22

How will salmonella, shigella and yersinia react on MacConkey agar

Answer 22

•remain colourless

Question 23

How will E. coli, klebsiella and enterobacter react on MacConkey agar

Answer 23

•turn pink/red

Question 24

enterobacteriacaea common cell wall structures

Answer 24

•single flagellum
•fimbriae
•capsule
•LPS (endotoxin)

Question 25

2 disease producing phenotypes of E Coli

Answer 25

1- Diarrhoeagenic E Coli (DEC) 2- Extraintestinal pathogenic E Coli (ExPEC)

Question 26

What does diarrhoeagenic E. coli cause

Answer 26

•gastroenteritis (varying severity)

Question 27

What does extraintestinal pathogenic E Coli cause

Answer 27

•UTIs •meningitis •sepsis

Question 28

Which type of E Coli is usually more dangerous

Answer 28

•Extraintestinal pathogenic E Coli •sepsis

Question 29

What is enterotoxigenic E Coli

Answer 29

•most common diarrhoeagenic E. coli

Question 30

ETEC (enterotoxigenic E Coli) virulence factors

Answer 30

•colonisation factors (CFAs) •enterotoxins - heat stable + heat labile

Question 31

2 types of enterotoxins

Answer 31

*heat stable *heat labile

Question 32

Mechanism of heat stable enterotoxins

Answer 32

•bind to guanylate cyclade C receptor on gut •inc cGMP •hyper secretion + inhibits absorp

Question 33

Mechanism of heat labile enterotoxins

Answer 33

•binds GM 1 receptors on gut •increases cAMP •increase secretion of chloride •decrease abso chloride

Question 34

What is the outcome of both enterotoxins in the gut

Answer 34

Watery diarrhoea

Question 35

ExPEC (Extraintestinal E. coli) virulence factors

Answer 35

•adhesion •biofilm •invasion •inhibit complement •serum survival •auto-transporters

Question 36

Describe campylobacter

Answer 36

•bipolar flagella •benign (outside of human) •pathogenic (human + chicken)

Question 37

Campylobacter prevalence

Answer 37

•leading food borne disease worldwide •from poultry

Question 38

Campylobacter as a pathogen

Answer 38

•inflammation increases gut permeability •spreads to edible tissue of poultry

Question 39

What is cdtA

Answer 39

Toxin released by campylobacter

Question 40

What is the effect of cdtA (cytolethal distending toxin A)

Answer 40

•causes epithelial of gut to apoptose •causes inflammatory •lots of water lost (less absorbed as cells die) •bacteria travel in fluid released and spread through gut

Question 41

Salmonella infectious dose

Answer 41

•very low •~100 can cause big issues

Question 42

Salmonella virulence factors

Answer 42

•ingestion •attach to epithelial and M-cells •live in endocytic vacuoles in cells •can invade to blood and lymphatic •pathogenicity island 1 and 2

Question 43

What does pathogenicity islands code for (1 and 2)

Answer 43

•salmonella secreted invasion protein •type 3 secretion system •intercellular replication •immune system evasion

Question 44

What does pathogenicity islands 1 specifically code for

Answer 44

•salmonella secreted invasion protein

Question 45

What does pathogenicity island 2 specially code for

Answer 45

•intracellular replication •immune system evasion

Question 46

What is the function of endocytic vacuoles for salmonella

Answer 46

Way of replicating and maturing within a safe area without be detected by the immune system

Question 47

Mechanism of antigen uptake via M cells

Answer 47

•across epithelial barrier •m cells uptake antigen by endocytosis (cytosolic side) •transcytosis •antigen loaded cells released •cells migrate to payers patches for T cells

Question 48

Basal membrane of M cells shape and function

Answer 48

•folded open pocket •allows access for dendritic cells