12.1, 12.2 Microbiology: Gastrointestinal infections

Question 1

What is complete dysentery and what is an example of a causative organism?

Answer 1

Blood/pus/mucus

Shigella

Question 2

What is another term for Shigella? Does it produce a toxin?

Answer 2

EIEC

does NOT produce toxin

Question 3

What organism causing infection is carried in chickens?

Answer 3

Campylobacter

Question 4

What causes pseudomembranous colitis?

Answer 4

Clostridium difficile (antibiotic diarrhea)

Question 5

What causes haemorrhagic colitis?

Answer 5

EHEC (Shigatoxin)

Question 6

What has EAEC picked up?

Answer 6

A shigatoxin encoded phage

Question 7

What is intimin?

What do we find it on?

Answer 7

An adhesion molecule (virulence factor of E.Coli)

EPEC, EHEC

Question 8

What are the degrees of invasion of mucosa? (5)

Answer 8

1. Adhesive enterotoxigenic
2. Adhesive with brush border damage
3. Invasion restricted to mucosa
4. Invasion of submucosa
5. Systemic invasion

Question 9

What organisms are adhesive enterotoxigenic?

Answer 9

Cholera, ETEC

Question 10

What organism is adhesive with brush border damage?

Answer 10

EPEC

Question 11

What organism’s degree of invasion is restricted to mucsosa?

Answer 11

Shigella

Question 12

What organisms invade the submucosa?

Answer 12

Salmonella, Campylobacter

Question 13

What organisms systemically invade?

Answer 13

Salmonella typhi, paratyphi

Question 14

What are the two stages of EPEC adherence?

Answer 14

Stage 1 (plasma mediated): initial adherence, intact microvilli

Stage 2 (chromosomal): late adherence, attachment effacement

Question 15

What is special about EPEC?

Answer 15

BYO Tir R’ with Intimin

LEE pathogenicity island

Question 16

What does Rotavirus do to intestinal architecture?

What is the structure of Rotavirus?

Answer 16

Flattens it

Double caspid layer

Question 17

What are 2 cytotonic exotoxins?

What is a cytotoxic exotoxin?

Answer 17

Cholera toxin, ETEC (LT, ST)

Shiga toxin

Question 18

What do we need enrichment for when culturing faeces?

Answer 18

Salmonella

Question 19

What is a capture assay comprised of?

Answer 19

Solid phase
Capture antibody
Antigen (unknown)-put stool here, wash
Specific antibody (if known)
Label

Question 20

When do we use antimicrobials for diarrhoea? (6)

Answer 20

Cholera
Systemic infections
Immunocompromised patients
Severe Shigella
Protozoal infections
Severe pseudomembranous colitis

Question 21

What do antimicrobials make worse (diarrhoea)?

Answer 21

EHEC, Shiga toxin (phage encoded), stress response genes turn on