Lec 06: Bacterial Pathogens in GI Disorders

Question 1

Most important enterobacteriaceae antigen.

Answer 1

O antigen. This elicits IgM

Question 2

Antigen that imparts virulence

Answer 2

K antigen

Question 3

Antigen that is found on the flagella

Answer 3

H antigen. This elicits IgG

Question 4

most abundant facultative anaerobe in the colon

Answer 4

E. coli

Question 5

Most common type of E.coli

Answer 5

Enterotoxigenic E. coli (ETEC)

Question 6

Most common type of E.coli

Answer 6

Enterotoxigenic E. coli (ETEC)

Question 7

What is the mode of action of heat labile toxin?

Answer 7

sub-unit B attaches to Gm ganglioside of brush
border cells of small intestines to facilitate sub-unit A entry

Sub-unit A: increases cAMP concentration via
activation of adenylate cyclase -> extreme
and prolonged hypersecretion of water and
chloride, while inhibiting sodium reabsorption -> dehydration -> electrolyte imbalance

Question 8

What is the mode of action of heat stable toxin?

Answer 8

STa activates guanylate cyclase in enteric

epithelium -> stimulates fluid secretion

Question 9

What symptoms do you expect from Enteroinvasive E. coli ?

Answer 9

severe abdominal cramps/pain,

malaise, fever and bloody stools

Question 10

What symptoms do you expect from Enteroinvasive E. coli ?

Answer 10

severe abdominal cramps/pain,

malaise, fever and bloody stools

Question 11

What symptoms do you expect from Enteropathogenic E.coli?

Answer 11

severe, watery diarrhea with

dehydration and shock in CHILDREN

Question 12

Enterohemorrhagic E. coli (EHEC) produces what kind of toxin?

Answer 12

Shiga toxin

Question 13

EHEC is (Sorbitol+,Sorbitol-)

Answer 13

Sorbitol -

Question 14

Represent more than 99.5% of salmonella strains.

Answer 14

subspecies I

Question 15

Source of salmonella infection

Answer 15

contaminated food and drink (ie. Dried or frozen eggs, Meat and meat products)

Question 16

Tests done for detection of Salmonella

Answer 16

Widal test (obsolete), TyphiDot

Question 17

Treatment for Salmonella infection

Answer 17

1. ampicillin
2. trimethoprim-sulfamethoxazole
3. 3rd gen cephalosporin (i.e. cefixime)

Question 18

Treatment for Salmonella infection

Answer 18

1. ampicillin
2. trimethoprim-sulfamethoxazole
3. 3rd gen cephalosporin (i.e. cefixime)

Question 19

T or F. Shigella has human reservoirs

Answer 19

True

Question 20

What are the outcomes of severe Shigella infection?

Answer 20

invasion of submucosa, Pseudomembranous enterocolitis

Question 21

Biochemical Properties of Shigella

Answer 21

1. lactose non-fermenters
2. non-motile
3. fermentation of carbohydrates without gas
   production

Question 22

Treatment of Shigella

Answer 22

Ciprofloxacin

Question 23

What is the temperature of growth for Campylobacter?

Answer 23

42 degC

Question 24

biochemical analysis results for Campylobacter

Answer 24

oxidase (+), catalase (+), (+) hippurate hydrolysis

Question 25

biochemical analysis results for Campylobacter

Answer 25

oxidase (+), catalase (+), (+) hippurate hydrolysis

Question 26

T or F. VIbrio cholerae are Facultative anaerobes

Answer 26

True

Question 27

Laboratory diagnosis of Vibro cholerae

Answer 27

thiosulfate citrate bile salt (TCBS) plate held

for 48 hours

Question 28

What is the laboratory diagnosis of H.pylori?

Answer 28

Chocolate agar or Skirrow agar

Question 29

What is the treatment for H.pylori?

Answer 29

Bismuth salt +2 antibiotics

Question 30

Main cause of food poisoning

Answer 30

Bacilus cereus

Question 31

Why can Bacilus cereus can grow in adverse conditions?

Answer 31

They produce spores

Question 32

Lab diagnosis of Bacilus cereus

Answer 32

produce colonies on BAP and Gram +