Enteric Bacteria

Question 1

heat-labile enterotoxin “LT”

Answer 1

(cholera-like AB-exotoxin): ADP-ribosylation of G protein ► cAMP
►
loss of water + electrolytes ► watery diarrhea (e.g. foodborne enterotoxigenic ETEC E.coli)
In Shigella dysenteriae this set of symptoms “diarrhea with blood” is combined with
intestinal cell invasion, apoptosis and neutrophilia (► “pus”) to define “dysentery”.
Traveller’s diarrhea

Question 2

Shiga toxin

Answer 2

(AB-exotoxin cytotoxin): inactivation of 60S ribosome subunit by removal of a
specific adenine base from a nucleotide of 28S rRNA ► stop translation ► cell death ►
bloody diarrhea (e.g. foodborne enterohemorrhagic EHEC E.coli O157:H7)
In addition: ► hemolytic uremic syndrome ► kidney damage

Question 3

Shigella dysenteriae

Answer 3

In Shigella dysenteriae this set of symptoms “diarrhea with blood” is combined with
intestinal cell invasion, apoptosis and neutrophilia (► “pus”) to define “dysentery”.

Question 4

E.coli Virulence Factors

Answer 4

heat-labile enterotoxin “LT”
Shiga toxin (AB-exotoxin cytotoxin):

Question 5

Shigella dysenteriae Virulance Factors

Answer 5

Shiga toxin: bloody watery diarrhea

Ø Cell invasion ►neutrophils ► pus dysentery

Question 6

Shigella dysenteriae are taken up by…..

Answer 6

M-cells

Question 7

Shigella dysenteriae enters through

Answer 7

the inferior and lateral aspects of epithelium cells

Question 8

Typhoid Fever

Answer 8

Salmonella

Question 9

Salmonella Virulence

Answer 9

Type III

Question 10

Salmonella invasion of intestinal epithelia

Answer 10

M cell uptake through ruffles: transport through epithelial layer.
• Electrolyte release to lumen (diarrhea/gastroenteritis).
• Release of inflammatory exudate.
• Transport to lymph nodes / transient bacteremia

Question 11

Tranport to lymph nodes

Answer 11

Salmonella

Question 12

Human Reservoir

Answer 12

Salmonella stored in gallbladder Typhoid May

Question 13

Salt Tolerant

Found in Marine Enviroments

Answer 13

Vibro Cholerae

Question 14

Vibro Cholerae

Virulance Factors

Answer 14

toxin co-regulated pilus (tcp): adhesion to small intestinal epithelia
Ø cholera toxin (heat-labile exotoxin “LT”): protein A causes cAMP rise + watery diarrhea
Ø an additional toxin “ST” can raise cGMP levels with a similar effect

Question 15

toxin co-regulated pilus (tcp): adhesion to small intestinal epithelia

Answer 15

Vibrio cholerae

Question 16

TCP production is induceed
(..................), while
production in other
environments appears to
be (....................)

Answer 16

TCP production is
induced within the
intestine, while
production in other
environments appears to
be minimal

Question 17

CTXφ (a bacteriophage)

Answer 17

Virbo cholerae

Question 18

ctxA and ctxB encode the

proteins that comprise

Answer 18

cholera toxin

Question 19

formalinized whole-cell vaccine:

several doses; partial protection for 2-3 yrs

Answer 19

Cholera Toxin

Question 20

Common epidemic strain Vibro Cholerae

Answer 20

serovar O1

Question 21

Vibro Cholerae O1 vaccine (India 1992) does not protect

Answer 21

O139 with capsule

Question 22

Campylobacter Jejune

Answer 22

Growth in intestinal tract:
§ invade intestinal epithelial cells or
grow below epithelial layer.
§ inflammatory respons

Question 23

Disease resolves without treatment in <1 week

Creates protective immunity

Answer 23

Campylobacter Jejune

Question 24

Zoonosis: animal reservoir (intestinal)
Transmission: contaminated food (poultry, milk)
(e.g. in >89% of raw chicken)
Disease: gastroenteritis, diarrhea, dysentery

Answer 24

Campylobacter Jejune

Question 25

Campylobacter Jejune Shape

Answer 25

Curved S shaped.