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Flashcards in E.coli and Salmonella Deck (53):
1

Do E.coli form spore ?

NO

2

Pathogenic strains of E.coli are grouped into categories based on

Virulence properties
Interaction with intestinal mucosa
Toxin production
Distinct clinical syndromes

3

Major life threatening diarrhea in young children in developing countries

EPEC

4

EPEC possess adherence factor plasmid and attaches to

Small and large intestine mucosa and destroys the microvilli

5

What is a microvilli

Finger like projections. They inrease surface area and absorption

Also provide the first barrier

6

The attachment-effacement of EPEC is controlled by

A chromosomal gene -eaeA

7

The eaeA gene produces

Intimin

8

Intimin is responsible for

Lesions and adherence

9

EPEC induces a formation of what on host cell surface

Pedestals

10

Attachment and effacement of EHEC gene is by

Eae-A gene

11

EHEC attaches mainly in ...

Large intestine

12

EHEC produces large quantities of what toxin ?

Shiga

13

The shiga toxin is encoded by

Bacteriophage

14

EHEC possess a plasmid that encodes attachment

Fimbriea

15

Is EHEC invasive ?

No

16

Is EIEC invasive

Yes

17

ETEC attaches to

Small intestine

18

How does ETEC attaches to small intestine

By a fimbrial colonization factor antigen ( CFA)

19

ETEC produces 1 or 2toxins :

A heat labile toxin ( 60 C,30 min )
Heat stable toxin ( 100 C ,15 min)

20

Characterized by non bloody diarrhea in children and adults

ETEC

21

Traveler's diarrhea

ETEC

22

Unusual in the US

EIEC

23

Unusual in the US

EIEC

24

Enters and multiply in epithelial cells of the large intestine

EIEC

25

Enter and multiply in epithelial cells of the large intestine

EIEC

26

Posses enteroinvasive plasmid

shigella
EIEC

27

Voluminous bloody or nonbloody diarrhea

EIEC

28

Does EIEC produce enterotoxin?

NO

29

Characteristic stacked brick type adherence

EAEC. ( Enteroadherent )
EAggEC ( Enteroaggregative )

30

In EAEC. ( Enteroadherent )
EAggEC ( Enteroaggregative )
A plasmid encodes for the production of

Attachment fimbriae

31

EAEC. ( Enteroadherent )
EAggEC ( Enteroaggregative ) causes what kind of diarrhea

Persistent diarrhea > 2 weeks in children and in the immunocompromised

32

What are 2 main cultural characteristic used to differentiate O157:H7 from other strains

Inability to ferment sorbitol
Lack of glucuronidase activity

33

Human diseases that are attributed to O157:H7

Non bloody diarrhea
Hemorrhagic colitis ( HC)
Hemolytic uremic syndrome ( HUS)
Thrombotic thrombosis/topenic purpura (TTP)

34

Overal mortality rate for E.coli 0157:H7

5%

35

Factors contributing to highly variable rate of complications

Host factor( age difference in immunological response to infecting strain or toxin )
Inoculum size
Treatment
Genotype

36

Reservoir of E.coli O157:H7

Ruminants : sheep, cattle, deer

37

Modes of transmission of E coli 0157:H7

1. Ingestion of contaminated food
2. Person to person spread
3. Contaminated water ( rare)
4. Animal to person

38

Principle foods implicated as vehicles for E coli 0157:H7

Ground beef
Roast beef
Unpasteurized milk

39

Virulence factor for E coli 0157:H7

*0157 mainly attached to large intestine
*Shiga toxin (bacteriophage encoded)
-Stx1 and stx2 (inhibits protein synthesis )
-Associated with HUS
*Intimin ( chromosome-encoded eaeA)
-mediates intestinal colonization
*plasmid p0157
-Enterohemolysin
-catalase

40

what is E coli 0157:H7 acid tolerance

PH 4-4.5

41

Salmonella

Gram -
Rod shaped Bacilli
Motile

42

Salmonella

Gram negative
Rod shaped Bacilli
Motile
S. Typhi and S. Enteritidis

43

Reservoir of salmonella

Intestinal tract of poultry, pigs, birds and insects

44

Salmonellosis

Dz caused by salmonella
Nausea, vomiting, abdominal cramp, diarrhea, fever, headache
Symptoms occur in 12-48 hrs and last 2-6 days

45

What are food vehicles for salmonella

Beef
Poultry
Milk
Eggs
Vegetables
Ice cream
Baked foods

46

Salmonella Virulence factor

Virulence plasmid
Siderophores
LPS
Toxins

47

What is LPS

A major component in the cell membrane of gram - bacteria
It prevents the attack from host immune system

48

What are salmonella toxins

Enterotoxin
Cytotoxins

49

Describe Enterotoxin

A non inflammatory syndrome, triggers a secretory response in the small intestine, watery diarrhea, no white cells in stools

Can be releases into cytoplasm of the host by the bacteria, trigger increase of cAMP and that causes loss of water and electrolyte which causes diarrhea .

50

Describe cytotoxin

An inflammatory response in the colon, diarrhea and white cells in stools

51

Ecoli is gram

Negative

52

Major Difference between EPEC and EHEC

EHEC has shiega toxin

53

O157:H7 is a serotypes of what kind of E.coli

EHEC