E.coli and Salmonella

Question 1

Do E.coli form spore ?

Answer 1

NO

Question 2

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

Answer 2

Virulence properties
Interaction with intestinal mucosa
Toxin production
Distinct clinical syndromes

Question 3

Major life threatening diarrhea in young children in developing countries

Answer 3

EPEC

Question 4

EPEC possess adherence factor plasmid and attaches to

Answer 4

Small and large intestine mucosa and destroys the microvilli

Question 5

What is a microvilli

Answer 5

Finger like projections. They inrease surface area and absorption

Also provide the first barrier

Question 6

The attachment-effacement of EPEC is controlled by

Answer 6

A chromosomal gene -eaeA

Question 7

The eaeA gene produces

Answer 7

Intimin

Question 8

Intimin is responsible for

Answer 8

Lesions and adherence

Question 9

EPEC induces a formation of what on host cell surface

Answer 9

Pedestals

Question 10

Attachment and effacement of EHEC gene is by

Answer 10

Eae-A gene

Question 11

EHEC attaches mainly in …

Answer 11

Large intestine

Question 12

EHEC produces large quantities of what toxin ?

Answer 12

Shiga

Question 13

The shiga toxin is encoded by

Answer 13

Bacteriophage

Question 14

EHEC possess a plasmid that encodes attachment

Answer 14

Fimbriea

Question 15

Is EHEC invasive ?

Answer 15

No

Question 16

Is EIEC invasive

Answer 16

Yes

Question 17

ETEC attaches to

Answer 17

Small intestine

Question 18

How does ETEC attaches to small intestine

Answer 18

By a fimbrial colonization factor antigen ( CFA)

Question 19

ETEC produces 1 or 2toxins :

Answer 19

A heat labile toxin ( 60 C,30 min )

Heat stable toxin ( 100 C ,15 min)

Question 20

Characterized by non bloody diarrhea in children and adults

Answer 20

ETEC

Question 21

Traveler’s diarrhea

Answer 21

ETEC

Question 22

Unusual in the US

Answer 22

EIEC

Question 23

Unusual in the US

Answer 23

EIEC

Question 24

Enters and multiply in epithelial cells of the large intestine

Answer 24

EIEC

Question 25

Enter and multiply in epithelial cells of the large intestine

Answer 25

EIEC

Question 26

Posses enteroinvasive plasmid

Answer 26

shigella | EIEC

Question 27

Voluminous bloody or nonbloody diarrhea

Answer 27

EIEC

Question 28

Does EIEC produce enterotoxin?

Answer 28

NO

Question 29

Characteristic stacked brick type adherence

Answer 29

EAEC. ( Enteroadherent ) | EAggEC ( Enteroaggregative )

Question 30

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

Answer 30

Attachment fimbriae

Question 31

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

Answer 31

Persistent diarrhea > 2 weeks in children and in the immunocompromised

Question 32

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

Answer 32

Inability to ferment sorbitol | Lack of glucuronidase activity

Question 33

Human diseases that are attributed to O157:H7

Answer 33

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

Question 34

Overal mortality rate for E.coli 0157:H7

Answer 34

5%

Question 35

Factors contributing to highly variable rate of complications

Answer 35

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

Question 36

Reservoir of E.coli O157:H7

Answer 36

Ruminants : sheep, cattle, deer

Question 37

Modes of transmission of E coli 0157:H7

Answer 37

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

Question 38

Principle foods implicated as vehicles for E coli 0157:H7

Answer 38

Ground beef Roast beef Unpasteurized milk

Question 39

Virulence factor for E coli 0157:H7

Answer 39

* 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

Question 40

what is E coli 0157:H7 acid tolerance

Answer 40

PH 4-4.5

Question 41

Salmonella

Answer 41

Gram - Rod shaped Bacilli Motile

Question 42

Salmonella

Answer 42

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

Question 43

Reservoir of salmonella

Answer 43

Intestinal tract of poultry, pigs, birds and insects

Question 44

Salmonellosis

Answer 44

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

Question 45

What are food vehicles for salmonella

Answer 45

``` Beef Poultry Milk Eggs Vegetables Ice cream Baked foods ```

Question 46

Salmonella Virulence factor

Answer 46

Virulence plasmid Siderophores LPS Toxins

Question 47

What is LPS

Answer 47

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

Question 48

What are salmonella toxins

Answer 48

Enterotoxin | Cytotoxins

Question 49

Describe Enterotoxin

Answer 49

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 .

Question 50

Describe cytotoxin

Answer 50

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

Question 51

Ecoli is gram

Answer 51

Negative

Question 52

Major Difference between EPEC and EHEC

Answer 52

EHEC has shiega toxin

Question 53

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

Answer 53

EHEC