Escherichia coli

Question 1

gram stain and hemolysis

Answer 1

gram positive rod, beta hemolytic

Question 2

media growth

Answer 2

grows on MacConkey, MacConkey-Sorbitol, XLD (yellow), HE (yellow), EMB agar (metallic green sheen)

Question 3

Appearance on MacConkey

Answer 3

lactose fermenting, flat, dry, pink colonies with surrounding darker pink area of precipitated bile salts

Question 4

appearance on EMB

Answer 4

green

Question 5

special conditions

Answer 5

facilitative anaerobic

Question 6

what test most often identifies it

Answer 6

Indole test

Question 7

IMVPC

Answer 7

+ + - -

Question 8

lactose fermentation

Answer 8

positive

Question 9

H2S production

Answer 9

negative

Question 10

Oxidase

Answer 10

negative

Question 11

Indole production

Answer 11

positive

Question 12

Catalase

Answer 12

positive

Question 13

motility

Answer 13

positive

Question 14

TSI

Answer 14

A/A

Question 15

LIA

Answer 15

K/K

Question 16

what is unique about E. coli

Answer 16

most common clinical isolate

Question 17

what diseases does it cause

Answer 17

UTI’s, Neonatal meningitis, intestinal disease, nosocomial infections

Question 18

what are the 5 strains

Answer 18

EHEC- Enterohemorrhagic E. coli
EAEC- enteroaggregative E. coli
ETEC- enterotoxigenic E. colic
EIEC- enteroinvasive E. coli
EPEC- enteropathogenic E. coli

Question 19

EHEC - enterohemmorrhagic E. coli

Answer 19

produces a deadly bloody diarrhea often associated with Hemolytic Uremic Syndrome, caused by undercooked beef or raw milk; often cause of food recalls; no fermentation of sorbitol on Mac-Sorbitol; produce Shiga toxin

Question 20

EAEC- enteroaggregative E. coli

Answer 20

recovered from children with chronic diarrhea

Question 21

ETEC- enterotoxigenic E. coli

Answer 21

produces heat-stable (ST) and heat-liable (LT) toxins, which are plasmid-coded; Traveler’s diarrhea, of short duration with complete recovery

Question 22

EIEC- enteroinvasive E. coli

Answer 22

produces a dysentery-like disease in poor nations

Question 23

EPEC- enteropathogenic E. coli

Answer 23

produces a profound diarrhea in infants in poor nations

Question 24

how is it transmitted

Answer 24

person-to-person, fecal-oral contamination via undercooked beef or milk

Question 25

what are its reservoirs

Answer 25

human GI tract, may be found in female genital tract, not fee living in nature, presence signifies contamination by human feces

Question 26

Vectors?

Answer 26

human, may be found in other animals

Question 27

Serotyping

Answer 27

identifies antigens of strain

Question 28

Vaccines

Answer 28

none

Question 29

Specimens

Answer 29

stool, urine

Question 30

Virulence factors

Answer 30

O- associated with cell wall; about 150 different kinds; heat stable allow for groupings
K- associated with capsule around cell wall; about 90 different kinds; responsible for inhibition of agglutination by specific antibody
Hp associated with flagella; about 50 different kinds