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Flashcards in E Coli Deck (26):
1

what are some advantages of having E Coli in the gut?

produces vitamin K

protects against other pathogens

2

why are some E Coli such a problem?

they acquire virulence genes from salmonella and shingella

3

what are the two major categories of pathogenic E coli?

shiga toxin producing

diarrheagenic

4

what disease does E coli cause?

GI tract- kills w/ diarrhea

5

enterohemorrhagic E coli source of infection

STEC

undercooked food (meat, zoo)
person to person
zoos

more common in summer

6

STEC infectious dose

very low

7

STEC symptoms

abdominal pain
bloody diarrhea
hemolytic uremic syndrome
acute renal failure (most common cause of kidney failure in kids)

bacteremia does not occur- stays in gut

8

STEC incubation period

3 days

9

virulence determinants in STEC

pillus-mediated attachment

LEE island- contains T3SS, Tir, and Intimin

proteins that recruit host actin and cause altered morphology

Shiga-like toxin

Hemolysin

Capsule/LPS/nutrient acquisitions

10

what does the E coli common pillus do?

provide relatively weak attachment

11

T3SS

formation of a "needle" that causes lesions by piercing both the bacteria and host membrane

12

Tir

gene delivered to epithelial cells to allow for E coli attachment

13

Intimin

Tir binding protein on surface of E coli

14

Shiga-like toxin

disrupts eukaryotic protein synthesis and it cytotoxic. does this by cleaving RNA and impacting cytoskeleton

causes bloody diarrhea

attacks kidney, CNS
causes vascular damage
induces HUS
causes renal failure

15

hemolysin

pore forming protein that inserts into how cells membrane

associated with meningitis

found on its own plasmid

16

enteropathogenic E Coli

diarrheagenic EPEC - leading cause of childhood diarrhea in developing countries

caused by person to person contact

localized adherence by bundle forming pilli- multiple e coli attach to same cell

no toxins

17

enterotoxigenic e coli

ETEC- diarrheagenic

"Travelers diarrhea"

fimbrae adhere to enterocytes in small intesting


Toxins:

heat-labile toxin- upregulate adenylate cyclase. causes Cl secretion and impaired Na uptake, causing watery stool

heat stable toxin- alters cGMP w/ similar outcomes to heat-labile toxins

18

enteroaggregative E coli

EAEC- diarrheagenic

childhood diarrhea in developing world- causes persistent diarrhea

more aggressive than EPEC b/c more aggressive adherence

Toxins: EAST (heat stable-like), PET, hemolysin

19

enteroinvasive E coli

EIEC

less common in industrialized nations

attachs w/ non-fimbrial adhesins in colon

invades mucosal cells but does not become systemic

causes bloody diarrhea and mucus in stool

invasion genes similar to shingella

no ST or LT toxins

20

diagnostic tools for e coli

e coli is Lac+ = can be detecteed via EMB or MacConkey agar (shingella and salmonella are Lac-)

O157:H7
- cannot grow on sorbitol (can grow on MacConkey)
- serology agglutination tests

Immunoassay for shiga-like toxin

PCR/DNA probe for virulence genes

Tissue culture

Strain typing

21

diffusely adhering e coli

common in children in developing countries

22

CDC recommends looking for Shiga-toxins in diagnostics

ok

23

EHEC treatment

supportive care only

24

ETEC treatment

loperamide, azithromycin

25

EPEC treatment

antibiotics using susceptibilty testing for severe cases

26

EAEC treatment

fluoroquinolones