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PCM Exam 4 > GI Infections 7 > Flashcards

GI Infections 7 Flashcards

1
Q

what is the cytotoxic effect of Shiga toxin

A
  • A1B5 structure and the A domain is internalized by receptor mediated endocytosis
  • causes irreversible inhibition of the 60S ribosomal subunit → cell death, microvascular damage of intestine and hemorrhage
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2
Q

NAD glyochydrolase is a virulence factor for ______

A

shigella; shuts down ATP production

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3
Q

which inflammatory diarrhea causing organisms can also cause reactive arthritis?

A
  • salmonella
  • shigella
  • yersinia
  • campylobacter

“cant see, cant pee, cant climb a tree”

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4
Q

4 F’s of shigella

A

Food, flies, fingers, feces

ways of transmission for fecal oral. route

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5
Q

inflammatory diarrhea most commonly affects the _____ intestine

A

large

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6
Q

what are some characteristics of enterobacteriaceae

A
  • facultative anaerobes
  • gram NEGATIVE, non spore forming rod shaped abcteria
  • motile EXCEPT for Klebsiella and shigella
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7
Q

is shigella invasive?

A

not really; does not invade beyond the lamina propria

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8
Q

STEC will cause _______ color in sorbitol MacConkey’s agar

A

colorless because it does not ferment glucose

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9
Q

STEC is also known as EHEC and is associated with ____ (food)

A

beef patties

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10
Q

_____ colored colonies can be seen when rowing STEC on MacConkey’s agar

A

red-pink colored colonies

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11
Q

what are the characteristics of Shiga toxin? what shigella species can this be found in?

A
  • enterotoxic, neurotoxic, cytotoxic

- found in shigella dysenteriae type 1

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12
Q

what are some pathogenic mechanisms of EAEC

A
  • adherence
  • mucose production → biofilm formation
  • cytotoxin production
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13
Q

what are 3 life threatening conditions caused by STEC?

A
  1. Hemorrhagic colitis (3 days after ingestion)
  2. hemolytic uremic syndrome (5-13 days post diarrhea) and occurs in kids < 5 y/o
  3. TTP
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14
Q

Shiga toxin is encoded by _____

A

chromosomal genes

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15
Q

shigella ______ is seen in children less than 5 years old and in day care

A

sonnei (most common)

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16
Q

shigella species is broken up into 4 groups based on ______

A

O antigen

17
Q

how does shigella move from host cell to host cell?

A

aid of actin filaments; (F actin polymerization)

18
Q

what are the virulence factors of shigella?

A
  • O antigen (endotoxin)
  • exotoxin: neurotoxin that can cause meningismus, and coma, ulceration
  • NAD glycohydrolase: destroys all NAD in human cells → shuts down metabolism → cell death
19
Q

phagosome lysis is a characteristic of ______

A

shigella;
binds to M cell → ingested by macrophage/phagosome → phagosome lysis and macrophage apoptosis and replicates in the cytoplasm→ release of IL-1 and PMN transmigration → shigella migrates through disrupted tight junctions

20
Q

what is the enterotoxic effect of the Shiga toxin?

A
  • adheres to small intestine epithelium and blocks absorption of electrolytes, glucose and AA
  • watery diarrhea
21
Q

does E. coli ferment lactose?

A

YES

22
Q

EIEC utilizes ____ associated genes which code for ________

A

plasmid encoded genes that code for the outer protein that mediates invasion

23
Q

reservoirs of EHEC/STEC is _______

A

cattle and sheep

24
Q

other than H2S production, what other characteristic can help differentiate between shigella and salmonella

A

salmonella is motile while shigella is non motile

25
Q

can shigella ferment lactose?

A

NO

26
Q

shigella ______ is seen in gay men

A

flexneri

27
Q

EIEC has a low / high infective dose

A

VERY LOW (as small as 10 organisms)

28
Q

damage to _____ causes the formation of micorthrombi in _____ infection

A

RBC’s; STEC/EHEC infection

29
Q

_____ and _____ and inflammatory diarrhea causing agents THAT DO NOT invade the enterocytes

A
  • EAEC

- STEC

30
Q

Shiga cytotoxin binds to __________ which inhibits protein synthesis and causes cell death

A

60S ribosomal subunit

31
Q

EIEC is similar to _____

A

shigella

32
Q

which inflammatory diarrhea causing pathogens can have a complication of glomerulonephritis?

A
  • Shigella
  • Yersinia
  • campylobacter
33
Q

shigella is acid labile/stable

A

stable;

salmonella is acid labile

34
Q

STEC produces a ____ encoded cytotoxin (verotoxin)

A

phage

35
Q

how is shigella spread?

A
  • fecal oral; no known animal reservoir
36
Q

of the enterbacteriacae, which are NON LACTOSE fermenters

A

ShYPS
-shigella
- yersinia
(above two are non motile non lactose fermenters and non H2S producers)

  • Proteus
  • Salmonella
    (above two are motile, non lactose fermenters, H2S producers)
37
Q

EHEC produces ____ toxin

A

Shiga

38
Q

what is the function of AAF (aggregative adherence factor) in _____

A

EAEC;

it mediates attachment to the intestinal mucosa and triggers host inflammatory response

39
Q

EAEC is characterized by the presence of ________

A

AAF (aggregative adherence fimbriae)

PCM Exam 4 (44 decks)

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