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Immuno/micro final > Invasive gram-neg bacterial pathogens of GI tract > Flashcards

Invasive gram-neg bacterial pathogens of GI tract Flashcards

1
Q

Enterobacteriaceae and Vibronoaceae are both prolific colonizers of what?

A

mucosal surfaces

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2
Q

what is a mucosal surface?

A

Surface that interacts with air that has associated glands for secreting mucus.

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3
Q

what are the defenses of the mucosal surface?

A
  • Innate immunity
  • Adaptive immunity
  • Nonspecific barrier defenses
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4
Q

transmission of gram-negative mucosal pathogens: via what pathways?

A

the “seven F’s”

feces to mouth

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5
Q

what are the “7 F’s”?

A 
Feces
Food
Fluids
Fingers
Flies
Fomites
Fornication
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6
Q

what is the lowest range of inoculum size? (Shigella dysenteriae)

A

50-100 organisms

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7
Q

what are the natural barrier defenses for gram-negative pathogens?

A

A) secretory substances
B) anatomical and physiological
barriers
C) indigenous microbiota

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8
Q

what is the pH level of the gastrointestinal tract?

A

1-2 all the way up to 9

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9
Q

how does a Lysozyme (a.k.a muramidase) destroy a bacteria?

A

cleaves beta 1,4 glycosidic linkages between NAM and NAG

-only works on exposed murien (gram positive)

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10
Q

what is lactoferrin’s main function?

A

sequester iron

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11
Q

how does Cathelicidin work toward destroying a microbe?

A

Disrupts bacterial membranes of BOTH gram - and gram + bacteria

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12
Q

What do Defensins create on the target microbe?

A

pores

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13
Q

what are the 2 types of Defensins? where are they produced?

A

Alpha - produced by neutrophils and paneth cells (intestines)

Beta- produced by epithelial cells

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14
Q

How do pathogenic bacteria overcome these innate barrier defenses?

A

1) Acid resistance
2) Fimbriae/Pili
3) Bacterial structures

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15
Q

________ are an Important Component of Mucosal Immunity

A

Macrophages

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16
Q

Activation of pattern recognition receptors on macrophages also initiates the _______ _________

A

Inflammatory response

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17
Q

Which TLR will be most important for identifying gram-negative bacteria?

A

TLR4

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18
Q

Inflammatory cytokines, such as TNF-α can disrupt the _________ ______ between epithelial cells

A

Tight junctions

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19
Q

the Four species of Shigella are distinguished by what?

A

The O antigen

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20
Q

T/F: the Inoculum size of Shigella is very small

A

True

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21
Q

_____ _______ facilitates survival of Shigella through the stomach

A

Acid resistance

22
Q

where will Shigella multiply and colonize?

A

in the Colon

23
Q

Shigella microbes will travel through the mucosal surfaces, eventually entering what type of cell?

A

M cells

24
Q

how does Shigella enter the M cells?

A

using the outer membrane protein “invasion plasmid antigens”

25
Q

once it has entered the M cells, where is it released?

A

into the lamina propria- causes inflammatory response

26
Q

what response to Shigella actually causes illness?

A

inflammatory response as a result of macrophage activity

27
Q

Intracellular spread of Shigella facilitated by _______, an ATPase that causes ________

A

IcsA

actin polymerization

28
Q

what develops when invaded Shigella cells die and slough off?

A

Ulcer

29
Q

what immune cell can be found in the stool of people infected with Shigella?

A

Neutrophils

30
Q

All species of Shigella will induce an _______ ______ with leukocytes in the stool

A

inflammatory diarrhea

31
Q

which Shigella species induces a watery stool?

A

S. sonnei

32
Q

why is S. dysenteriae (Shigella) different from other forms of the genus?

A

it produces SHIGA TOXIN

33
Q

what does Shiga toxin do?

A

kills intestinal epithelium and endothelial cells

disrupts Na absorption

34
Q

Salmonella causes what 2 main diseases?

A

A) Gastroenteritis

B) Typhoid fever

35
Q

which species of Salmonella causes typhoid fever?

A

Salmonella typhi

36
Q

how is Salmonella transmitted?

A

fecal-oral transmission

can be between human or animal

37
Q

T/F: a relatively small inoculum is required for Salmonella

A

False- large inoculum required

38
Q

Salmonella is more _____-sensitive than shigellae

A

acid

39
Q

in Salmonella- a low pH induces the expression of at least 40 proteins found on what?

A

pathogenicity islands on large virulence plasmids

40
Q

when Salmonella approaches a host cell surface, it causes the increase of what within the cell?

A

Calcium

Ca2+

41
Q

the forced uptake of Salmonella into the host cell is known as what?

A

Microbe-directed phagocytosis

42
Q

unlike Shigella, Salmonella remains within ________ for many hours after entering

A

cell vesicles

43
Q

when salmonella is released to the lamina propria, what does it induce?

A

a loss of Na and Cl from the host cell

44
Q

Salmonella typhi will survive and grow within the _______

A

macrophages

45
Q

Salmonella typhi will travel from the gastrointestinal tract into the ____ ______

A

lymphatic system

46
Q

Salmonella typhi cannot survive in a _______ reservoir, meaning its strictly a what?

A
  • cannot survive in an animal reservoir

- strictly a human pathogen

47
Q

carriers of Salmonella typhi can often be _____

A

asymptomatic

-they have colonized gall bladders

48
Q

what is a unique property of the Salmonella strains that cause typhoid fever?

A

they multiply in macrophages in the:
A) liver
B) spleen
C) bone marrow

49
Q

Shigella and Salmonella are both invasive, so both are able to do what?

A

invade into the intestinal epithelial cells

both can invade host cells

50
Q

differences between Shigella and Salmonella:

A

1) Inoculum size (i.e., acid sensitivity)
2) Bacteremia (only Salmonella)
3) Species that cause severe disease are very dissimilar.

51
Q

Salmonella and Shigella species both cause what symptoms upon infection?

A 
Large Intestine
Small Volume of Stool 
Bloody Stool
Leukocytes in Stool
Tissue Ulcerations

Immuno/micro final (16 decks)

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