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MicroBiology Exam 2 > 2/27: mucosal surfaces, enterobacteriaceae-diarrheal diseases > Flashcards

2/27: mucosal surfaces, enterobacteriaceae-diarrheal diseases Flashcards

1
Q

Name 3 members of the enterobacteriaceae family that cause diarrhea

A
  1. e. coli
  2. salmonella species
  3. shigella species
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2
Q

Mucosal surface definition and examples

A

any surface that interacts with air and has glands that secrete mucous

examples: oral cavity, respiratory tract, repro/urinary tract, GI

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3
Q

What are the defenses of mucosal surfaces?

A

innate immunity, adaptive immunity and non-specific barriers (the cells themselves, mucous are physical barriers against infection)

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4
Q

E. Coli 0104:H4 OUtbreak
caused by ____
3500 causes, 800 caused by ____
32 people died, surprising because ____

A

caused by alfalfa sprouts, cucumbers
800 cases associated with hemolytic uremic syndrome
32 death is surpsing because this is rare for e. coli infections

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5
Q

E. Coli 0:26 outbreak
caused by ____
produced ____ (associated with bloody diarrhea)
mortality?

A

caused by chipotle
produced shiga toxin (associated w/ bloody diarrhea)
50 cases, half hospitalized, nobody died

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6
Q

Why do oral healthcare practitioners care about GI diseases?

A

they originate in the ORAL CAVITY due to fecal matter contamination
How does it get there? 7 F’s

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7
Q

What are the 7F’s?

A

how fecal matter contamination enters the oral cavity

feces
food
fluids
fingers
fomites
fornication
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8
Q

What is an inoculum size?

Low inoculum size range? spread by?

high inoculum size range? spread by?

A

inoculum size = amount of bacteria it takes to make someone sick (ID, infectious dose)

low ID: 50-100, usually spread by fomites or fingers so it doesn’t take as much

high ID: require millions of organisms to cause disease, so you would need bacteria to be in your food/drink

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9
Q

Name the 5 natural barrier defenses of the GI system

A
  1. natural anatomical and physiological properties
  2. acidity (and change in acidity) (stomach = 1-2, duodenum = 9)
  3. motility (chime moves through stomach and small intestine quickly, so bacteria need to be able to directly adhere to epithelium or mucous layer)
  4. mucous layer
  5. tight junctions hold epithelial cells together, prevent penetration of bacteria
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10
Q

normal flora in GI provides a physical barrier by ____

A

competing with pathogens for nutrients and oxygen

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11
Q

Name the 6 secretory antimicrobial compounds found in the GI system

A
  1. lysozymes
  2. lactoferrin
  3. cathelicidin
  4. alpha defensins
  5. beta defensins
  6. secretory Igs
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12
Q

Describe how lysozymes defend against bacterial invasion of GI tract

A

cleaves NAG and NAM linkage (although the murein isn’t directly exposed in gram Negs it still works)

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13
Q

Describe how lactoferrin defend against bacterial invasion of GI tract

A

sequesters/hides iron from bacteria

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14
Q

Describe how cathelicidin defend against bacterial invasion of GI tract

A

disrupts gram pos and gram neg membranes

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15
Q

Describe how alpha defensins defend against bacterial invasion of GI tract

made by ____

A

create pores in microbes

made by neutrophils and intestinal paneth cells

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16
Q

Describe how beta defensins defend against bacterial invasion of GI tract

made by ____

A

creates pores in microbes

made by epithelial cells

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17
Q

Describe how Igs defend against bacterial invasion of GI tract

A

secretes IgA specifically

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18
Q

What are the 3 ways that pathogenic bacteria overcome the innate barrier defenses of GI tract?

A
  1. acid resistance
  2. fimbriae/pilli
  3. bacterial structures
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19
Q

how does acid resistance help bacteria overcome innate barrier defenses in GI?

how does ID # play a role?

A

just enough acid resistance to get them through the stomach and into duodenum

microbes with low ID tend to be more acid resistant

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20
Q

How do fimbriae/pilli help bacteria overcome innate barrier defenses in GI?

A

helps microbe adhere to tissues

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21
Q

How do bacterial structures help bacteria overcome innate barrier defenses in GI?

A

bacteria can slightly change their cell membranes to evade bactericidal compounds, can incorporate cationic amino acids into cell membrane to reduce effect of cationic antimicrobial peptides

can sequester iron through siderophores

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22
Q

Macrophages are important for mucosa immunity because they recognize _____

TLR4 recognizes ____

A

macrophages recognize PAMPs and activate and kill many of the microbes

TLR4 recognizes LPS of gram negative bacteria

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23
Q

Describe the enteroibacteriaceae family general info

A

gram negative
range from coccobacilli to elongated rods
facultative aerobes
don’t form spores
ALL HAVE ENDOTOXIN LPS, some produce and secrete exotoxin

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24
Q

Enterobacteriaceae family all have cell wall components that are antigenic. 3 main types:

A
  1. O antigen (outer antigen, LPS)
  2. K antigen (polysaccharide capsule, not all have)
  3. H antigen (flagella)
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25
Q

What is a serotype?

Define e.coli O157:H7

A

variations within a bacterial species due to the difference in cell wall surface antigens

e.coli O157:H7 mean O-antigen LPS is type 157 and H-antigen flagella is type 7

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26
Q

Escherichia coli
most ferment ___
and produce ___

A

ferment lactose

produce indole

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27
Q

Escherichia coli serotypes are determined by ___ antigens

A

O, K, H

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28
Q

Most common type of pili on escherichia coli is ____

A

type 1

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29
Q

Type 1 pili on escherichia coli binds ____

A

d-mannose on epithelial cells

this has an on/off switch that turns ON in presence of ACID

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30
Q

The p pili on escherichia coli binds ____

A

digalactoside in urinary tract and in some erythrocytes

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31
Q

Other pili (not type 1 or p pili) on escherichia coli are common to _____ and bind to ____

A

common to diarheal strains

bind enterocytes

32
Q

What are the 3 main toxins associated with scherichia coli?

A
  1. alpha-hemolysin
  2. CNF (cytotoxic necrotizing factor)
  3. shiga toxin
33
Q

Alpha-hemolysin toxin of e.coli forms ___

34
Q

CNF (cytotoxic necrotizing factor) toxin of e.coli does what?

A

a-b toxin
produces g proteins
disrupts intracellular signaling

35
Q

Shiga toxin of e.coli does what?

A

a-b toxin

blocks protein synthesis by modifying ribosomes

36
Q

“Pathogenic e. coli is SELF LIMITING”

what does this mean?

A

bacteria are being flushed out and cell turnover is very high in the colon

so anything tha tattahces will be gone soon

37
Q

What are exceptions to “pathogenic e. coli is self limiting”

A

EAEC = diarhea for weeks
EPEC = can be chronic
EHEC and EIEC = bloody diarhea bc shiga toxin

38
Q

EPEC (enteropathogenic e. coli)
has ___ ID
causes ___
outbreaks occur in _____

A

high ID
affects SMALL INTESTINE
outbreaks in nurserys and developing countries

39
Q

What are the pili for EPEC (enteropathogenic e.coli)

A

Bfp (bundle-forming pili)

adheres to distal small intestine enterocytes

40
Q

EPEC (enteropathogenic e.coli) uses ___ secretion system

A

type III

injects e.coli secretion proteins into host cell

41
Q

EPEC (enteropathogenic e.coli) uses specific protein intimin-Tir

What does this do?

A

it is injected into the cell, goes to the membrane and allows bacteria to attach to the cell

this facilitates actin polymerization to form a “pedestal” for the bacteria to sit in

42
Q

What toxin does EPEC produce?

A

none.

doesn’t invade = doesn’t produce toxin

43
Q

EPEC likely causes diarrhea due to ____

A

defacement of microvili and tight junctions

44
Q 
EHEC (enterohemerrhagic e.coli)
has \_\_\_ ID
causes \_\_\_
\_\_\_ toxin
occurs in \_\_\_
A 
low id
shiga toxin
causes bloody diarrhea
occurs in developed countries
comes from animal products or vegetables/fruits due to cow manure fetilizer
45
Q

EHEC has shiga toxin which produces bloody diarrhea.

This can lead to _____

A

hemolytic uremic syndrome

46
Q

EIEC (enteroinvasive e.coli) is similar to ____ infection

A

similar to shigella infections

causes milder form of shigellosis

47
Q

EIEC (enteroinvasive e.coli) is acquired through ____

A

contaminated food/water

humans are the only reservoir

48
Q

EIEC (enteroinvasive e.coli) attaches to the host cell and…..

A

evades the endosome
multiplies inside cytoplasm
uses host cell actin to push through neighboring cells

49
Q

EAEC (enteroaggregative e.coli) leads to ____ that lasts ____

A

watery diarrhea that lasts up to 2 weeks

involved tight adherence of bacteria to epithelial cells in “stacked brick pattern”

50
Q

E.coli o104:h7 was which strain of e.coli?

51
Q

What is shigella?

A

specialized e.coli that only has O and K antigens

because no H antigen = no flagella (non motile)

52
Q

All species of shigalla are einvasive and multiply within ___

A

epithelial cells

53
Q

Do all forms of shigella produce the shiga toxin?

54
Q

What are the 4 species of shigella?

A

shigella dysenteriae - type 1, most serious, bloody diarrhea

shigella flexner - most common

shigella boydii

shigella sonnei - common, no bloody diarrhea

55
Q

Shigellosis
strictly infects ___
__ ID
___ resistant

A

strictly infects humans
ID = 10 low
acid resistant

56
Q

Shigellosis pathogenesis:

attaches to __ cells via ___

A

attaches to M cells via Ipa (invasion plasmid antigens)

57
Q

Shigellosis pathogenesis

Where in an M cell is it going to invade?

A

after shigella escapes the phagosome, it kills the macrophage.

now it can get to the LAMINA PROPRIA

58
Q

Shigellosis uses ___ secretion system

this helps inject ____ into what part of an enterocyte?

A

type III

helps inject IpaA and IpaD into BASOLATERAL SURFACE OF ENTEROCYTE

59
Q

Shigella injects IpaA and IpaD into ____ of enterocyte

A

basolateral surface of enterocyte

60
Q

How does shigella get from the basolateral surface of enterocyte into the enterocyte?

A

it properls itself into the enterocyte using host cytoskeletal rearrangement

61
Q

Once inside the enterocyte, how does shigella move around?

because no h antigen = no flagella = non motile

A

moves around using HOST ACTIN

62
Q

When shigella-invaded cells die and are sloughed off, what hapepns?

A

ulcer is formed at site of enterocyte death

diarrhea results from infalmmation

presents as CLASSIC DYSTENTERY (small volume diarrhea + leukocytes + RBC)

63
Q

Immunity against shigellosis?

A

produces antibodies

not protective over other serotypes

64
Q

How do you diagnose shigellosis?

A

stool culture or O-antigen agglutination

65
Q

Salmonella typhimurium causes ___

ID _____
acquired from ____

A

gastroenteritis

ID ranges from high to low
acquired from egg/poultry dishes

66
Q

Which is more acid sensitive: shigella or salmonella?

A

salmonella

67
Q

T/F: Salmonella typhimurium is transmitted via fecal-oral transmission from human to human

A

false

fecal-oral transmission from huamnd or animals

68
Q

Salmonella typhimurium bacteria attaches to ___ cells

uses ___ secretion system to inject proteins into host

A

M cell

Type III secretion system

69
Q

Salmonella typhimurium bacteria causes a ___ apperance of host cell

A

ruffled

as it uptakes the bacteria

70
Q

Salmonella typhimurium bacteria remains in the host cell to multiply for hours.

it is then released into the ____, stimulating a ____ response

A

lamina propria

stimulating an inflammatory response

bacteria is then taken up by phagocytes (mostly macrophages)

71
Q

If salmonella typhimurium escapes phagocytosis in the lamina propria, what does it do?

A

causes bacteremia

72
Q

T/F salmonella typhi is strictly human pathogen that can have asymptomatic carriers

73
Q

Where do salmonella typhi multiply?

how?

A

in macrophages

by inhibiting oxidative bursts

74
Q

What immune response oes salmonella typhi cause?

A

th1 and th2

75
Q

diagnosis of salmonella typhi?

A

stool sample or blood

to identify the O serogroup

MicroBiology Exam 2 (8 decks)

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