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MICROM 442 > Exam 3 Lecture 21 > Flashcards

Exam 3 Lecture 21 Flashcards

1
Q

True or false: Salmonella has many polar flagella

A

False: peretrichous flagella

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2
Q

What types of food has Salmonella been carried in?

A

leafy green veggies, malt&meal, chicken pot pie, ice cream (dairy), peanut butter

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3
Q

True or false: rapid use of antibiotics have increased the number and frequency of multi-drug resistant strains of Salmonella

A

true

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4
Q

What are some commonalities between Salmonella and Yersinia? (6)

A
  1. gram-negative rods
  2. facultative anaerobes
  3. can cause enteritis and systemic disease
  4. both use T3SS encoded on pathogenicity islands
  5. both adhere to M-cells of Peyer’s patches
  6. both interact w/ macrophages
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5
Q

True or false: Salmonella is usually only found in poultry

A

false; ubiquitous organism (has been found in seeds and spices)

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6
Q

There are over ___ different types of Salmonella, and ___ are associated with humans and mammals.

A

2250; 1435

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7
Q

True or false: the vast majority of salmonella serotypes are found in cold-blooded animals

A

false - warm blooded

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8
Q

Salmonella does not form ___ and does not ferment ____. (also: what is one exception?)

A

spores; lactose

S. Arizona is an exception

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9
Q

___ formation in indicator media is used to differentiate Salmonella

A

H2S

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10
Q

What are 4 commonly used medias to isolate Salmonella?

A
  1. SS agar
  2. Hektoen
  3. XLT
  4. MacConkey
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11
Q

What surface markers in Salmonella can we use for serotype description? (2)

A
  1. H-antigen

2. O-antigen

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12
Q

S. Typhi contains __-____, which is a polysaccharide capsule

A

Vi-antigen

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13
Q

True or false: there is no vaccine available for S. Typhi

A

False - there are 2 (Ts21a live oral vaccine, Vi-antigen injectable)

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14
Q

How long does the Vi-antigen vaccine last?

A

1-1.5 years

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15
Q

___ ___ that are present in media inhibit the growth of __-___ organisms like streptococcus and staphylococcus

A

bile salts; gram-positive

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16
Q

S. Arizona can look like:

A

E. coli

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17
Q

Symptoms of non-typhoidal Salmonella infection

A

fever, abdominal cramps, diarrhea (sometimes bloody)

occasionally establish localized infection like septic arthritis or progress to sepsis

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18
Q

How is non-typhoidal Salmonella transmitted?

A

ingestion of contaminated food, water, or contact with infected animals

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19
Q

Non-typhoidal Salmonella affects which age group? Who is most at risk for severe disease?

A

affects all ages; most at risk include infants, elderly, immunocompromised

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20
Q

50% of all salmonellosis cases in the US are due to either: (3)

A

S. Typhimurium, S. Enteritidis, S. Newport

likely due to the way poultry operations are run

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21
Q

An estimated 1.4 million cases of non-typhoidal Salmonella occur annually in the US, but this number is likely ___-____

A

under-reported

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22
Q

True or false: Salmonella is an enteric pathogen, and all spp are capable of infecting a wide variety of vertebrate hosts.

A

False - not all of them. S. Typhi only infects/replicates in humans

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23
Q

Salmonella is a ____ ____ ____, so it can survive both intra/extracellularly

A

facultative intracellular pathogen

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24
Q

Non-typhoidal Salmonella serotypes cause:

A

enteritis and occasional systemic infection

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25
Q

Typhoidal Salmonella cause:

A

enteric fever with little enteritis

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26
Q

True or false: Regarding S. Typhi, diarrhea is a common symptom along with enteric fever

A

False, usually don’t get diarrhea (little enteritis) but you can get enteric fever

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27
Q

Salmonella cannot survive anything below pH __. Therefore, in order to cause infection, the bacterial dose has to be ___.

A

4.5; large

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28
Q

Infectious dose of Salmonella is reduced if you eat ice cream because:

A

milk proteins buffer stomach acid

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29
Q

When ingested, Salmonella travel to the ___ ___. Uptake of Salmonella is mediated by _-___ and ____ cells

A

distial ileum; M-cells; CD18+

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30
Q

Salmonella invasion into M-cells is mediated by ____

A

SPI-1

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31
Q

Salmonella SPI-1 encodes?

A

Type 3 Secretion System effector proteins

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32
Q

Once across the intestinal epithelial cell layer, Salmonella encounters ____ ___ in the ____ ___.

A

phagocytic cells; lamina propria

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33
Q

Survival of Salmonella in professional phagocytic cells is needed for ____ ____. ___ gene products are needed for this step.

A

systemic infection; SPI-2

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34
Q

In the intestine, Salmonella expresses ___.

A

SPI-1

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35
Q

In macrophages, Salmonella expresses ___.

A

SPI-2

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36
Q

True or false: Salmonella have over 7 pathogenicity islands. Some have a plasmid

A

True

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37
Q

What is a hallmark of pathogenicity islands?

A

High A/T content (higher than the rest of the chromosome)

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38
Q

True or false: Expression of island genes are tightly controlled by multiple regulatory systems

A

true

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39
Q

True or false: Island genes are required for in vitro growth

A

False

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40
Q

___ is required for virulence of Salmonella by the oral route of infection for animal models and humans.

A

SPI-1

41
Q

SPI-2 encodes products that are injected into the cytoplasm of the ____ from inside the ____.

A

macrophage; phagosome

42
Q

What do SPI-2 effector proteins do?

A

interrupt the formation of enzyme complexes, preventing the accumulation of toxic products in the phagosome containing Salmonella

43
Q

What additional pathogenicity island does S. Typhi contain, and what does it encode?

A

SP17; encodes the Vi-antigen which is not found in other serotypes

44
Q

When Salmonella is invading intestinal epithelial cells, it induces …..

A

ruffling of target cell membrane, which facilitates bacteria to invade into the cell

45
Q

SPI-1 is needed to get into intestinal epithelial cells. What else does SPI-1 induce?

A

neutrophil migration

46
Q

When neutrophils migrate to site of Salmonella entry, what happens?

A

inflammation increases, which messed up chloride/water secretion, which is responsible for diarrhea

47
Q

SipA

A

needed for membrane ruffling by binding to actin filaments

48
Q

SipC

A

nucleates the actin and causes condensation of the actin to form ruffles

49
Q

SopD/B

A

act to promote chloride and fluid secretion

50
Q

Presence of intracellular bacteria is sensed by ___-____ ___

A

TLR5-recognition pathway

51
Q

Stimulation of TLR5 induces production of ___, which in turn stimulates the migration of ____ which causes ____ and ___ ___

A

IL8; neutrophils; inflammation; tissue damage

52
Q

Salmonella reside in the ____ of infected macrophage

A

phagosome

53
Q

Macrophages kill things via:

A

respiratory burst

54
Q

What is a respiratory burst?

A

rapid release of H2O2 and other ROS which is meant to kill bacteria

55
Q

Respiratory burst induces ____ ___ ___ that go on to damage __ and ___

A

secondary chemical compounds; DNA and protein

56
Q

True or false: SPI-2 prevents peroxides from being deposited into the phagosome containing salmonella

A

True

57
Q

Respiratory burst induces production of NO which is an ____

A

antimicrobial

58
Q

True or false: dumping of peroxides is the main mechanism of directly killing bacteria

A

false - peroxides just slow growth while NO kills bacteria

59
Q

True or false: proteins encoded on SPI-2 are easy to purify

A

False - very difficult because they’re meant to work from inside a membrane (they work inside to out)

60
Q

Salmonella ____ resident microbiota in the gut

A

outcompetes

61
Q

Salmonella use ____ and ____ as electron acceptors, thus grow even better in the presence of __

A

ethanolamine; tetrathionate; ROS

62
Q

definition of enteritis

A

inflammation of the intestinal lumen and induction of neutrophils

63
Q

definition of enteric fever

A

bacteria cross intestinal cell barrier and live in extra/intracellular sites

64
Q

True or false: Salmonella-mediated enteritis is not due to a toxin or enterotoxin

A

True - mediated by SPI-1 gene products

65
Q

Typhoid fever symptoms

A

fever, headache, constipation, malaise, chills, myalgia

66
Q

Which symptom of Typhoid fever is unique compared to other Salmonella infection symptoms?

A

constipation

67
Q

Where can S. Typhi be recovered from?

A

bloodstream, bone marrow, stool, urine

68
Q

S. Typhi cases mostly occur among:

A

travelers

69
Q

How long does S. Typhi illness last without treatment?

A

3-4 weeks with high death rate (12-30%)

70
Q

S. Typhi is transmitted through:

A

contaminated water or food, especially street vended foods

71
Q

True or false: almost all clinical isolates of S. Typhi produce Vi-antigen encoded on SPI-7

A

True

72
Q

How does Vi-antigen function in immune evasion?

A

shields S. Typhi frmo stimulating TLR5 and TLR4 signaling pathways of the innate immune system

73
Q

S. Typhi has over __ pseudogenes

A

200

74
Q

pseudogene definition

A

nonfunctional sections of DNA that no longer express anything

75
Q

Salmonella Typhi Infection Cycle (in order)

A
  1. ingestion of S. Typhi
  2. small intestine (leads to inflammation/ulceration)
  3. mesenteric lymph nodes
  4. transient bacteremia
  5. multiplication in macrophages
  6. gallbladder (which produces bile which circles back to small intestine)
76
Q

Yersinia spp cause similar disease as ___

A

Salmonella

77
Q

Which species of Yersinia are human pathogens and found in variety of animals and environments?

A

Y. enterocolitica; Y. pseudotuberculosis

78
Q

Major animal reservoir of Yersinia

A

swine

79
Q

Major source of Yersinia infection

A
  • pork products, raw and undercooked chitterlings (small intestine)
  • also milk products, turkey, chicken
80
Q

True or false: swine frequently succumb to infection by Yersinia

A

false

81
Q

Yersinia infection in humans mimics:

A

appendicitis

82
Q

Y. enterocolitica is acuired by:

A

ingestion of contaminated food

83
Q

Y. enterocolitica adheres to and invades:

A

M-cells of the Peyer’s patches (like Salmonella)

84
Q

Y. enterocolitica grows in:

A

regional lymph nodes, spleen, liver

85
Q

True or false: Y. enterocolitica commonly causes septicemia

A

False

86
Q

Which people are more susceptible to Y. enterocolitica mediated septicemia?

A

Immunocompromised people, people who are iron-overloaded, those who are being trated with deroxamine (iron chelation)

87
Q

Yersinia has ___ secretion system

A

Type 3

88
Q

True or false: once Yersinia has infected, they grow within macrophages

A

false - they grow extracellularly

89
Q

True or false: Y. enterocolitica can survive and resist antibody mediated killing

A

true

90
Q

Yersinia Virulence factors

A
  1. invasin
  2. Yops
  3. Yersiniabactin
91
Q

Function of Yersinia invasin

A

facilitates uptake by host cells

92
Q

Function of Yersinia Yops

A

produced on virulence plasmids, secreted into host cells via T3SS to disrupt host macrophage function and keep Yersinia from being phagocytosed

93
Q

Function of Yersinia Yersiniabactin

A

siderophore that binds and transports extracellular iron into the cell

94
Q

YopE and YopT

A

depolymerizes actin

95
Q

YopO

A

phosphorylates host proteins & disrupts cell signaling

96
Q

YopH

A

dephosphorylation of signal transduction proteins

97
Q

YopP

A

inhibits macrophage apoptosis and prevents TNF-alpha release

98
Q

Yersinia infection can lead to:

A

abscesses in the intestines at the M-cells

99
Q

True or false: temperature, calcium, and iron levels regulate virulence gene expression for Yersinia

A

true

MICROM 442 (26 decks)

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