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microbiology > Enteric bacteria- Exam III > Flashcards

Enteric bacteria- Exam III Flashcards

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1
Q

Shape and gram stain of enteric bacteria:

A

gram negative; bacilli

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2
Q

Some enteric bacteria are common members of:

A

human & animal flora

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3
Q

Some enteric bacteria are members of commensal groups that have become ____ due to ____

A

pathogenic due to acquired virulence factors

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4
Q

What are some of the acquired virulence factors causing some commensal enteric bacteria to become pathogenic?

A
  1. toxins from plasmids
  2. toxins from bacteriophages
  3. pathogenicity islands
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5
Q

Most enteric bacteria can be motile due to:

A

pertitrichous flagella (H-antigen)

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6
Q

Some enteric bacteria are non-motile such as:

A
  1. shigella
  2. klebsiella
  3. yersinia
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7
Q

Most enteric bacteria have ___ on the surface

A

surface pili

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8
Q

responsible for adherence and enteric bacteria:

A

fimbriae

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9
Q

responsible for plasmid conjugation in enteric bacteria:

A

sex pili

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10
Q

Some enteric species have ____ (such as K or Vi antigen)

A

capsules

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11
Q

Some enteric species have capsules such as:

A

K or Vi antigen

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12
Q

List the enteric bacterial species that contain capsules:

A
  1. most klebsiella species
  2. some enterobacter species
  3. some E. coli species
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13
Q

All enteric bacterial species contain:

A

outer membrane LPS

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14
Q

The outer membrane LPS found in all enteric bacterial species may be referred to as:

A

heat-stable endotoxin

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15
Q

All enteric bacterial species contain LPS (heat stable endotoxin) with:

A

enterobacterial common antigen and serotype-specific O-antigen

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16
Q

Because enteric bacteria are ____, they can survive when expelled in feces

A

facultative anaerobes

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17
Q

The enteric bacterial species that contain a capsule use this as an important:

A

virulence factor

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18
Q

Why do all enteric bacterial species contain an outer membrane LPS?

A

because they are gram negative bacteria

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19
Q

The characterization of various pathogenic E. coli strains is based on :

A

toxins produced

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20
Q

A lot of pathogenic enteric bacterial species result in:

A

GI issues

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21
Q

When enteric bacteria have a toxin like ____ toxin, it leads to watery diarrhea

A

cholera toxin

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22
Q

When enteric bacteria have a toxin like ___ toxin, it leads to blood diarrhea

A

shiga toxin

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23
Q

When enteric bacterial infection also involves neutrophils and inflammation, what may result?

A

pus in diarrhea

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24
Q

Pus in diarrhea is characteristic of:

A

dysentery

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25
Q

Transmission of pathogenic enteric bacterial species causing diarrhea, bloody diarrhea and dysentery are transmitted by:

A

person-to-person and the “seven F’s”= feces, food, fluids, fingers, flies, fomites and fornication

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26
Q

What is the enterobacterial common antigen?

A

Outer and inner core sugars

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27
Q

The outer and inner core sugars of enterobacterial species is referred to as:

A

enterobacterial common antigen

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28
Q

The LPS found in enteric bacteria is also referred to as:

A

Heat-stable enterotoxin

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29
Q

When must we consider that the LPS found in entrobacteria is a heat stable enterotoxin?

A

Becomes important when considering sterilization

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30
Q

Is present in many Bacteria like Yersinia, Salmonella, Shigella, Enteropathogenic EPEC (E. coli); also present in other species like pseudomonas and chlamydia:

A

Type III secretion system

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31
Q

List the enterobactrerial pathogenic species that utilize a type III secretion system:

A
  1. Yersinia
  2. Salmonella
  3. Shigella
  4. Enteropathogenic EPEC (E.coli)
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32
Q

List the Bacterial species that contain a Type III secretion system that are NOT enteric bacteria:

A

Pseudomonas and Chlamydia

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33
Q

Describe the structure of a Type III secretion system:

A

20-protein system that looks like a short hollow flagellum (needle)

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34
Q

What is the purpose of a Type III secretion system?

A

To inject a variety of species-specific toxins into host cells

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35
Q

Often times, _____ will be delivered from a bacterial cell (enteric bacteria) to a host cell via a Type III secretion system

A

virulence factors

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36
Q

In a type III secretion system, ____ binds to ____ to carry out the actions

A

Intimin binds to translocated intimin receptors

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37
Q

TIR:

A

Translocated initimin receptor

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38
Q

Translocated intimin receptors work for ____ and ____

A

Enterohemorrhagic E.coli & EPEC

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39
Q

E.coli transmission occurs through:

A

7F’s, person-to-person, contaminated food, human waste, and animal feces (no hand washing; insect vectors)

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40
Q

E. coli virulence factors include:

A
  1. Heat-labile enterotoxin “LT”
  2. Shiga Toxin
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41
Q

Describe Heat-labile enterotoxin “LT” (Virulence factor of e.coli)

A

Cholera-like AB-exotoxin

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42
Q

Cholera-like AB exotoxin:

A

Heat-labile enterotoxin “LT”

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43
Q

Describe the steps of heat-labile enterotoxins (found in E. coli) actions:

A
  1. ADP-ribosylation of G-protein
  2. increase camp levels
  3. loss of water & electrolytes
  4. Watery diarrhea
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44
Q

The heat-labile enterotoxin “LT” found in E. coli is responsible for what disease?

A

Traveller’s diarrhea

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45
Q

Describe shiva Toxin: (virulence factor of E. coli)

A

AB-exotoxin cytotoxin

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46
Q

AB-Exotoxin Cytotoxin:

A

Shiga toxin

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47
Q

Describe Shiga Toxins (found in E. coli) action:

A
  1. Inactivation of 60S ribosome subunit by the removal of a specific adenine base from a nucleotide of 28s rRNA
  2. Stops translation
  3. Cell death
  4. Bloody diarrhea
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48
Q

Describe

A
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49
Q

Foodborne enterotoxigenic ETEC E. coli may be responsible for _____ and specifically caused by ____.

A

watery diarrhea ; heat-labile enterotoxin “LT”

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50
Q

Food borne enterohemorrhagic EHEC E. coli O157:H7 may be responsible for ____ and specifically caused by ____.

A

bloody diarrhea; Shiga toxin

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51
Q

In addition to bloody diarrhea, shiva toxin may also be responsible for:

A

hemolytic uremic syndrome & kidney damage

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52
Q

Cholera-like AB-exotoxin responsible for ADP ribosylation of G-protein —> Increased cAMP levels —> loss of water & electrolytes —> watery diarrhea

A

heat-labile enterotoxin “LT”

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53
Q

AB-exotoxin cytotoxin responsible for inactivation of 60s ribosome subunit by removal of a specific adenine base from a nucleotide of 28S rRNA –> stopping translation –> cell death —> blood diarrhea

A

Shiga toxin

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54
Q

In _____ this set of symptoms “diarrhea with blood” is combined with intestinal cell invasion, apoptosis and neutrophillia leading to pus

A

shigella dysenteriae

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55
Q

Shiga toxin will often act on a:

A

seasonal basis

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56
Q

EHEC:

A

EnteroHemmorhagic E. coli (O157:H7)

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57
Q

EnteroHemmorhagic E. coli (O157:H7) clinically appears as:

A
  1. blood diarrhea
  2. hemorrhagic colitis
  3. hemolytic uremic syndrome
58
Q

What is the treatment for enterohemorrhagic E. coli (O157:H7) ?

A

Replenish fluids (antibiotics are contraindicated)

59
Q

How does Uropathogenic E. coli appear clinically?

A

Cystitis (bladder infection)

60
Q

For what E. coli strains are antibiotic treatments contraindicated?

A

EHEC

61
Q

____ % of cystitis can be due to E. coli strains

A

70-90%

62
Q

In the process of shigella infection: Shigellas are taken up by ___ and transported ___.

A

M cells; beneath the epithelium

63
Q

In the process of shigella infection: What happens to the shigella once below the epithelium?

A

Taken up by macrophages which will result in macrophage death and release of the shigellas

64
Q

In the process of shigella infection: The bacteria enter the ___ & ___ aspects of epithelial cells via induction of ____.

A

lateral and inferior; endocytosis

65
Q

In the process of shigella infection: After the shigella enter the lateral and inferior aspects of the epithelial cells via endocytosis, what happens to the endosomes?

A

Endosomes are quickly lysed leaving shigellas free in the cytoplasm

66
Q

In the process of shigella infection: How do the shigellas spread from cell to cell?

A

They polyermize actin to form a tail that pushes them into the next cells

67
Q

In the process of shigella infection: What is the location of shigella multiplication?

A

cytoplasm

68
Q

In the process of shigella infection: Describe the role of neutrophils

A

Cells infected with shigella die and slough off resulting in an intense response of acute inflammatory cells (neutrophils)

69
Q

In the process of shigella infection: In addition to the intense response of acute inflammatory cells, what may also occur in the final stages of shigella infection?

A

Bleeding and abscess formation, induction of apoptosis

70
Q

Discuss the epidemiology of shigella:

A
  • Transmission via fecal-oral route
  • Sometimes spread through contaminated food or water
  • Humans generally the only source
71
Q

What is generally the source of shigella?

A

Humans

72
Q

Virulence factors of shigella include:

A
  1. Shiga toxin
  2. Cell invasion
73
Q

What do the virulence factors of shigella ultimately lead to?

A

Dysentery

74
Q

The shiga toxin virulence factor is responsible for:

A

bloody watery diarrhea and cell death

75
Q

The cell invasion virulence factor of shigella bacteria is responsible for:

A

neutrophil death and pus formation

76
Q

S. enterica =

A

salmonella

77
Q

What illnesses may salmonella cause?

A
  1. enteric fever
  2. typhoid
78
Q

In extreme cases, salmonella may cause death as it is associated with:

A

high mortality

79
Q

Salmonella is a species of ____ bacteria

A

enteric bacteria

80
Q

What is the reservoir for s. enterica?

A

Human reservoir

81
Q

Aside from S. enterica using a human reservoir, many salmonella species have a ___ reservoir

A

poultry

82
Q

The poultry reservoir of many salmonella species includes

A

The meat, the outside of the egg and even the inside of the egg in some cases

83
Q

Many salmonella species are the cause of a ___ illness

A

food borne illness

84
Q

What bacterial species causes gastroenteritis?

A

salmonella

85
Q

Describe the virulence factors of salmonella:

A
  1. Type 3 secretion
  2. intracellular endosome growth in macrophages
86
Q

Describe the virulence factors of S. typhi serovars specifically:

A
  1. invasion into different tissues and organs via macrophages
  2. Destruction of Peyers patches leading to intestinal rupture
87
Q

Salmonellas ability to use type 3 secretion induces:

A

Enteric epithelial uptake via M cells

88
Q

The intracellular endosome growth in macrophages seen with salmonella species results in:

A

protein secretion that prevents phagosome lysosome fusion

89
Q

Salmonella invasion through intestinal epithelia occurs through:

A
  1. M cell uptake through ruffles
  2. Electrolyte release to lumen
  3. Release of inflammatory exudate
  4. Transport to lymph nodes/ transient bacteremia
90
Q

Uptake of salmonella into the intestinal epithelia occurs through the induction of membrane ruffling that occurs by the:

A

remodeling of the actin cytoskeleton

91
Q

When salmonella invoke membrane ruffling through the remodeling of actin cytoskeleton, this occurs through:

A

secretion of the virulence factors into the host cell

92
Q

What occurs when salmonella invade beyond the intestinal epithelium?

A

transport to lymph nodes resulting in transient bacteremia

93
Q

Enterobacter species that is responsible for causing more systemic symptoms:

A

S. typhii

94
Q

In S. typhii the bacterium can pass through the epithelia of the gut and spread by:

A

surviving inside phagocytes

95
Q

Where is the initial presence of S. typhii following ingestion:

A

small intestine

96
Q

If the S. typhi spreads beyond the initial infection in the small intestine it will travel via ____ to the ___.

A

lymphatics; mesenteric lymph nodes

97
Q

Once S. typhi reaches the mesenteric lymph nodes via the lymphatics, it will travel via ____ to cause ___.

A

thoracic duct to cause transient (primary) bacteremia

98
Q

If s. typhi infection causes transient (primary) bacteremia, what will proceed?

A

multiplication of macrophages in the liver, spleen and bone marrow

99
Q

When S. typhi progresses to septicemia, what results:

A

Fever, kidney and other organs infected

100
Q

Why is it significant if S. typhi infects the gallbladder?

A

following initial infection, individuals may maintain the bacteria in their gallbladder which can be shed in the feces and creates a very important carrier state of typhoid fever

101
Q

When s. typhi infects the gallbladder this results in:

A

Cholecystitis & carrier state

102
Q

Infection of s. typhi that is maintained in the small intestines leads to:

A

inflammation and ulceration of Peyers patches

103
Q

What is the significance of S. typhi getting into the kidney?

A

salmonella may be discharged into the urine following initial infection

104
Q

What is the gram stain of enteric bacteria?

A

gram NEGATIVE

105
Q

Vibrio cholera is a type of ____ bacteria

A

enteric

106
Q

In terms of virulence factors, vibrio cholera is considered:

A

non-invasive (doesn’t get inside the host cells)

107
Q

Describe the gram stain and shape of vibrio cholera:

A

gram NEGATIVE; curved rods

108
Q

Vibrio cholera is found in ____ & ___.

A

estuaries and marine environments

109
Q

Give an example of a host that may carry vibrio cholera:

A

crab

110
Q

Vibrio cholera are ____ tolerant

A

salt

111
Q

Virulence factors of vibrio cholera include:

A
  1. Toxin co-regulated pilus (tcp)
  2. cholera toxin
  3. ST toxin
112
Q

The vibrio cholera toxin co-regulated plus (tcp) is virulence factor responsible for:

A

adhesion to the small intestinal epithelia

113
Q

The vibrio cholera toxin virulence factor is also called:

A

heat-labile exotoxin “LT”

114
Q

What is cholera toxin (heat-labile exotoxin “LT” responsible for?

A

Protein A causes cAMP rise leading to watery diarrhea

115
Q

The addition virulence factor “ST” toxin contained in vibrio cholera is responsible for:

A

raising cGMP levels

116
Q

In vibrio cholera, responsible for adhesion to epithelium of small intestine:

A

tcp (toxin co-regulated pilus)

117
Q

The additional ST toxin in vibrio cholera contributes to watery diarrhea by:

A

raising cGMP levels causing electrolyte and subsequent outflow of water

118
Q

What can cause and increase in cholera toxin binding in vibrio cholera infections?

A

neuraminidase

119
Q

How does neuraminidase work to increase cholera toxin binding?

A

by cleaving sialic acid

120
Q

The cholera toxin is encoded in:

A

bacteriophage genome called CTXphage

121
Q

The CTXphage enters the bacterial cell through:

A

a toxin co-regulated pilus

122
Q

TCP=

A

Toxin coregulated pilus

123
Q

TCP production is induced with the ___, while production in other environments appears to be:

A

intestine; minimal

124
Q

What is responsible for encoding the proteins that comprise the cholera toxin?

A

ctxA & ctxB

125
Q

Describe the vaccine for cholera:

A

It is formalin killed meaning its non-pathogenic bacteria that has been inactivated but still a whole cell vaccine

126
Q

What are the common epidemic strain of v. cholera?

A

Serovar O1

127
Q

What is the newer strain of v. cholera?

A

serovar O139

128
Q

List the virulence factors of vibrio cholera:

A
  1. cholera toxin
  2. toxin- coregulated pili
  3. toxins
  4. neurominidase
129
Q

List the clinical features of infection with vibrio cholera:

A

severe watery diarrhea (disease is self-limiting as intestinal cells with surface bacteria are shed)

130
Q

What is the treatment for vibrio cholera infection?

A

rehydration + electrolytes

131
Q

What is the epidemiology of vibrio cholera:

A
  1. fecal transmission in developing countries (can get into drinking water)
  2. undercooked costal crabs
132
Q

bacteria that looks very similar to vibrio cholera:

A

campylobacter jejune

133
Q

Describe the gram stain and shape of campylobacter jejune:

A

gram negative & short S or curved/comma-shaped rods

134
Q

A major virulence factor of campylobacter jejune includes:

A

growth in intestinal tract

135
Q

The growth in the intestinal tract by campylobacter jejune functions to do what two things?

A
  1. invade intestinal epithelial cells or grow below the epithelial layer
  2. inflammatory response
136
Q

A more common, but less severe source of gastroenteritis in the US compared to E. coli and Salmonella:

A

campylobacter jejune

137
Q

What type of reservoir is seen with campylobacter jejune?

A

animal reservoir (intestinal)

138
Q

Because campylobacter jejune utilizes an animal reservoir, this is called:

A

zoonosis

139
Q

describe the transmission of campylobacter jejune:

A

Contaminated food (poultry/milk)

140
Q

What percent of raw chicken contained campylobacter in the study:

A

89%

141
Q

How is campylobacter typically resolved?

A

Without treatment in less than 1 week

142
Q

Campylobacter disease being resolved creates:

A

protective immunity

microbiology (24 decks)

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