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Microbiology > Enteric Bacteria (EXAM III) > Flashcards

Enteric Bacteria (EXAM III) Flashcards

1
Q

Shape & 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

Peritrichous 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 in 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. Somen Ecoli 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 with 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 bloody diarrhea

A

Shiga

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23
Q

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

A

Pus in diarrhea

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24
Q

When enteric bacterial infection results in pus in diarrhea caused by neutrophil & inflammatory involvement:

A

Dysentery

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25
Q

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

A

Person-to-person
The “seven F’s”

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26
Q

What are the seven F’s of transmission?

A

Feces, food, fluids, fingers, flies, fomites & fornication

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27
Q

What is the enterobacterial common antigen:

A

Outer- and inner-core sugars

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28
Q

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

A

Enterobacterial common antigen

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29
Q

The LPS found in enterobacteria is also referred to as:

A

Heat-stable enterotoxin

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30
Q

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

A

Becomes important when considering sterilization

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31
Q

Is present in many bacteria like Yersinia, Salmonella, Shigella, Enteropathogenic EPEC (E. coli); also present other species like Pseudomonas and Chlamydia:

A

Type III secretion system

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32
Q

List the enterobacterial pathogenic species that utilize the a Type III secretion system:

A
  1. Yersinia
  2. Salmonella
  3. Shigella
  4. Enteropathogenic EPEC E. coli
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33
Q

List the non-enterobacterial pathogenic species that utilize the Type III secretion system:

A
  1. Pseudomonas
  2. Chlamydia
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34
Q

Describe the structure of a Type III secretion system:

A

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

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35
Q

What is the purpose of a Type III secretion system:

A

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

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36
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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37
Q

Translocated intimin receptor deliver through:

A

A type III secretion system

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38
Q

TIR

A

Translocated intimin receptor

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39
Q

What two pathogens both use a translocated intimin receptor that functions through a type III secretion system:

A
  1. Enterohemorrhagic E. coli (O157:H7)
  2. Enteropathogenic E. coli (EPEC)
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40
Q

List the modes of transmission of Escherichia coli:

A
  • Person-to-person
  • Contaminated food
  • Human & animal feces (no hand washing; insect vectors)
  • the 7 F’s
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41
Q

A cholera-like AB-exotoxin that performs ADP-ribosylation of G protein leading to increased cAMP levels resulting in loss of water & electrolytes & ultimately watery diarrhea:

A

Heat-labile enterotoxin “LT”

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42
Q

What is responsible for the condition commonly known as “Traveler’s diarrhea”

A

Heat-labile Enterotoxin “LT”

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43
Q

What type of toxin is the heat-labile enterotoxin “LT”?

A

A cholera-like AB-exotoxin

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44
Q

How does the virulence factor Heat-labile enterotoxin “LT” work?

A
  1. ADP-Ribosylation of G protein
  2. increase in cAMP levels
  3. loss of water and electrolytes

= watery diarrhea

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45
Q

What are two virulence factors of E. coli?

A
  1. Heat-labile enterotoxin “LT”
  2. Shiga toxin
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46
Q

An AB-exotoxin cytotoxin that functions through the inactivation of 60S ribosome subunit by removal of a specific adenine base from a nucleotide of 28s rRNA that results in the stop of translation, leading to cell death & blood diarrhea:

A

Shiga toxin

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47
Q

lt

A
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48
Q

What kind of toxin is Shiga toxin?

A

AB-exotoxin cytotoxin

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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

Foodborne 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 Shiga toxin may also be responsible for:

A

Hemolytic uremic syndrome resulting in kidney damage/failure

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52
Q

Describe how the virulence factor shiga toxin works:

A
  1. Inactivation of the 60s ribosome subunit by removal of a specific adenine base from a nucleotide of 28S rRNA
  2. Stop translation
  3. Cell death

= Bloody diarrhea

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53
Q

Describe the symptoms of Shigella Dysenteriae:

A
  1. Diarrhea with blood
  2. Intestinal cell invasion
  3. Apsoptosis of neutrophils to cause pus in diarrhea
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54
Q

What disease is responsible for the set of symptoms “diarrhea with blood” combined with intestinal cell invasion, apoptosis and neutrophilic resulting in pus and ultimately dysentery?

A

Shigella dysenteriae

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55
Q

What virulence factors of E. coli often have a seasonal basis to their incidence?

A

Shiga toxin

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56
Q

EHEC:

A

Enterohemorrhagic E. Coli (O157:H7)

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57
Q

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

A
  1. Bloody diarrhea
  2. Hemorrhagic colitis
  3. Hemolytic uremic syndrome
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58
Q

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

A

Replinish fluids
(antibiotics are contraindicated)

59
Q

How does UroPathogenic E. coli appear clinically?

A

Cystitis (bladder infection)

60
Q

For what E. coli strain are antibiotic treatment contraindicated?

A

EHEC (O157:H7)

61
Q

______ % of cystitis are due to an E. coli strain

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 shigellas 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

Inferior & lateral aspects; endocytosis

65
Q

In the process of shigella infection, after the shigella enter the lateral & inferior aspects of 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

The polymerize actin to form a tail that pushes the into the next cell

67
Q

In the process of shigella infection, what is the location of multiplication of shigellas?

A

Cytoplasm

68
Q

In the process of shigella infection, describe the role of neutrophils:

A

Cells infected with shigella die & 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 & abscess formation; induction of apoptosis

70
Q

Discuss the epidemiology of shigella:

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

What is generally the source of spread of shigella?

A

Humans generally the only source

72
Q

The 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 of shigella is responsible for:

A

Bloody, watery diarrhea; cell death

75
Q

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

A

Neutrophil death & 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 as its associated with:

A

High rate of mortality

79
Q

Salmonella is a species of:

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 include:

A

The meat, the outside of the egg and sometimes on the inside of the egg

83
Q

Many salmonella species are the cause of a:

A

Foodborne illness

84
Q

What bacteria species causes gastroenteritis:

A

Salmonella

85
Q

Describe the virulence factors of salmonella:

A
  1. Type III secretion
  2. Intracellular endoscope growth in macrophages
86
Q

Describe the virulence factors of S. Typhi serovars specifically:

A
  1. Invasion into different tissues and organs through macrophages
  2. Destruction of Peyer’s patches resulting in intestinal rupture
87
Q

Salmonellas ability use type III secretion induces:

A

Enteric epithelial uptake via M cells

88
Q

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

A

Secretion of protein that prevents phagosome-lysosome fusion

89
Q

Salmonella invasion of 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 a transient bacteremia

93
Q

Entrobacter species that is responsible for causing more systemic symptoms:

A

S. Typhi

94
Q

In S. Typhi, 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. Typhi following ingestion:

A

Small intestin

96
Q

If the S. Typhi spreads beyond the initial infection in the small intestine, it will travel via _____ to the ____

A

Lymphatics to the mesenteric lymph nodes

97
Q

Once the S. Typhi reaches the mesenteric lymph nodes via the lymphatics, it will travel via _____ to cause _____

A

Thoracic duct; transient (primary) bacteremia

98
Q

If S. Typhi infection causes transient (primary) bacteremia what will proceed:

A

Multiplication in macrophages in the liver, spleen & bone marrow

99
Q

When infection of S. Typhi processes to septicemia, what results?

A

Fever, kidney & 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 & ulceration of Peyers patches

103
Q

When S. Typhi causes inflammation & ulceration of Peyer’s patches this results in:

A

Diarrhea, hemorrhage & perforation

104
Q

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

A

Salmonella can be discharged into urine a couple weeks after initial infection

105
Q

What is the gram stain of enteric bacteria?

A

Gram negative

106
Q

Vibrio cholera is a type of _____ bacteria

A

Enteric

107
Q

In terms of virulence factors, vibrio cholera is considered:

A

Non-invasive (it doesn’t actually get inside of host cells, just infects them)

108
Q

Describe the gram stain and shape of vibrio cholera:

A

Gram negative; curved rods

109
Q

Vibrio cholera is found in:

A

Estuaries & marine environments

110
Q

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

A

A crab

111
Q

Vibrio cholera bacteria are _____ tolerant

A

Salt

112
Q

Virulence factors of vibrio cholera include:

A
  1. Toxin co-regulated pilus (TCP)
  2. Cholera toxin
  3. ST toxin
113
Q

The vibrio cholera toxin co-regulated pilus (TCP) is a virulence factor responsible for:

A

Adhesion to the small intestinal epithelia

114
Q

The vibrio cholera’s cholera toxin virulence factor is also called:

A

Heat-labile exotoxin “LT”

115
Q

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

A

Protein A causes cAMP rise, leading to watery diarrhea

116
Q

The additional virulence factor “ST” toxin contained by vibrio cholera is responsible for:

A

Raising cGMP levels, contributes to watery diarrhea

117
Q

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

A

Toxin co-regulated pilus (TCP)

118
Q

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

A

The raise in cGMP levels causes electrolytes & subsequent outlflow of water from epithelial cells

119
Q

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

A

Neuraminidase

120
Q

How does neuraminidase work to increase cholera toxin binding?

A

By cleaving sialic acid

121
Q

The cholera toxin is encoded in:

A

Bacteriophage genome called CTX-Phage

122
Q

The CTX-phage enters the cholera bacteria cell through:

A

A toxin co-regulated pilus

123
Q

TCP=

A

Toxin co-regulated pilus

124
Q

TCP production is induced within the _____ while production in other environments appears to be _____

A

Intestine; minimal

125
Q

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

A

ctxA & ctxB

126
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

127
Q

What are the common epidemic strain of vibrio cholera?

A

Server O1

128
Q

What is the newer strain of vibrio cholera that has caused recent epidemics?

A

Serovar O139

129
Q

List the virulence factors for vibrio cholera:

A
  1. Cholera toxin
  2. Toxin-coregulated pili
  3. Toxins
  4. Neuraminidase
130
Q

List the clinical features of infection with virbio cholera:

A

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

131
Q

What is the treatment for vibrio cholera infection?

A

Rehydration + electrolytes

132
Q

What is the epidemiology of vibrio cholera?

A
  1. Fecal transmission in developing countries (can get into drinking water)
  2. Under-cooked coastal crabs
133
Q

Bacteria that looks very similar to vibrio cholera:

A

Campylobacter jejune

134
Q

Describe the gram stain & shape of campylobacter jejune:

A

Gram negative & short “S” or curved/comma shaped rods

135
Q

A major virulence factor of campylobacter jejune includes:

A

Growth in intestinal tract

136
Q

The growth in the intestinal tract of campylobacter jejune functions to do what? (2)

A
  1. Invade intestinal epithelial cells or grow below the epithelial layer
  2. Inflammatory response
137
Q

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

A

Campylobacter jejune

138
Q

What type of reservoir is seen with campylobacter jejune?

A

Animal reservoir (intestinal)

139
Q

Because campylobacter jejune utilizes an animal reservoir this is called:

A

Zoonosis

140
Q

Describe the transmission of campylobacter jejune:

A

Transmission occurs through contaminated food (poultry, milk)

141
Q

In a study, what percent of raw chicken contained campylobacter?

A

89%

142
Q

How is campylobacter jejune typically resolved?

A

Without treatment in less than one week

143
Q

Campylobacter jejune infection being resolved without treatment creates:

A

Protective immunity

Microbiology (22 decks)

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