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LECOM Microbiology MS1 > Virulence Factors (Exam 1) > Flashcards

Virulence Factors (Exam 1) Flashcards

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1
Q

What is a nosocomial infection

A

hospital or health associated place acquired infection

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2
Q

What can be the causes of nosocomial infection

A

endogenous or exogenous

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3
Q

What is an opportunistic infection

A

infection caused by a microorganism that does not usually cause a disease in a healthy individual

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4
Q

What is an endogenous source of infection

A

from person’s own microbiome

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5
Q

What is an exogenous source

A

outside of the person’s own microbiome

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6
Q

When will symptoms present in a patient with a nosocomial infection

A

48-72 hours after being admitted

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7
Q

What is virulence

A

ability of an organism to cause disease

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8
Q

What are virulence factors

A

products that the organism generates which enable it to survive and cause disease

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9
Q

What factors play into disease outcome

A

Person or host exposed
and
the microorganism

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10
Q

Is the outcome of exposure to an infectious agent the same for all who have been exposed

A

no

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11
Q

How does the person or host impact outcome of infection

A

immune system

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12
Q

How does the microorganism impact infection

A

number of microbes exposed

virulence of microbes

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13
Q

What are the steps in the infection process

A 
Entry
Adherence
Gaining Nutrients
Multiplying
Evading Host Immune
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14
Q

What are the different methods of human to human transmission of organism

A

vertical

horizontal

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15
Q

What is vertical transmission of organisms

A

from parent to child, generational

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16
Q

What is horizontal transmission

A

from human to human

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17
Q

What are methods of vertical transmission

A

in utero, during delivery, through breast milk, blood

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18
Q

What are methods of horizontal transmission

A

direct contact
Respiratory
Fomites

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19
Q

How is blood transmitted

A

vertical or horizontal

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20
Q

What are fomites

A

intermediate, inanimate object that can transmit an infectious disease/pathogen

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21
Q

What are examples of vector born transmission

A

mosquitoes: malaria, west nile
Ticks: borrelia: lyme disease

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22
Q

What is zoonosis transmission

A

an infection transmitted to a human from an infected animal

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23
Q

What are the different methods of zoonosis transfer

A

direct: eating animal, scratches, bites, fecal
indirect: through an arthropod vector

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24
Q

How does Salmonella, Shigella, and E. coli gain entry

A

ingestion

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25
Q

How does mycobacterium and legionella gain entry

A

inhalation

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26
Q

How does clostridium tetani gain entry

A

trauma

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27
Q

How does staph epidermidis, S. aureus gain entry

A

needle stick

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28
Q

How does borrelia, ehrlichia, rickettsia gain entrance

A

arthropod bite

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29
Q

How does neisseria, chlamydia gain entrance

A

sexual transmission

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30
Q

What are the possible outcomes after being exposed to a pathogen

A
  1. clear pathogen, no infection
  2. asymptomatic
  3. carrier and pass it on
  4. develop symptoms
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31
Q

What are acute infection characteristics

A

sudden onset, short term

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32
Q

What are chronic infection characteristics

A

long term, slow progression, may last a lifetime

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33
Q

What is the function of pili in colonization

A

adhesion to cells and tissue

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34
Q

What is the function of adhesins in colonization

A

tight binding to host cells

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35
Q

If the receptor on host is a sugar, what is the adhesin known as

A

lectin

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36
Q

What is the role of invasion proteins in colonization

A

host cellular actin rearrangement

forced phagocytosis of bacteria to get bacteria inside host. Move from one host to another cell

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37
Q

What structure allows specific attachment of cells to other cells

A

pili

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38
Q

What are the 3 main functions of pili

A

Movement
Adhering
Conjugation: transfer of DNA

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39
Q

What is a conjugation pilus

A

allows the transfer of DNA material between cells

hollow in center

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40
Q

What is a capsule

A

polysaccharide and water structure that surrounds the cell

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41
Q

What bacteria is the exception to having a polysaccharide capsule

A

Bacillus anthracis

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42
Q

What type of capsule does Bacillus anthracis have

A

Protein: amino acids

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43
Q

What are the functions of a capsule

A

protect
nutrients
adherence
prevents dehydration

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44
Q

What allows organisms to cross the blood brain barrier

A

capsule

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45
Q

What are examples of encapsulated bacteria

A 
Neisseria meningitidis
streptococcus pneumonia
klebsiella pneumoniae
haemophilus influenza b
pseudomonas aeruginosa
bacillus anthracis
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46
Q

What is a biofilm

A

community of microorganisms encases within an exopolysaccharide matrix attached to a solid surface or to each other

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47
Q

What makes cells in a biofilm less susceptible to antibiotics

A

antibiotics cannot easily penetrate the biofilm

cells in the biofilm grow more slowly

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48
Q

WHy are biofilms less susceptible to the immune system

A

immune system cannot penetrate through the biofilm

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49
Q

What are medical biofilms

A 
dental plaques
Urinary catheters
contact lenses
cystic fibrosis
endocarditis
otitis media
pacemakers
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50
Q

What is a common target within the GI tract for organisms that cause intestinal disease

A

Peyer patches: mucin layer thinner over M cells

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51
Q

What is the function of M cells

A

sample the luminal antigens and transport them to the lymphoid tissue below

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52
Q

What are examples of organisms that will invade through M cells

A 
Shigella
Salmonella
Listeria
Yersinia
Enteropathogenic E. coli
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53
Q

What are the steps of shigella flexneri invasion

A
  1. taken up by M cell
  2. Escapes from vaccule
  3. lyses m cell and infects epithelial cell
  4. replicates in cytosol of new cell
  5. polymerizes F actin
  6. propels to new cell
54
Q

What are direct ways in which a pathogen may cause damage

A

invade and disrupt cells

produce degradative enzymes and toxins

55
Q

What are indirect ways in which a pathogen may cause damage

A

trigger an immune response: host can damage itself

superantigen

56
Q

What does a superantigen cause

A

massive immune response resulting in shock and organ failure

57
Q

How might bacterial metabolism cause damage to host tissue

A

acids and gases from metabolism can be toxic

58
Q

What are examples of degradative enzymes that can causes damage to host tissues

A

streptococcus

pseudomonas

59
Q

What does streptococcus produce that is harmful to host

A

hyaluronidase

60
Q

What does pseudomonas produce that is harmful to host

A

elastase

61
Q

What is the effect of hyaluronidase

A

breaks down the polysaccharide component responsible for binding cells together

62
Q

What is the effect of elastase

A

breaks elastin down in the skin and CT

63
Q

What are exotoxins

A

toxins produced by the bacteria in extracellular environment

64
Q

What is an endotoxin

A

toxin attached to the bacterial cell

Lipopolysaccharide on gram negative bacteria

65
Q

How will incubation times differ between endo and exotoxins

A

exotoxins have a shorter incubation time than endotoxins

66
Q

How can exotoxins be designated

A

according to the location or tissue affected

67
Q

What is a neurotoxin

A

toxin that interferes with neural transmission

68
Q

What is an example of a neurotoxin

A

clostridium tetani: tetanus toxin

69
Q

What are enterotoxins

A

toxin that affects the intestines

70
Q

What is an example of an enterotoxin

A

vibrio cholerae: cholera toxin

71
Q

What are cytotoxins

A

toxins that destroy host cells

72
Q

What is an example of cytotoxins

A

clostridium perfringens: phospholipase C

73
Q

What are hemolysins

A

toxins that lyse RBC

74
Q

What is an example of hemolysin

A

strep pyogenes

75
Q

What are the different types of hemolysis

A

alpha
beta
gamma

76
Q

What occurs in beta hemolysis

A

complete breakdown of RBC

77
Q

What occurs in alpha hemolysis

A

partial breakdown of RBC, green halo

78
Q

What occurs in gamma hemolysis

A

cells grow, but do not lyse

79
Q

What are different toxins that can disrupt the cell membrane leading to cell lysis

A

phospholipase and ore-formin exotoxin

80
Q

What is an example of an exotoxin with two subunits

A

diphtheria toxin

81
Q

What is the A subunit of the toxin

A

active portion

82
Q

What is the B subunit of the toxin

A

receptor binding and transports the toxin into the cell

83
Q

What is the mode of action of the diptheria toxin

A

ADP-ribosyl transferase

84
Q

What does the ADP ribosyl transferase do

A

moves ADP to EF2 to inactivate the elongation factor and prevents host protein synthesis

85
Q

What other organism shares the similar mode of action as diptheria toxin

A

P. aeruginosa

86
Q

What is the mechanism of the cholera toxin

A

binds to Gs regulatory protein to activate adenylate cyclase to produce cAMP

87
Q

What does increased cAMP lead to

A

cell pumps Cl- and water into the intestinal lumen causing diarrhea

88
Q

What channel will the cholera toxin act on

A

CFTR cholride channel

89
Q

What botulinum toxins are pathogenic in humans

A

A, B, and E

90
Q

What is the mechanism of the botulism toxin

A

binds to the presynaptic terminal of a neuron to prevent release of ACh

91
Q

What does botulism toxin result in

A

flaccid paralysis and skeletal muscle weakness

92
Q

What is the mechanism of the tetanus toxin

A

binds to the presynaptic terminal of an inhibitory neuron preventing release of GABA

93
Q

What does tetanus toxin result in

A

spastic paralysis

94
Q

What will occur in response to a superantigen

A

cross linking of T cell receptors and MHC II molecules

95
Q

What is stimulated by a superantigen

A

cytokine production and inflammatory response; TSS and death

96
Q

What type of organism is more likely to elicit a superantigen response

A

gram positive organisms

97
Q

What is the name of the superantigen for staphylococcus aureaus

A

TSST1

98
Q

What is the name of the superantigen for Stap aureus

A

enterotoxins

99
Q

What is the superantigen for stretococcus pyogenes

A

streptococcal pyrogenic exotoxin A

100
Q

What type of organisms are endotoxins found in

A

gram negative

101
Q

What may happen as a result of a large amount of gram negative bacteria being killed

A

large amount of endotoxin is released

septic shock

102
Q

What type of organisms are responsible for toxic and septic shock

A

toxic: gram +
septic: gram -

103
Q

What is the mechanism of LPS

A

binds to CD14 and TLR4 on macrophages to induce Il-1 and TNF alpha production

activates complement
stimulates B cells to produce antibodies

104
Q

What cytokines will be released in response to LPS

A

TNF alpha

IL 1

105
Q

What are siderophores

A

iron scavenging molecules secreted by bacteria to acquire iron from the environement and bring it back to the bacterial cell being ingested

106
Q

What do siderophores bind to

A

Fe3+

107
Q

What are examples of siderophores

A

lactoferrin
transferrin
ferritin
hemin

108
Q

What is a type 3 secretion system

A

injects toxic proteins directly into host cell via syringe like apparatus

109
Q

What are examples of type 3 secretion

A

salmonella
pseudomonas
yersinia
ecoli

110
Q

What are the benefits of type 3 secretion systems

A

only produced when needed
doesn’t dilute toxins in environement
protects toxins from possible antibodies

111
Q

What are examples of organisms that evade host defenses by preventing phagocytosis

A

S pneumonia
H inflenzae
K pneumonia
ALL VIA CAPSULE

S pyogenes: M protein

112
Q

What are examples of organisms that evade host defenses by killing WBC

A

Staph and strepcoccus

113
Q

What do staph and strep produce to kill WBC

A

leukocidins

114
Q

What are examples of organisms that will produce enzymes to evade host defenses

A

staph aureas
streptococcus pneumoniae
strep pyogenes

115
Q

What enzyme does Staph aureas produce

A

coagulase

116
Q

What enzyme does streptoccoccus penumoniae produce

A

coagulase: coagulates fibrinogen forming abscesses

117
Q

What enzyme does streptococcus penumoniae produce

A

IgA protease

118
Q

What enzyme does streptococcus pyogenes produce

A

C5a protease

119
Q

What is antigenic variation

A

change structure of surface antigens therefore antibodies do not recognize bacteria

120
Q

How do organisms that grow intracellular evade the host defense

A

prevent phagosome lysosome fusion
escape phagosome
break down peroxide

121
Q

How are staph and strep differentiated

A

catalase test
strep negative
staph positive

122
Q

What is a coagulase test used to differentiate

A

between staph aureaus and other staph

123
Q

Where are genes that code for virulence factors located

A

chromosome
plasmids
bacteriophages
transposons

124
Q

What is a pathogenicity island

A

genes for toxin and secretory apparatus close together on the chromosome so they are produced efficiently

125
Q

Where will transposons move genes

A

from plasmid to chromosome or vice versa or from one site on chrom to another

126
Q

What is quorum sensing

A

bacterial interaction in which certain genes are turned on only when there are enough other bacteria in the area to make the response beneficial

127
Q

What type of chemical is used in quorum sensing

A

autoinducer

128
Q

What is an autoinducer

A

once the chemical reaches a high enough density it will bind to the promotor regions and turn on transcription followed by translation

129
Q

What are the steps in quorum sensing

A

bacteria produce and secrete chemical molecules

concentration of molecules increases with increasing bacterial density

when critical concentration of molecule is reached, bacteria alter gene expression

130
Q

What do chemical autoinducers mimic

A

human hormones

LECOM Microbiology MS1 (22 decks)

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