Virulence Factors (Exam 1) Flashcards
1
Q
What is a nosocomial infection
A
hospital or health associated place acquired infection
2
Q
What can be the causes of nosocomial infection
A
endogenous or exogenous
3
Q
What is an opportunistic infection
A
infection caused by a microorganism that does not usually cause a disease in a healthy individual
4
Q
What is an endogenous source of infection
A
from person’s own microbiome
5
Q
What is an exogenous source
A
outside of the person’s own microbiome
6
Q
When will symptoms present in a patient with a nosocomial infection
A
48-72 hours after being admitted
7
Q
What is virulence
A
ability of an organism to cause disease
8
Q
What are virulence factors
A
products that the organism generates which enable it to survive and cause disease
9
Q
What factors play into disease outcome
A
Person or host exposed
and
the microorganism
10
Q
Is the outcome of exposure to an infectious agent the same for all who have been exposed
A
no
11
Q
How does the person or host impact outcome of infection
A
immune system
12
Q
How does the microorganism impact infection
A
number of microbes exposed
virulence of microbes
13
Q
What are the steps in the infection process
A
Entry Adherence Gaining Nutrients Multiplying Evading Host Immune
14
Q
What are the different methods of human to human transmission of organism
A
vertical
horizontal
15
Q
What is vertical transmission of organisms
A
from parent to child, generational
16
Q
What is horizontal transmission
A
from human to human
17
Q
What are methods of vertical transmission
A
in utero, during delivery, through breast milk, blood
18
Q
What are methods of horizontal transmission
A
direct contact
Respiratory
Fomites
19
Q
How is blood transmitted
A
vertical or horizontal
20
Q
What are fomites
A
intermediate, inanimate object that can transmit an infectious disease/pathogen
21
Q
What are examples of vector born transmission
A
mosquitoes: malaria, west nile
Ticks: borrelia: lyme disease
22
Q
What is zoonosis transmission
A
an infection transmitted to a human from an infected animal
23
Q
What are the different methods of zoonosis transfer
A
direct: eating animal, scratches, bites, fecal
indirect: through an arthropod vector
24
Q
How does Salmonella, Shigella, and E. coli gain entry
A
ingestion
25
How does mycobacterium and legionella gain entry
inhalation
26
How does clostridium tetani gain entry
trauma
27
How does staph epidermidis, S. aureus gain entry
needle stick
28
How does borrelia, ehrlichia, rickettsia gain entrance
arthropod bite
29
How does neisseria, chlamydia gain entrance
sexual transmission
30
What are the possible outcomes after being exposed to a pathogen
1. clear pathogen, no infection
2. asymptomatic
3. carrier and pass it on
4. develop symptoms
31
What are acute infection characteristics
sudden onset, short term
32
What are chronic infection characteristics
long term, slow progression, may last a lifetime
33
What is the function of pili in colonization
adhesion to cells and tissue
34
What is the function of adhesins in colonization
tight binding to host cells
35
If the receptor on host is a sugar, what is the adhesin known as
lectin
36
What is the role of invasion proteins in colonization
host cellular actin rearrangement
forced phagocytosis of bacteria to get bacteria inside host. Move from one host to another cell
37
What structure allows specific attachment of cells to other cells
pili
38
What are the 3 main functions of pili
Movement
Adhering
Conjugation: transfer of DNA
39
What is a conjugation pilus
allows the transfer of DNA material between cells
| hollow in center
40
What is a capsule
polysaccharide and water structure that surrounds the cell
41
What bacteria is the exception to having a polysaccharide capsule
Bacillus anthracis
42
What type of capsule does Bacillus anthracis have
Protein: amino acids
43
What are the functions of a capsule
protect
nutrients
adherence
prevents dehydration
44
What allows organisms to cross the blood brain barrier
capsule
45
What are examples of encapsulated bacteria
```
Neisseria meningitidis
streptococcus pneumonia
klebsiella pneumoniae
haemophilus influenza b
pseudomonas aeruginosa
bacillus anthracis
```
46
What is a biofilm
community of microorganisms encases within an exopolysaccharide matrix attached to a solid surface or to each other
47
What makes cells in a biofilm less susceptible to antibiotics
antibiotics cannot easily penetrate the biofilm
cells in the biofilm grow more slowly
48
WHy are biofilms less susceptible to the immune system
immune system cannot penetrate through the biofilm
49
What are medical biofilms
```
dental plaques
Urinary catheters
contact lenses
cystic fibrosis
endocarditis
otitis media
pacemakers
```
50
What is a common target within the GI tract for organisms that cause intestinal disease
Peyer patches: mucin layer thinner over M cells
51
What is the function of M cells
sample the luminal antigens and transport them to the lymphoid tissue below
52
What are examples of organisms that will invade through M cells
```
Shigella
Salmonella
Listeria
Yersinia
Enteropathogenic E. coli
```
53
What are the steps of shigella flexneri invasion
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
What are direct ways in which a pathogen may cause damage
invade and disrupt cells
| produce degradative enzymes and toxins
55
What are indirect ways in which a pathogen may cause damage
trigger an immune response: host can damage itself
superantigen
56
What does a superantigen cause
massive immune response resulting in shock and organ failure
57
How might bacterial metabolism cause damage to host tissue
acids and gases from metabolism can be toxic
58
What are examples of degradative enzymes that can causes damage to host tissues
streptococcus
| pseudomonas
59
What does streptococcus produce that is harmful to host
hyaluronidase
60
What does pseudomonas produce that is harmful to host
elastase
61
What is the effect of hyaluronidase
breaks down the polysaccharide component responsible for binding cells together
62
What is the effect of elastase
breaks elastin down in the skin and CT
63
What are exotoxins
toxins produced by the bacteria in extracellular environment
64
What is an endotoxin
toxin attached to the bacterial cell
Lipopolysaccharide on gram negative bacteria
65
How will incubation times differ between endo and exotoxins
exotoxins have a shorter incubation time than endotoxins
66
How can exotoxins be designated
according to the location or tissue affected
67
What is a neurotoxin
toxin that interferes with neural transmission
68
What is an example of a neurotoxin
clostridium tetani: tetanus toxin
69
What are enterotoxins
toxin that affects the intestines
70
What is an example of an enterotoxin
vibrio cholerae: cholera toxin
71
What are cytotoxins
toxins that destroy host cells
72
What is an example of cytotoxins
clostridium perfringens: phospholipase C
73
What are hemolysins
toxins that lyse RBC
74
What is an example of hemolysin
strep pyogenes
75
What are the different types of hemolysis
alpha
beta
gamma
76
What occurs in beta hemolysis
complete breakdown of RBC
77
What occurs in alpha hemolysis
partial breakdown of RBC, green halo
78
What occurs in gamma hemolysis
cells grow, but do not lyse
79
What are different toxins that can disrupt the cell membrane leading to cell lysis
phospholipase and ore-formin exotoxin
80
What is an example of an exotoxin with two subunits
diphtheria toxin
81
What is the A subunit of the toxin
active portion
82
What is the B subunit of the toxin
receptor binding and transports the toxin into the cell
83
What is the mode of action of the diptheria toxin
ADP-ribosyl transferase
84
What does the ADP ribosyl transferase do
moves ADP to EF2 to inactivate the elongation factor and prevents host protein synthesis
85
What other organism shares the similar mode of action as diptheria toxin
P. aeruginosa
86
What is the mechanism of the cholera toxin
binds to Gs regulatory protein to activate adenylate cyclase to produce cAMP
87
What does increased cAMP lead to
cell pumps Cl- and water into the intestinal lumen causing diarrhea
88
What channel will the cholera toxin act on
CFTR cholride channel
89
What botulinum toxins are pathogenic in humans
A, B, and E
90
What is the mechanism of the botulism toxin
binds to the presynaptic terminal of a neuron to prevent release of ACh
91
What does botulism toxin result in
flaccid paralysis and skeletal muscle weakness
92
What is the mechanism of the tetanus toxin
binds to the presynaptic terminal of an inhibitory neuron preventing release of GABA
93
What does tetanus toxin result in
spastic paralysis
94
What will occur in response to a superantigen
cross linking of T cell receptors and MHC II molecules
95
What is stimulated by a superantigen
cytokine production and inflammatory response; TSS and death
96
What type of organism is more likely to elicit a superantigen response
gram positive organisms
97
What is the name of the superantigen for staphylococcus aureaus
TSST1
98
What is the name of the superantigen for Stap aureus
enterotoxins
99
What is the superantigen for stretococcus pyogenes
streptococcal pyrogenic exotoxin A
100
What type of organisms are endotoxins found in
gram negative
101
What may happen as a result of a large amount of gram negative bacteria being killed
large amount of endotoxin is released
| septic shock
102
What type of organisms are responsible for toxic and septic shock
toxic: gram +
septic: gram -
103
What is the mechanism of LPS
binds to CD14 and TLR4 on macrophages to induce Il-1 and TNF alpha production
activates complement
stimulates B cells to produce antibodies
104
What cytokines will be released in response to LPS
TNF alpha
| IL 1
105
What are siderophores
iron scavenging molecules secreted by bacteria to acquire iron from the environement and bring it back to the bacterial cell being ingested
106
What do siderophores bind to
Fe3+
107
What are examples of siderophores
lactoferrin
transferrin
ferritin
hemin
108
What is a type 3 secretion system
injects toxic proteins directly into host cell via syringe like apparatus
109
What are examples of type 3 secretion
salmonella
pseudomonas
yersinia
ecoli
110
What are the benefits of type 3 secretion systems
only produced when needed
doesn't dilute toxins in environement
protects toxins from possible antibodies
111
What are examples of organisms that evade host defenses by preventing phagocytosis
S pneumonia
H inflenzae
K pneumonia
ALL VIA CAPSULE
S pyogenes: M protein
112
What are examples of organisms that evade host defenses by killing WBC
Staph and strepcoccus
113
What do staph and strep produce to kill WBC
leukocidins
114
What are examples of organisms that will produce enzymes to evade host defenses
staph aureas
streptococcus pneumoniae
strep pyogenes
115
What enzyme does Staph aureas produce
coagulase
116
What enzyme does streptoccoccus penumoniae produce
coagulase: coagulates fibrinogen forming abscesses
117
What enzyme does streptococcus penumoniae produce
IgA protease
118
What enzyme does streptococcus pyogenes produce
C5a protease
119
What is antigenic variation
change structure of surface antigens therefore antibodies do not recognize bacteria
120
How do organisms that grow intracellular evade the host defense
prevent phagosome lysosome fusion
escape phagosome
break down peroxide
121
How are staph and strep differentiated
catalase test
strep negative
staph positive
122
What is a coagulase test used to differentiate
between staph aureaus and other staph
123
Where are genes that code for virulence factors located
chromosome
plasmids
bacteriophages
transposons
124
What is a pathogenicity island
genes for toxin and secretory apparatus close together on the chromosome so they are produced efficiently
125
Where will transposons move genes
from plasmid to chromosome or vice versa or from one site on chrom to another
126
What is quorum sensing
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
What type of chemical is used in quorum sensing
autoinducer
128
What is an autoinducer
once the chemical reaches a high enough density it will bind to the promotor regions and turn on transcription followed by translation
129
What are the steps in quorum sensing
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
What do chemical autoinducers mimic
human hormones
