Chap 15 Flashcards
(231 cards)
1
Q
Pathogenicity
A
the ability to cause disease
2
Q
Virulence
A
the degree of pathogenicity
3
Q
Portals of entry for microorganisms
A
Mucous membranes
Skin
Parenteral route
4
Q
Parenteral route
A
Portal of entry beneath the skin and mucous membranes
5
Q
Moth pathogens have a preferred
A
portal of entry
6
Q
ID 50
A
infectious dose for 50% of a sample population
7
Q
ID 50 MEASURES
A
Measures virulence of a microbe
8
Q
LD50
A
lethal dose for 50% of a sample population
9
Q
LD50 MEASURES
A
POTENCY OF A TOXIN
10
Q
endospores
A
What are left behind when a bacteria is in an environment that it cant survive in. last hope for survival
11
Q
Which portal of entry is most likely to cause infection?
A
The one with the lower ID 50 because it needs less endosppores to cause disease
12
Q
adherence
A
pathogens attach to host tissues
13
Q
adhesins (ligands)
A
on the pathogen bind to receptors on the host cells
14
Q
receptors can be on
A
Glycocalyx
Fimbriae
15
Q
microbes form biofilms that are
A
communities that share nutrients
16
Q
capsules
A
Glycocalyx around the cell wall
17
Q
function of capsules
A
Impair phagocytosis
18
Q
Examples of microbes with capsules
A
Streptococcus pneumoniae—pneumonia
Haemophilus influenzae—pneumonia and meningitis
Bacillus anthracis—anthrax
Yersinia pestis—plague
19
Q
Cell wall components
A
- M protein
- Opa protein
- Waxy lipid
20
Q
M protein
A
resists phagocytosis
Streptococcus pyogenes
21
Q
Opa protein
A
allows attachment to host cells
Neisseria gonorrhoeae
22
Q
Waxy lipid
A
(mycolic acid) resists digestion
Mycobacterium tuberculosis
23
Q
Coagulases
A
coagulate fibrinogen
24
Q
Kinases digest
A
digest fibrin clots
25
Hyaluronidase
digests polysaccharides that hold cells together
26
Collagenase
breaks down collagen
27
IgA proteases:
destroy IgA antibodies
28
Antigenic variation
Pathogens alter their surface antigens (and antibodies are rendered ineffective)
29
How do invasins penetrate the host?
Surface proteins produced by bacteria that rearrange actin filaments of the cytoskeleton
Cause membrane ruffling
30
Use actin to move from one cell to the next
Shigella and Listeria
31
Survival inside phagocytes
Requirement for low pH in phagolysosome
Escape from phagosome before lysosomal fusion
Prevention of fusion of lysosome with phagosome
32
Fimbriae
Very specific to bacteria, strands that go out to help bacteria communicate and attach
33
Biofilms play a role in invading phagocytes
Biofilm bacteria more resistant to phagocytosis, shielded by extracellular polymeric substance (EPS) of biofilm
34
34
_____ is required for most pathogenic bacteria
Iron
35
Siderophores
proteins secreted by pathogens that bind iron more tightly than host cells
36
Direct damage disrupts
host cell function
37
Direct damage uses
host cell nutrients
38
Direct damage produces
waste products
39
Direct damage multiplies in
host cells and causes ruptures
40
Virulence factors
certain traits that help pathogens attach to and penetrate the host tissues and escape host defenses
41
Type of virulence factor that helps pathogen penetrate tissues
enzymes
42
Why do pathogens like to penetrate host tissues?
To have better access to nutrients and be able to reproduce
43
Examples of microbes that release hyaluronidase
Clostridium perfringens
Some streptococcus species
43
Collagen fibers are found in the base of
superficial tissues
44
Streptococcus and clostridium also secrete
Collagenase
45
What causes strep throat & necrotizing facitis
Streptococcus pyogenes
46
Secretes streptokinase that digests blood clots by breaking down fibrin proteins
Streptococcus pyogenes
47
fibrinolysin
aka streptokinase
48
staphylokinases
secreted by some staphylococcus do same as streptokinase
49
Streptococcus pyogenes & staphylococcus live on the
skin
50
Enteric pathogens
intestinal pathogens
51
Examples of enteric pathogens
Salmonella and Shigella
52
Etiologic agent of salmonellosis, typhoid and shigella
Salmonella
53
causes shigellosis
Shigella
54
Both can live within host cells as parasites
Salmonella and shigella
55
Flagella
on salmonella, helps it move in its environment
56
Toxins
poisonous substances produced by microorganisms
57
Toxins produce effects such as
fever, cardiovascular problems, diarrhea, and shock
58
Toxigenicity
ability of a microorganism to produce a toxin
59
Toxemia
presence of toxin in the host’s blood
60
Intoxications
presence of toxin without microbial growth
61
Exotoxins
Proteins produced and secreted by bacteria
Soluble in bodily fluids; destroy host cells and inhibit metabolic functions
62
Antitoxins
antibodies against specific exotoxins
63
Toxoids
inactivated exotoxins used in vaccines
64
Proteins produced inside pathogenic bacteria, most commonly gram-positive bacteria, as part of their growth and metabolism. The exotoxins are then secreted into the surrounding medium during log phase.
exotoxins
65
: toxic substances
released outside the cell
exotoxins
66
example of a gram-positive bacterium that produces exotoxins
Clostridium
botulinum
67
bacterial proteins that are secreted by a living organism into its surroundings
Exotoxins
68
What happens to exotoxins in a host?
exotoxins circulate and cause damage to host cells in various ways.
69
________ can cause severe damage or death at very low concentrations
Exotoxins
70
How can exotoxins be classified?
1. Location (neurotoxins)
2. Structure and function
3.
71
tetanus and botulism are caused by species of Clostridium that secrete
neurotoxins
72
Enterotoxins like those secreted by cholera bacterium can target
lining of intestinal tract
73
Cytotoxin
kills or seriously damages host cells in general.
74
Corynebacterium diptheriae is a bacterium that secretes a cytotoxin that
inhibits protein synthesis in host cells
75
Most exotoxins are proteins with two domains _ & _
A & B
76
A" domain of exotoxin is
an enzyme that has a particular function.
77
"B" domain of an exotoxin is
the binding component
78
B domain binds to
specific receptor (usually a carbohydrate ) on the host cell
79
Once the B domain attaches to the host cell,
the host cell uses endocytosis to bring the exotoxin inside.
80
Once the B domain opens a pore in the endosome...
this allows the A domain to escape into the cytosol
81
What happens when the A domain escapes into the cytosol?
It can inhibit protein synthesis or interfere with the host cytoskeleton. This usually results in the death of the host cell
82
Membrane disrupting toxins exert their effect without
entering the cytosol
83
How do membrane disrupting toxins exert their effect without entering the cytosol?
1. Form protein pores in the host plasma membrane.
2. Disrupt phospholipid portion of the membrane
84
Membrane disrupting toxins result in
The cell lysing
85
Superantigens
bacterial exotoxins that stimulate an excessive immune response.
86
Superantigens first cause a proliferation of
T cells
87
After causing a proliferation of T cells, then it
causes those T cells to release excessive amounts of cytokines
88
The cytokines can stimulate
fever, inflammation & shock. This intense immune response can lead to death.
89
The toxin secreted by staphylococcus aureus in food poisoning and Toxic shock syndrome is an example of a
Super antigen
90
contain an enzyme component (A part) and a binding component (B part)
AB toxins
91
Example of A-B toxin
Diphtheria toxin
92
Genotoxins
damage DNA (causing mutations, disrupting cell division, and leading to cancer)
93
lyse host cells by disrupting plasma membranes
Membrane-disrupting toxins
94
Leukocidins
kill phagocytic leukocytes
95
Hemolysins
kill erythrocytes by forming protein channels
96
Streptolysins
hemolysins produced by streptococci
97
cause an intense immune response due to release of cytokines from host cells (T cells)
Superantigens
98
Cause symptoms of fever, nausea, vomiting, diarrhea, shock, and death
superantigens
99
Lipid A
portion of lipopolysaccharides (LPS) of gram-negative bacteria
100
Lipid A released during
bacterial multiplication and when gram-negative bacteria die
101
Lipid A stimulates macrophages
macrophages to release cytokines
102
Lipid A causes
disseminated intravascular coagulation
103
LPS are part of
outer membrane of the cell wall of gram-negative bacteria (lipid A).
104
The endotoxins are liberated when
the bacteria die and the cell wall lyses, or breaks apart.
105
example of a gram-negative bacterium that produces endotoxins
Salmonella
typhimurium
106
Endotoxins are composed of
lipids that are part of the cell wall
107
First step of the pyrogenic response
A macrophage ingests a
gram-negative bacterium.
108
Step 2 of the pyrogenic response
Bacterium gets degraded in a vacuole.
Releases endotoxins that induce the macrophage to produce
cytokines, interleukin-1
(IL-1), and tumor necrosis
factor alpha (TNF-α).
109
Releases endotoxins that induce the macrophage to produce
cytokines, interleukin-1
(IL-1), and tumor necrosis
factor alpha (TNF-α).
110
Step 3 of pyrogenic response
cytokines are
released into the blood-
stream by the macrophages,
111
Through the macrophages, the cytokines travel to
to the
hypothalamus, the temperature
control center of the brain.
112
Step 4 of the pyrogenic response
The cytokines induce the
hypothalamus to produce
prostaglandins
113
Effect of releasing the prostaglandins
reset
the body's "thermostat" to a
higher temperature, producing
fever.
114
Limulus amebocyte lysate (LAL) assay
is used to test for endotoxins
115
Blood of horseshoe crabs contains
amebocytes
116
Amebocytes lyse in the presence of
endotoxin, producing a clot
117
"A" portion of the LPS in the outer membrane
Endotoxin
118
Endotoxins are only released when
The cell dies or during cell division
119
Interleukin 1 is a
protein messenger that ravels to the hypothalamus
120
Cause fever, an early sign of an infection
prostaglandins
121
Help stimulate phagocytosis, complement activation and antibody production by B lymphocytes
Endotoxins and interleukin 1
122
What happens when endotoxin is released in large amounts or within the bloodstream
serious and deadly effects.
123
Massive amounts of cytokines and interleukin 1 and tumor necrosis factor cause
1.loss of fluid from capillaries
2 vasodilation,
3.which lower BP. 4.Can lead to shock
124
cytokines and interleukin 1 also cause
coagulation, making it more severe. Most often occurs in bacterial sepsis
125
Bacterial sepsis is commonly caused by
E. Coli or meningococci in the blood stream or spinal fluid
126
metabolic product of growing the cell
exotoxins
127
Can be made by gram positive and gram negative bacteria
exotoxins
128
Bacterial source is gram negative bacteria
endotoxins
129
Present in LPS of outer membrane of cell wall and released with destruction of cell or during cell division
Endotoxins
130
Metabolic product of growing cell
Exotoxins
131
Proteins, usually with two parts A-B
exotoxins
132
Lipid portion (lipid A ) of LPS of outer membrane
Endotoxins
133
Specific for a particular cell structure or fucntion in the host (Mainly affects cell functions, nerves and GI tract)
Exotoxins
134
General such as fever, weaknesses, aches and shock, all produce same effects
endotoxins
135
Unstable, can usually be destroyed at 60-80 C except for staphylococcal enterotoxin
Exotoxins
136
Stable, can withstand autoclaving (121 C for one hour)
Endotoxins
137
High toxicity
Exotoxins
138
Low toxicity
Endotoxins
139
Fever producing: no
exotoxins
140
Fever producing: Yes
Endotoxins
141
Can be converted to toxoids to immunize against toxin; neutralized by antitoxin
Exotoxins
142
Not easily neutralized by antitoxin; therefore effective toxoids cannot be made to immunize against toxin
endotoxins
143
Small lethal dose
Exotoxins
144
Considerably larger lethal dose
Endotoxins
145
Gas gangrene, tetanus, botulism, diphtheria, scarlet fever, cyanobacterial intoxication
Representative Diseases
146
Typhoid fever, UTIs, Meningococcal meningitis
Endotoxins
147
Plasmids may carry genes for
1.toxins,
2.production of antibiotics,
3.enzymes
148
Lysogenic conversion
changes characteristics of a microbe due to incorporation of a prophage
149
Cytopathic effects (CPE)
visible effects of viral infection on a cell
150
Stopping cell synthesis
Cytopathic effects CPE
151
Causing cell lysosomes to release enzymes
Cytopathic effects CPE
152
Creating inclusion bodies in the cell cytoplasm
Cytopathic effects CPE
153
Inclusion bodies
non-living chemical compounds and by-products of cellular metabolism
154
Fusing cells to create a syncytium
Cytopathic effects CPE
155
Changing host cell function or inducing chromosomal changes
Cytopathic effects (CPE)
156
Inducing antigenic changes on the cell surface
Cytopathic effects (CPE)
157
Loss of contact inhibition in the cell, leading to cancer
Cytopathic effects (CPE)
158
Contact inhibition
animal cell movement and division stop as a result of contact with other cells.
159
Alpha and beta interferons produced by
virally-infected cells
160
Alpha and beta interferons protect
neighboring cells from viral infection
161
How do Alpha and beta interferons Protect neighboring cells from viral infection
1. Inhibit synthesis of viral proteins and host cell proteins
2. Kill virus-infected host cells by apoptosis
162
Some _______ have metabolic products that are toxic to human hosts
fungi
163
Can provoke an allergic response
fungi
164
Trichothecene toxins inhibit
Protein synthesis
165
fungal toxins that inhibit protein synthesis in eukaryotic cells.
Trichothecene
166
Two fungi that can cause skin infections, Candida albicans and Trichophyton (trik-ō-Fī-ton), secrete ________.
proteases
167
proteases
modify host cell membranes
168
Cryptococcus neoformans is a fungus that causes a type of meningitis; it produces a ________ that helps it resist phagocytosis.
capsule
169
prevent phagocytosis
capsule
170
Ergot
alkaloid toxins that cause hallucinations
171
Aflatoxin
carcinogenic toxin produced by Aspergillus
172
Ergot comes from
fungi
173
Aflatoxin comes from
Aspergillus which is fungi
174
Mycotoxins
produced by mushrooms and are neurotoxic
175
Phalloidin and amanitin are examples of
mycotoxins
176
produced by Amanita phalloides , commonly known as the deathcap. These neurotoxins are so potent that ingestion of the Amanita mushroom may result in death.
Phalloidin and amanitin
177
Presence of protozoa and their waste products causes
symptoms
178
Protozoa avoid host defenses by
1. Digesting cells and tissue fluids
2. Growing in phagocytes
3. Antigenic variation
179
helminths use host tissue for
growth
180
Helminths produce large masses which cause
cellular damage
181
Helminths produce waste products that
cause symptoms
182
saxitoxin made by
Made by algae,
183
People who eat the mollusks develop paralytic shellfish poisoning, with symptoms similar to botulism. Caused by which neurotoxin?
saxitoxin
184
Portals of exit
Route by which a pathogen leaves the body
185
pathogens leave the Respiratory tract via
Coughing and sneezing
186
pathogens leave the GI tract via
Feces and saliva
187
pathogens leave the Genitourinary tract via
Urine; secretions from the penis and vagina
188
Other portals of exit
Skin
Blood
189
How do pathogens leave the blood?
Arthropods that bite; needles or syringes
190
15-17 Which are the most often used portals of exit?
respiratory and gastrointestinal tracts.
191
When the balance between host and microbe tips in favor of the microbe, an infection or _______ results
disease
192
Learning these mechanisms of microbial pathogenicity is fundamental to understanding
how pathogens are able to overcome the host's defenses
193
portals of entry via mucous membranes include
1. Respiratory tract
2. Gastrointestinal tract
3. Genitourinary tract
4. Conjunctiva
194
Parenteral route
entry for pathogens by deposition directly into tissues beneath the skin and mucous membranes.
195
How does penetration or evasion of host defenses occur?
Capsules
Cell wall components
Enzymes
Antigenic variation
Invasins
Intracellular growth
196
Invasins
surface proteins that rearrange nearby actin filaments of the cytoskeleton.
197
Capsules increase virulence by
increases the virulence of pathogenic species. The capsule resists the host’s defenses by impairing phagocytosis
198
Bacteria get iron from the host using _________.
siderophores
199
_____ is required for the growth of most pathogenic bacteria. However, the concentration
Iron
200
the concentration of free iron in the human body is fairly low because
most of the iron is tightly bound to iron-transport proteins, such as lactoferrin, transferrin, and ferritin, as well as hemoglobin.
201
siderophores
bacterial iron-binding proteins
202
they take the iron away from iron-transport proteins by binding the iron even more tightly.
siderophores
203
Once the iron-siderophore complex is formed, it is taken up by
siderophore receptors on the bacterial surface
204
taken up by siderophore receptors on the bacterial surface. Then the iron is brought into the
bacterium
205
In some cases, the iron is released from the complex to enter
The bacterium
206
in other cases, the iron enters as part of
the complex
207
Direct damage toxins
endotoxins and exotoxins
208
After entering the host, most pathogens adhere to
host tissue,
penetrate or evade host defenses, and damage host tissues
209
Pathogens usually leave the body via specific portals of exit, which are
generally the same sites where they entered initially
210
M protein is found in
Streptococcus pyogenes
211
Opa protein is found in
Neisseria gonorrhoeae
212
Waxy lipid is found in
Mycobacterium tuberculosis
213
Exotoxins are ________ produced and secreted by _______
Proteins produced and secreted by bacteria
214
Exotoxins are soluble in
bodily fluids;
215
Exotoxins destroy
host cells
216
Exotoxins inhibit
metabolic functions
217
poisonous substances produced by microorganisms
Toxins
218
inactivated exotoxins used in vaccines
Toxoids
219
Once the host cell brings the exotoxin inside via phagocytosis?
B domain opens a pore in the endosome.
220
The ________ are then secreted into the surrounding medium during log phase.
exotoxins
221
Exotoxins are produced in
pathogenic bacteria, most commonly gram-positive bacteria
222
What happens after the bacterium gets degraded in a vacuole?
Releases endotoxins that induce the macrophage to produce
cytokines, interleukin-1
(IL-1), and tumor necrosis
factor alpha (TNF-α).
223
disseminated intravascular coagulation caused by
LIPID A
224
produced by mushrooms and are neurotoxic
Mycotoxins
225
alkaloid toxins that cause hallucinations
Ergot
226
carcinogenic toxin produced by Aspergillus
Aflatoxin
227
produced by mushrooms and are neurotoxic
Mycotoxins
228
Saxitoxin is what kind of toxin?
neurotoxin
229
- Paralytic shellfish poisoning is caused by
Saxitoxin
