Final Exam Flashcards
(133 cards)
1
Q
what is the larger organism that supports the survival and growth of a pathogenic microorganism?
A
host
2
Q
a microbe growing and multiplying within a host - may or may not result in overt disease
A
infection
3
Q
any change from a state of health - part or all of the host is incapable or carrying on normal functions due to presence of pathogen or its products
A
infectious disease
4
Q
any organism that causes disease
A
pathogen
5
Q
causes disease by direct interaction with healthy host
A
primary pathogen
6
Q
may be part of normal microbiota and causes disease when the host is immunocompromised
A
opportunistic pathogen
7
Q
ability of a pathogen to cause disease
A
pathogenicity
8
Q
degree of harm (pathogenicity) inflicted on its host
A
virulence
9
Q
remain in tissues and fluids but never enter host cells during disease
A
extracellular pathogens
10
Q
grown and multiply within host cells
A
intracellular pathogens
11
Q
reside within cells of the host or in the environment but can also be grown in pure culture without host cell support
A
facultative intracellular pathogens
12
Q
only grow inside host cells
A
obligate intracellular pathogens
13
Q
time between pathogen entry and development of signs and symptoms
A
incubation period
14
Q
mild, non-specific signs and symptoms
A
prodromal stage
15
Q
disease is most severe and display signs and symptoms
A
illness period
16
Q
recovery stage
A
convalescence
17
Q
objective changes that can be directly observed and measured (fever, rash)
A
signs
18
Q
subjective changes (pain, loss of appetite) - term often used in broader score in clinical signs
A
symptoms
19
Q
set of characteristic signs and symptoms for a disease
A
disease syndrome
20
Q
the host provides the pathogen …
A
protection
nutrients
energy to use
21
Q
infectious agents develop mechanisms to access and exploit ____
A
hosts
to survive they must also devise methods to move on to a better environment or host when necessary
22
Q
factors that affect the success of transmission
A
- virulence of organism
- number of invading organisms
- presence of adhesion and invasion factors
23
Q
organism outcompetes the ____ _____ for resources and survive host defense mechanisms
A
resident microbiota
24
Q
disease ensues when …
A
organism produces molecules that directly damage host cells or stimulates host immune cells to destroy infected tissue.
25
natural environment location in which the pathogen normally resides
reservoir
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organism that spread disease from one host to another (ticks, mosquitos, fleas)
vector
27
5 main routes of pathogen transmission
- airborne
- contact
- vehicle
- vector-borne
- vertical transmission
28
efficiency of transmission _____ with extensive multiplication
increases
29
if a pathogen can live outside of a host they might be
more virulent
30
pathogen must make contact with appropriate host tissue
tropism
31
how are droplets in airborne transmission classified
direct transmission - placed under force (saliva, mucus)
32
how are droplet nuceli in airborne transmission classified
indirect transmission
result from evaporation of the larger droplets
may remain airborne for hours or days and can travel long distances
33
how are dust particles in airborne transmission classified
indirect transmission
aerosolized - smaller than 1 um, can be dispersed way further
can survive long periods outside the host and can lead to hospital acquired infections
34
host touching source or reservoir of the pathogen
contact transmission
35
2 types of contact transmission
direct contact - person to person
indirect contact - inanimate object (fomite) that transfers infectious agents between hosts
36
materials that indirectly transmit pathogens
vehicle transmission
37
a single source containing pathogens can contaminate a common vehicle that cases multiple infections
dog bowl
38
vector borne transmission pathogens benefit because
extensive reproduction and spread between hosts
- highly virulent and cause diseases such as malaria, lymes, west nile
- important that pathogens do not harm their vectors
39
external (mechanical) transmission
passive carriage of pathogen on body of vector
no growth of pathogen during transmision
40
internal transmission
- carried within vector
- harborage transmission - pathogen does not undergo changes within vector
- biologic transmission - pathogen undergoes changes within vector
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occurs when unborn child acquires a pathogen from infected mother
vertical transmission
42
babies born with an infectious disease are said to have
a congenital infection
43
the number of microbes required to cause disease in 50% of the inoculated hosts
infectious dose
44
dose that kills 50% of a group of experimental hosts within a specific period
lethal dose
influenced by susceptibility of the host
45
portal of entry
skin, respiratory, gastrointestinal, urogenital, conjunctiva of eye
46
attachment of microbe to ____ ____ is first in adherence and invasion
target cell
47
establish a state of microbial replication on or within host
colonization
48
adherence structures
pilli
fimbriae
membrane and capsular materials
specialized adhesion molecules on microbes cell surface
49
ability to create a discrete point of infection
infectivity
50
ability to spread to adjacent tissues
invasiveness
51
penetration can be active or passive. describe active
production of lytic substances that alter host tissue
- attack the extracellular matrix and basement membranes of integuments and intestinal linings
- degrade carbohydrate - protein complexes between cells
- disrupt the host cell surface
52
penetration can be active or passive. describe passive
not related to pathogen itself (that is skin, lesions, insect bites, wounds)
53
presence of viable bacteria in the blood
bacteremia
54
bacterial or fungal toxins in the blood
septicemia
55
_______ ______ is noninvasive because it does not spread from one tissue to another, but toxins become blood borne
clostridium tetani (tetanus)
56
_________ _______ and ______ _______ also produce toxins and are highly invasive
bacillus anthracis (anthrax) and Tersinia pestis (plague)
57
__________ span the spectrum of virulence factors and invasiveness
streptococcus
58
formation of actin tail by intracellular bacterial pathogens
invasion
59
actin tail propels bacteria to the ______ ______ _______ where it forms a protrusion
host's cell surface
60
_____ is engulfed by adjacent cell - evades immune response
protrusion
61
strategies to evade host immune response
- production of decoy proteins to bind antimicrobial proteins
- mutate cell surface proteins
- reduce the number of cell surface proteins
- phage variation - switch among different genes that encode similar proteins - alter pilli protein sequence and expression
- produce proteases that degrade host proteins
- produce special proteins that interfere with the host's ability to detect and remove them
- cause host cell fusion to spread without exposure to immune system
62
suppressing host immune response
- infect cells of the immune system and diminish their function while ensuring their own survival
- bacteria such as strep pneumoniae, nesseria meningitidis and haemophilus influenzae produce a slippery mucoid capsule that prevents phagocytosis by host immune cells
- eliminate O-antigen on lipopolysaccharide to diminish immune recognition and clearance
63
biofilm bacteria are protected from
nutrient deprivation, predators, environmental shifts, antimicrobial agents, and host immune cells
64
some pathogenic bacteria within biofilms exchange
plasmids, nutrients, and quorum sensing molecules which alters their behavior. this makes the biofilm community less sensitive to antibiotics and host defense mechanisms
65
large segments of bacterial chromosomal and plasmid DNA found to encode virulence factors
pathogenicity islands
66
what do pathogenicity islands do?
increase bacterial virulence
absent in nonpathogenic members of same genus or species
genes can be spread from one bacterial cell to another
67
substance that disrupts the normal metabolism of the host cells
toxin
68
pathogens ability to produce toxins
toxigenicity
69
diseases that rely from entry of a specific preformed toxin into host
intoxications
70
intoxications do not require the presence of
the actively growing pathogen, just the toxin
71
soluble, heat-liable proteins
exotoxins
72
often travel from site of infection to other body tissues or target cells where they exert their effects
exotoxins
73
exotoxins are encoded by
genes of plasmids or prophages within bacteria
74
what are among the most lethal substances known?
exotoxins
75
AB toxin
two subunit types
- A subunit - catalyze reaction that cause toxicity
- B subunit - binds to host cell receptor
76
types of exotoxins
AB toxin
specific host site endotoxins
membrane destabilizing exotoxins
superantigens
77
what do superantigens do?
stimulate about 30% of host T cells of the immune system
- Causes T cells to overexpress genes that encode cytokines and release pro-inflammatory molecules
- results in failure of multiple host organs allowing time for the microbe to disseminate
78
Lipopolysaccharide is an
endotoxin
79
why is LPS called a endotoxin?
it is bound to the bacterium and released when the microrganism lyses.
80
what is the toxic component of the LPS?
the lipid portion - lipid A
81
general features of endotoxins
heat stable
toxic
generally similar despite their source
cause general system effects - fever, shock, damage to lining of blood vessels, inflammation, weakness
82
what are toxins produced by fungi?
mycotoxins
83
common contaminates of food crops
mycotoxins
84
initial diagnositcs
samples taken directly from patients are often gram stained before being cultured
85
information obtained from direct smear may help determine
- suitability of the specimen for identification
- the predominant organism is a mixed specimen
- appropriate medium for culture
- appropriate antibacterials for sensitivity testing
86
serologic methods
typically involves testing an unknown antibody against a known antigen bound to a latex particle or similar structure
87
direct methods
microscopy
stained specimen
electron microscopy
immunofluorescence
virus culture
88
indirect methods
antigen detection
antibody detection
PCR
sequencing technologies
89
viruses and parasites are not routinely cultured on
conventional agar
- indirect methods are more suitable
- conventional stains are effective against them
90
microscopy is useful for
some protzoa and parasites
not fit for viruses
91
viruses are not
stained
92
electron microscopy is used for
certain viruses not grown in cell cultures
93
immunoflorescence is the direct exam of
viral particle
94
immune elctron microscopy improve
virus detection by reacting with specific antibodies
95
antigen detections are ___ tests
rapid tests like swabs for influenza virus
96
what happens in antigen detection?
viral antigens are separated on filter paper
can identify specific antibodies
97
companion animal zoonotic disease
- rabies virus
- rabies lyssavirus
- bites from infected animals
98
livestock zoonotic disease/one I am at risk for because of career
- listeriosis
- listeria monocytogenes
- ingestion of contaminated foods or direct contact with reproductive tissues
99
wildlife zoonotic disease
- Staphylococcus
- staphylococcus aereus
- direct contact (skin, wounds, feces), ingestion (contaminated foods), fomites (equipment), inhalation (aerosols, dust)
100
epizoonotic potential
outbreak
101
enzootic potential
always there
102
Which type of immunity is the least common in livestock and companion animal management?
passive artificial
103
Which is not a characteristic of specific (adaptive) immunity?
repair
104
what are the characteristics of specific (adaptive) immunity?
Memory
Diversity
Specificity
105
Which immunoglobulin is associated with mucosal secretions?
IgA
106
which mode of transmission is reduced by using artificial insemination?
direct contact
107
which is associated with endogenous antigen processing
MHC1
108
Which activation method is more effective
T-cell dependent B-Cell activation
109
Which statement about T cells is false?
Once activated they proliferate into mature cells and memory cells
110
T cells
- have a role in activating macrophages, stimulating B Cells, and regulating inflammatory cytokines
- Mature T cells are naïve until activated by antigen presentation
- Originate from stem cells in the bone marrow but mature in thymus
111
It is a dry, breezy day and the cattle are in dirt pens. You are concerned about the breeze going from the sick pen to health animals. What type of transmission are you concerned about?
indirect airborne
112
Least common mode of transmission, diseases transferred by this method are referred to as congenital infections
vertical
113
gram positive cell walls
- composed of mainly peptidoglycan
- teichoic acids - maintain cell envelope, protect from environmental substances, may bind to host cells
SINGLE LAYER
114
gram negative cell walls
- more complex
- outer membrane composed of lipids, lipoproteins, and LPS
- Braun's lipoproteins connect outermembrane to peptidoglycan
2 LAYERS
115
bacterial cell organization
internal structures
cytoplasm
cell envelope (3 layers)
external structures
116
internal structures
- inclusions - granules that are stockpiled nutrients for cells future use
- ribosomes - complex protein synthesis
- nuleoid - chromosome associated proteins
- plasmids - extrachromosomal DNA - contain few genes that are nonessential
117
cell envelope
plasma membrane - encompasses the cytoplasm, selectively permeable, interacts with external environment
cell wall
layers outside of cell wall
118
bacterial cell wall
peptidoglycan - rigid structure
- maintain shape
- protect cell from toxic materials and osmotic lysis
- may contribute to pathogenicity
119
LPS
3 parts
- lipid A - embedded in outer membrane
- core polysaccharide - extend out from cell
- O side chain (O antigen) - extend out from cell
120
what do LPS do?
- neg charge on cells surface
- stabilize outer membrane structure
- attachment to surfaces and biofilm formation
- creates permeability barrier
- protection from host defenses (O antigen)
- can act as an endotoxin (lipid A)
121
components outside of bacterial cell wall
- capsules - structure, protection, composed of polysaccharides, well organized
- slime layers - diffuse, aid in motility
- S layers - protect from environment
122
main function for envelope layer
plasma membrane - encompasses cytoplasm
cell wall - structure
capsule - protection
123
external structures bacterial cell
pili and fimbriae
flagella
124
virus structure
all virons contain a nucleocapsid which is composed of nucleic acid and protein coat
NUCLEIC ACID AND CAPSID
125
capsids
protein coat over the virus mode of protomers
helical, icosahedral, complex
126
viral envelope proteins
- viral attachment to host cell
- ID of virus
- enzymatic activity
- role in nucleic acid replication
127
selective toxicity
ability of drug to kill or inhibit pathogen while damaging host as little as possible
128
how selective toxicity applies to treating bacterial, viral, fungal, and protozoal infections
protozoa and fungi are eukaryotes like animals so their cell structure is more similar to that of an animal meaning creating medications to have a selective toxicity to them is more complex than that of a bacteria or virus
129
bacterial drug resistance
- intrinsic - part of structural/naturally that way/born with it
- acquired - when there is a change in genome of a bacterium that converts it from one that is sensitive to an antibiotic to one that is resistant
130
overcoming drug resistance
- give drug in appropriate concentrations to destroy susceptible microbes and most spontaneous mutants
- give 2 or more drugs at same time
- use drugs only when necessary
- development of new drugs or use bacteriophages to treat bacterial disease (future soln)
131
mechanisms of drug resistance
- modify the target
- drug inactivation
- minimize concentration of antibiotic In the cell
- bypass the biochemical rxn inhibited by the agent or increase production of the target metabolite
132
An example of an enzootic disease
campylobateriosis because it can be contracted at any point from ingestion of raw milk or undercooked meat and direct contact with animals. This is present at low levels at all times in a normal population.
133
An example of an epizootic disease
influenza A which can transfer back and forth between animals and humans and cause unprecedented outbreaks as the virus mutates.
