Pathogenesis Flashcards
1
Q
it is the mechanism of origination and development of signs and symptoms of disease
A
pathogenesis
2
Q
it is the ability of an infectious agent to cause disease
A
pathogenecity
3
Q
a microorganism capable of causing disease especially in immunocompetent people
A
pathogen
4
Q
what are the three types of pathogen?
A
- obligate pathogen
- typical pathogen
- opportunistic pathogen
5
Q
a type of pathogen that causes disease rarely in immunocompetents but cause serious disease in immunocompromised patents, although they are part of the normal body flora
A
opportunistic pathogens
6
Q
an organism’s capacity to cause disease
A
virulence
7
Q
the process by which bacteria stick to the surfaces of host cells
A
adherence
8
Q
what is the major initial step of bacteria, once entered the body, in the infection process?
A
adherence
9
Q
a person or animal with asymptomatic infection that can be transmitted to another susceptible person or animal
A
carrier
10
Q
it is the multiplication of an infectious agent within the body
A
infection
11
Q
multiplication of normal microbiota in the body, such as those seen in GIT, is it an infection or not?
A
not
12
Q
it is the process whereby bacteria, animal parasites, fungi, and viruses enter host cells or tissues and spread in the body
A
invasion
13
Q
microbial flora harbored by normal, healthy individuals are called?
A
microbiota
14
Q
a microorganism that does not cause disease; can be part of the normal microbiota
A
nonpathogen
15
Q
protein toxins that activate the immune system by binding to major histocompatibility complex (MHC) molecules and T-cell receptors (TCR) and stimulate large numbers of T cells to produce massive quantities of cytokines
A
superantigen
16
Q
the ability of a microorganism to produce a toxin that contributes to the development of a disease is called
A
toxigenicity
17
Q
virulence involves 4 process. what are those?
A
adherence, persistence, invasion, and toxigenicity
18
Q
microorganism causing syphilis
A
Treponema pallidum
19
Q
microorganism causing leprosy
A
Mycobacterium leprae
20
Q
microorganism causing gonorrhea
A
Neisseria gonorrhoeae
21
Q
microorganism causing tuberculosis
A
Mycobacterium tuberculosis
22
Q
Although E. coli is part of the human normal microbiota, it still causes disease such as
A
urinary tract infection, and traveler’s diarrhea
23
Q
example of opportunistic pathogens are
A
Pseudomonas spp., Stenotrophomonas maltophilia, and many yeasts and molds
24
Q
how do Salmonella and Campylobacter spp. infect humans?
A
they first infect in animals and are transmitted in food products to humans
25
give examples of microorganisms that caused inadvertent infection
Y. pestis (plague), and Bacillus anthracis (anthrax)
26
How are Clostridium spp. transmitted to humans?
they are ubiquitous in environment and are transmitted to humans by ingestion (eg. C. perfringens [gastroentiritis], and botulinum [botulism], or when wounds are contaminated by soil (e.g. C. perfringens [gas gangrene]), and C. tetanii [tetanus].
27
microorganism that cause voluminous diarrhea
Vibrio chlorae
28
what foods/drinks may be contaminated by V. chlorae for it to transmit disease to humans?
salt and fresh water, drinking water, or seafood such as oysters, and crabs -- ingestion of such may produce infection of disease
29
what provides the primary defense of the humans against bacterial infection?
skin and mucous membranes
30
extrachromosomal pieces of DNA and are capable of replicating
plasmids
31
highly mobile segments of DNA that can move from one part of the DNA to another
transposons
32
transposons may result in?
it may result in the recombination between extrachromosomal DNA and the chromosome (illegitimate or homologous recombination). thus, if this occurs, the genes coding for virulence may be chromosomal
33
large group of genes that are associated with pathogenicity and are located on the bacterial chromosome are called
Pathogenicity Islands (PAIs)
34
usual size of PAIs
10-200 kb
35
major properties of PAIs, true of or false: one or more virulence genes
true
36
major properties of PAIs, true of or false: absent in the genome of pathogenic members, present in genome of nonpathogenic members
false. it is present in pathogenic, and absent in nonpathogenic members.
37
major properties of PAIs, true of or false: have different guanine + cytosine content that other bacterial genome
true
38
major properties of PAIs, true of or false: not associated with tRNA
false. they are commonly associated with them
39
major properties of PAIs, true of or false: found with parts of genome associated with mobile genetic elements
true
40
major properties of PAIs, true of or false: they have genetic stability
false. they have genetic instability
41
major properties of PAIs, true of or false: they often represent mosaic structures with components acquired at different timea
true
42
properties of PAIs suggest that it originates from?
gene transfer from foreign species
43
what signals often controls the expression of virulence genes?
environmental signals
44
examples of environmental signals that is involved in the control of expression of virulence genes
temperature, iron availability, osmolality, growth phase, pH, specified ions (Ca2+), and nutrient factors
45
what would happen if the bacteria do not adhere upon entering the body?
it would be swept away by mucus and other fluids that bathe the tissue surface
46
adherence, a primary process in infection is followed by?
development of microcolonies and subsequent steps in the pathogenesis of infection
47
true or false: the more hydrophobic the bacterial cell surface, the greater adherence to the host cell
true
48
a surface molecule, thick rodlike appendages is called
pili
49
a surface molecule; shorter "hairlike" structures that extend from the bacterial cell surface and help mediate adherence of the bacteria to host cell surface
fimbriae
50
what type of surface molecule does some E. coli strains have?
type 1 pili
51
adherence in vitro can be blocked by addition of?
adherence can be blocked in vitro by addition of D-mannose to the medium
52
what type of surface molecule does E. coli, that causes UTI, have?
it does not have D-mannose-mediated adherence, but rather have P-pili that attaches to portions of P blood group antigen
53
what type of surface molecule does Streptococcus pyogenes have?
fimbriae
54
what are found on the fimbriae?
lipoteichoic acid, protein F, and M protein
55
what causes the adherence of streptococci to buccal epithelial cells?
lipoteichoic acid and protein F
56
adherence of streptococci to buccal epithelial cells is mediated by ?
fibronectin, acting as the host cell receptor molecule
57
what is the function of M protein in the adherence of streptococci to buccal epithelial cells?
it acts as an antiphagocytic molecule and is a major virulence factor
58
it is the term commonly used to describe entry of bacteria into host cells
invasion
59
are virulence properties such as toxin production dependent in the ability of bacteria to invade cells and tissues?
no. they are independent.
60
these undifferentiated unpolarized cells were derived from a cervical carcinoma
HeLa cells
61
what does HeLa stand for?
Henrietta Lacks
62
what property of HeLa Cells resulted in the adherence of Shigella spp. to in vitro host cells?
the adherence causes actin polymerization in nearby portion of HeLa cells, which induces formation of pseudopods by HeLa cells and engulfment of bacteria
63
adherence of shigella spp are mediated by?
they are mediated at least in part by products of genes located on large plasmid common to shigellae.
64
shigella and yersiniae spp in vivo are thought to adhere what cells?
M cells of Peyer's patches rather than mucosal cells
65
how is L. monocytogenes transfered to human?
it is from the environment and ingested in food
66
process of pathogenesis of L. monocytogenes
the bacteria enters the body and adhere and invade the intestinal lining, reach the bloodstream, and disseminate.
67
engulfment process of listeriae spp. requires what for bacteria to propel? same with shigellae
actin polymerization
68
the process of forming long thin pseudopod that coils around the bacteria, forming a vesicle is called
coiling phagocytosis
69
where do legionalle spp multiplies after adhesion?
within the vesicle
70
n. gonorrhea uses two adhesins. what is the primary and secondary adhesins?
primary adhesins - pili
secondary adhesins - opacity associated proteins
71
toxins produced by bacteria are generally classified into two groups. what are those?
endotoxin and exotoxins
72
endotoxins are present in what type of bacteria, and what part specifically?
present in the outer membrane of Gram-negative rods
73
example of toxins secreted are
enterotoxins and exotoxins
74
enterotoxins and exotoxins are often classified by
by mechanisms of action and impact on host cells
75
exotoxins are produced by what bacteria
both gram-positive and gram-negative bacteria
76
vaccines developed for some of exotoxin-mediated disease are called
toxoids
77
toxoids are made up from?
these are modified exotoxins so that they are no longer toxic
78
there are two subunits that many exotoxin consist: A and B subunit. it is also referred as?
binary toxins or type III toxins
79
what is the function of B subunit in exotoxins?
it mediates adherence of the toxin complex to a host cell and aids in the entrance of of the toxin into the host cell
80
what is the function of A subunit in exotoxins?
it provides toxic activity
81
what toxin is produced by strains of c. dipththeriae, and what disease does it cause?
diphtheria toxin, and causes dipththeria
82
vegetative forms of C. tetani produces what toxin?
tetanospasmin
83
the toxin, tetanospasmin, degrades a protein required for docking of neurotransmitter vesicles on the presynaptic membrane. the protein is called?
synaptobrevin
84
how are spores of C. perfringens invading humans?
introduced into wounds by contamination of soil and feces
85
toxins produced by clostridium spp are necrotizing and hemolytic and produces the spread of?
gas gangrene
86
what is the alpha toxin of C. perfringens?
lecithinase
87
how do lecithinase damages cell membranes?
by splitting lecithin to phosphorylchorine and diglycerine
88
what is the toxin the damages cell membranes by splitting lecithin to phosphorylchlorine and diglycerine
the alpha toxine of c. perfringens called lecithinase
89
what toxin does S. aureus elaborate and what disease does it cause?
toxic shock syndrome toxin-1, causing toxic shock syndrome
90
strains of group A B-hemolytic streptococci produces
pyrogenic exotoxin A and C
91
exotoxins associated with diarrheal disease are frequently called
enterotoxin
92
what toxin type family do enterotoxin belong to
type III toxin family
93
toxin of V. cholerae has two subunits; one of which is subunit A that is further split into two peptides - A1 and A2. these two are linked via what bond?
disulfide bond
94
the deleterious effect of cholera are due to
fluid-loss and acid-base imbalace
95
treatment for cholera is through
electrolyte and fluid replacement
96
how many distinct types of staphylococcal enterotoxin are there?
at least 7
97
what is the most common form of food poisoning?
staphylococcal food poisoning
98
what are the three main domains of lipopolysaccharides of gram-negative bacteria?
lipid A, oligosaccharide core, and O antigen polysaccharide
99
what domain of LPS is recognized by the immune system and is responsible for cytoline stimulation?
lipid A
100
what proinflammatory cytokine produces fever after injection of LPS?
IL-1
101
a frequent complication of gram-negative bacteremia, and can also occur in other infections is known as
disseminated intravascular coagulation
102
what is the first step of intrinsic clotting system?
LPS activating factor XII -- the Hageman factor
103
LPS causes platelets to adhere to vascular endothelium and occlusion of small blood vessels which will cause
ischemic or hemorrhagic necrosis in various organs
104
endotoxin levels can assayed by what test?
limulus test: a lysate of amebocytes from the horseshoe crab (limulus) gels of coagulates in the presence of 0.0001 mg/mL of endotoxin
105
why is limulus test rarely done?
because it is difficult to perform accurately
106
the peptidoglycan of gram-positive bacteria is made up of
cross-linked macromolecules that surround the bacterial cells
107
best-characterized tissue degrading enzymes are from what bacterias
C. perfringens, anaerobic bacteria, S. aureus, and group A streptococci
108
a proteolytic enzyme produced by C. perfringens aside from lecithinase?
collagenase
109
what is the function of collagenase?
degrades collagen - the major protein of fibrous connective tissue - and promote spread of infections in tissue
110
tissue degrading enzyme produced by S. aureus that works in conjunction with blood factors to coagulate plasma
coagulase
111
a tissue degrading enzyme that hydrolyze hyaluronic acid
hyaluronidases
112
a substance that activates a proteolytic enzyme of plasma
streptokinase or fibrinolysin
113
streptokinase has been used in treatment of ?
acute myocardial infarction to dissolve fibrin clots
114
a cytolysins that dissolve red blood cells
hemolysins
115
a cytolysins that kill tissue cells or leukocytes
leukocidins
116
what is the secretory antibody on mucosal surfaces
immunoglobulin A (IgA)
117
between the two primary forms of IgA, which is an important virulence of several pathogens?
IgA1 proteases
118
some pathogens evade phagocytosis or leukocyte microbicidal mechanisms by?
by absorbing normal host components to their surface
119
these antigens are used as part of a serologic classification system for bacteria
antigenic heterogenesity
120
what bacteria causes relapsing fever
Borrelia recurrentis
121
gram negative bacteria: thick or thin peptidoglycan?
thin
122
gram positive bacteria: thin or thick peptidoglycan?
very thick
123
what is the general secretion pathway of both gram negative and gram positive bacteria?
sec
124
gram negative have 6 additional secretory systems; determine dependent and independent types
dependent: type 2 and 5
independent: type 1, 3, 4, 6
125
what type of secretory system is activated upon contact with a eukaryotic host cell
type 3 independent ss
126
a needlelike structure used in the direct transport of proteins from inside of bacterium to inside of host cell
injectosome
127
what bacteria have type 33 ss?
pseudomonas aeruginosa
128
a type of secretion pathway that consists of protein complex forming a "tunnel" that is able to directly transport proteins or dna
type 4 secretion pathway
129
an essential nutrient for growth and metabolism of nearly all microorganism and is essential cofactor of numerous metabolic and enzymatic processes
iron
130
an aggregate of interactive bacteria attached to a solid surface or to each other and encased in an exopolysaccharide matrix
biofilm
131
redefined concept: removal of the microbe from the host by physical factors, an immune response, therapy, etc
elimination
132
redefined concept: extremes of infection if the microbe causes sufficient damage to host
death
133
redefined concept: it is defined as the interruption of normal tissue structure and/or function at cell, tissue, or organ level
damage
134
redefined concept: microbe persist within host and causes no damage over time
commensal
135
redefined concept: commensals that benefit from infecting host and provide a benefit to host are called
symbionts
136
when was the virulence concept redefined, and who did it
1999, casadevall and pirofski
