UNIT 8: HOST MICROORGANISM INTERACTION Flashcards
1
Q
o Growth and multiplication of microorganisms that cause damage to the host
o Bodily invasion of pathogenic microorganisms that reproduce, multiply, and then cause disease through local injury, toxin secretion, or An-Ab reaction to the host
A
Infection
2
Q
caused by microorganisms from the microbiota of the host
A
Autogenous infection
3
Q
result of medical treatment or procedure
A
iatrogenic infection
4
Q
affects immunocompromised host
A
Opportunistic infection
5
Q
hospital-acquired infection
A
nosocomial infection
6
Q
4 common types of nosocomial infection
A
-UTI
-Lung infection (Pneumonia)
-Surgical site infection
-Bloodstream infection
7
Q
disease that occurs occasionally
A
sporadic
8
Q
it is when a disease is constantly present at some rate of occurrence in a particular location
A
endemic
9
Q
a larger than normal number of diseased or infected individuals in a particular location
A
epidemic
10
Q
a larger than normal number of diseased or infected individuals that occurs over a relatively short period
A
outbreak
11
Q
an epidemic that spans the world
A
pandemic
12
Q
a person who carries the etiologic agent but shows no apparent signs or symptoms of infection or disease
A
carrier
13
Q
harbors the microorganism temporarily for a few days or weeks
A
casual / acute / transient carrier
14
Q
remain infected for a relatively long time, throughout its entire life (Typhoid Bacillus)
A
chronic carrier
15
Q
remain infected for a relatively long time, throughout its entire life (Typhoid Bacillus)
A
chronic carrier
16
Q
recovered from infection but continuous to harbor larger numbers of the pathogen
A
convalescent carrier
17
Q
overt clinical case of the disease
A
active carrier
18
Q
what are phases of infectious diseases?
A
Incubation Period
Prodromal Period
Clinical or Illness Period
Decline Period
Convalescence Period or Period of Recovery
19
Q
time between the exposure to a pathogenic organism and the onset of symptoms
A
incubation period
20
Q
a phase where there is appearance of signs and symptoms
A
Prodromal Period
21
Q
a phase where there is peak of characteristic signs and symptoms
A
Clinical or Illness Period
22
Q
phase where signs and symptoms begin to subside as the host’s condition improves
A
Decline Period
23
Q
phase wherein the host is recuperating towards full recovery
A
Convalescence Period or Period of Recovery
24
Q
A microorganism responsible for causing infection or infectious disease
A
Causative / Etiologic Agent
25
Organism capable of producing disease
Pathogen
26
A quantitative measure of the degree of pathogenicity of a particular microorganism
Virulence
27
Microorganism that does not cause disease; may be part of the normal flora
Nonpathogenic
28
An agent capable of causing disease only when the host’s resistance is impaired
Opportunistic pathogen
29
examples of opportunistic pathogen
-PAE
- Stenotrophomonas maltophilia
30
Means by which etiologic agents are brought in contact with the human host
mode of transmission
31
A non-living entity that is contaminated with the etiologic agent and as such is the mode of transmission for that agent
Vehicle / Fomite
32
A living entity (animal, insect, or plant) that transmits the etiologic agent
Vector
33
An animal or plant that harbors or nourishes another organism
Host
34
An organism which is dependent on another organism for food and shelter
Parasite
35
any type of epidemiologic investigation that involves data collection for characterizing circumstances surrounding the incidence or prevalence of a particular disease or infection
Surveillance
36
The state of disease and its associated effects on the host
morbidity
37
Death resulting from disease
mortality
38
Laboratory-based characterization of etiologic agents designed to establish their relatedness to one another during a particular outbreak or epidemic
Strain typing
39
Origin of the etiologic agent or location from which they disseminate
Reservoir
40
The etiologic agent responsible for an epidemic or outbreak originates from a single source or reservoir
Common source
41
association of two organisms living in close proximity
Symbiosis
42
refers to a mutually beneficial relationship between two species
mutualism
43
a relationship wherein the parasite derives benefits from the host without causing injury or harm to the host
commensalism
44
a relationship whereby one organism derives benefits at the expense of another
parasitism
45
ability of the organism to produce disease
pathogenicity
46
large groups of genes that are associated with pathogenicity and are located on the
bacterial chromosome
pathogenicity islands
47
the ability of the organism to enter host tissues , multiply, and spread faster
invasiveness
48
ability of the organism to produce toxins
toxigenity
49
non-poisonous forms of toxins which can be
used for vaccination
toxoid
50
preparation of toxoid
- by aging
- by exposure to heat
- by exposure to 50% alcohol, formaldehyde, and dilute acids
51
general stages of microbial-host interaction
1. physical encounter between host and microorganism
2. microorganism colonization of host surface(s)
3. microorganism entry, invasion, and dissemination
4. outcome
52
microorganisms that are commonly found on or in body sites of healthy persons
normal / indigenous / usual flora
53
microorganisms that colonize an area for months or years
resident microbial flora
54
microorganisms that are present at a site temporarily represent
transient flora
55
presence of flora depends on what factors?
- physiologic factors or temperature
- moisture
- presence of certain nutrients and inhibitory substances
56
roles of microbial flora?
1. provide a first line of defense against microbial pathogens
2. assists in digestion and absorption of nutrients; also synthesis of Vitamin K
3. play a role in toxin degradation
4. contribute to maturation of the immune system
57
ability of a microbe to produce disease in a susceptible individual
pathogenicity
58
are organisms recognized to cause disease in healthy immunocompetent individuals
true pathogens
59
examples of true pathogens?
Yersinia pestis
Bacillus anthracis
60
cause disease if the host is immunocompromised
opportunistic pathogens
61
o relative ability of a microorganism to cause disease or the degree of pathogenicity
o measured by the numbers of microorganisms necessary to cause infection in the host
virulence
62
Microbial Virulence Factors
a. Inhibiting phagocytosis
b. Facilitating adhesion to host cells or tissues
c. Enhancing intracellular survival after phagocytosis
d. Damaging tissue through the production of toxins and extracellular enzymes
63
o Mask the cell surface structures that are recognized by receptors on the surface of the phagocytic cell
o Inhibits the activation of complement by masking structures to which complement proteins bind
capsule
64
o found in the cell wall of Staphylococcus aureus
o Interfering with the binding of the host’s antibodies to the surface of the organism
o Binds to the Fc portion of IgG preventing opsonization and phagocytosis by turning the antibody around on the surface
Protein A
65
heat resistant and acid resistant protein, mediates attachment to host epithelial cell and helps resist phagocytosis
M protein
66
resists digestion during phagocytosis; the bacteria can even multiply inside macrophages
Mycolic acid
67
o produced by Streptococci
o lyse red blood cells and induce toxic effects on WBC
hemolysins
68
o realesed by pathogenic staphylococci
o cause lysosomal discharge into cell cytoplasm
leukocidins
69
- Staphylococcal leukocidin
- Lethal to leukocytes and contributes to the
invasiveness of the organism
Panton-Valentine
70
Cell surface structures that mediate attachment
adhesins
71
enable bacteria to adhere to host cell
surfaces, offering resistance by attachment to target cells and
increasing the organism’s colonizing ability
fimbriae (pili)
72
what are the main adhesins in bacteria?
-fimbriae (pili)
-surface polysaccharides
73
Use lactoferrin as a source of iron
meningococci
74
organisms that produce an IgA protease that
degrades the IgA found at mucosal
surfaces
H. influenzae,
N. gonorrhoeae, and
N. meningitides
75
Circumvent host antibodies by
shifting key cell surface antigens
Borrelia spp.
76
microorganisms able to multiply intracellularly
Chlamydia, Mycobacterium,
Brucella, and Listeria
77
ability of microorganism to penetrate and grow in tissues
invasion
78
ability of disease or organisms to spread to distant sites
dissemination
79
a highly invasive organism that
may not disseminate
Clostridium perfringens
80
poisonous substances produced by organisms that interact with host cells, disrupting normal metabolism and causing harm
Toxins
81
soluble substances that liquefy the hyaluronic acid of the connective tissue matrix, helping to spread bacteria in tissues, promoting the dissemination of infection
Proteases and Hyaluronidases
82
breaks down collagen, which
forms the connective tissue of
muscles and other body organs
and tissues
collagenase
83
hydrolyzes hyaluronic acid, a type
of polysaccharide that holds
together certain cells of the body,
particularly cells of the connective
tissue helping the organism spread
from its initial site of infection
hyaluronidase
84
example of organisms in hyaluronidase
Streptococcus pyogenes (cellulitis)
Clostridium perfringens (gas gangrene)
85
produced by S. aureus and
accelerates the conversion of
fibrinogen to a fibrin clot
coagulase
86
Destroy IgA antibodies found on
secretions
immunoglobulin A protease
87
Destroy neutrophilic leukocytes and macrophages
Leukocidin
88
2 subunits of exotoxin?
- nontoxic (binds the toxin to the host cells)
- toxic
89
T or F
exotoxins are produced by both gram-negative and gram-positive bacteria
T
90
- Encoded by phages, plasmids, or transposons→most toxic
substances
- Good antigens and induce the production of antibodies
called "ANTITOXINS"
toxin gene
91
when exotoxin polypeptides are treated with formaldehyde (or acid or heat), these endotoxin polypeptides can be converted to what?
toxoids (which are used in protective vaccines)
92
examples of toxoids include:
- Diphtheria toxin
- Tetanospamin
- Botulism toxin
- Heat labile enterotoxin by E. coli, Vibrio, and Bacillus
- Verotoxin
- Erythrogenic toxin
- Tree toxins of B. anthracis (ef, pa, lf)
- Toxic shock syndrom toxin 1 (TSST-1)
93
transcribe ef, pa, lf
- edema factor
- protective antigen
- lethal factor
94
3 principal types of exotoxin on the basis of structure and function?
1. A-B toxin
2. Membrane-Disrupting Toxin
3. Supernantigen
95
Consists of two domains or subunits, one responsible for binding to the cell and entry into the cell and the other
possessing the toxic activity
A-B toxin
96
cause lysis of host cells by disrupting their plasma membrane; some form protein channels in the plasma membrane (S. aureus); others disrupt the phospholipid portion of the membrane (C. perfringens)
Membrane-Disrupting toxins
97
Example of Membrane-Disrupting toxins?
- Leukocidins
- Hemolysins
98
antigens that provoke a very intense immune response; non-specifically stimulate the proliferation of immune
cells called T cells, which in turn secrete enormous amounts of cytokines
Superantigens
99
inhibits protein synthesis and
affects the heart, nerve tissue, and liver
diphtheria toxin
100
neurotoxin that blocks nerve
impulse transmission, causing flaccid paralysis, especially in infants → FLOPPY BABY
botulinum toxin
101
produce "EXFOLIATIN" which causes rash and massive skin peeling or exfoliation
Streptococcus pyogenes and Staphylococcus aureus
102
give 3 examples of superantigens?
1. Diphtheria toxin
2. Botulinum toxin
3. Streptococcus pyogenes and Staphylococcus aureus
103
Neurotoxin; prevents the transmission of nerve impulses ➡️ flaccid paralysis
Clostridium botulinum - botulism
104
Neurotoxin, blocks nerve impulses to muscle relaxation pathway ➡️ spastic paralysis
Clostridium tetani - tetanus
105
Cytotoxin, inhibits protein synthesis (esp. in nerve, heart, and kidney cells)
Corynebacterium diphtheriae - Diphtheria
106
Causes skin layers to separate and slough off (scalded skin)
Staphylococcus aureus - scalded skin syndrome
107
Enterotoxin, causes secretion of large amounts of fluids and electrolytes that result in diarrhea
Vibrio cholerae - cholera
108
bacterium associated with traveler’s diarrhea?
- Enterotoxigenic E. coli (ETEC)
- Shigella spp.
109
composed of the LPS portion of the outer membrane on the cell wall of gram-negative bacteria
endotoxins
110
role of endotoxins?
1. stimulate the fever centers of the hypothalamus (1hr after exposure)
2. hypotension (30 mins after exposure) ➡️ shock
3. initiates coagulation ➡️ DIC (Disseminated Intravascular Coagulation)
4. severe neutropenia
5. activate macrophage, complement, and has adjuvant effect on protein antigens
6. stimulates interferon production and causes changes in carbohydrates, lipids, iron, and sensitivity to epinephrine
111
microorganisms that are capable of penetrating normal, healthy skin
Leptospira spp.
Francisella tularensis
Treponema spp.
112
primary mechanical barrier to infection
healthy, intact skin
113
o low-molecular-weight (approximately 20,000 D) enzyme
that hydrolyzes the peptidoglycan layer of bacterial cell walls
o found in serum, tissue fluids, tears, breast milk, saliva, and sweat
lysozyme
114
- found in mucous secretions of the respiratory, genital, and digestive tracts
- serve as opsonins, fix complement and neutralize the infecting organism
secretory IgA
115
- low-molecular-weight cationic proteins in serum
- lethal against gram-positive bacteria and are released from platelets during coagula.on
ß-lysins
116
inhibits proliferation of viruses
interferon
117
compete with pathogens for nutrients and space
indigenous microbial flora
118
substances that inhibit the growth of closely related bacteria
bacteriocins
119
Particle is taken into the cytoplasm and enclosed within a vacuole called
phagosome
120
Phagosome fuses with lysosomes = ?
phagolysosome
121
Lysosomes release their contents into the phagosome → ?
degranulation
122
myeloperoxidase, proteases, cathepsin, lactoferrin,
lysozyme, and elastase ➡️ necessary for the killing and digestion of the engulfed particles
lysosomes
123
CARDINAL SIGNS OF INFLAMMATION:
redness
swelling
heat
pain
loss of function
124
CHEMICAL MEDIATORS OF INFLAMMATION
histamine
kinins
leukotrienes
prostaglandins
acute phase reactants
cytokines
125
mechanism whereby the body is able to protect itself from invasion by disease-causing organisms
immunity
126
consists of numerous cells and protein molecules that are responsible for recognizing and removing these foreign substances
immune system
127
constituents of the adaptive or specific immune response
lymphocytes and antibodies
128
primary effector cell in
cell-mediated immunity
t lymphocytes
129
microorganism mot is thru dog-bite and cat-bite infec.ons
Pasteurella multocida
130
Inhibits transpeptidation and cell wall synthesis
beta lactam
131
Inhibits translocation and elongation of peptidoglycan layer
vancomycin
132
Inhibits synthesis of peptidoglycan precursors
bacitracin
133
Acts only on growing cells and can either be a bactericidal or bacteriostatic
isoniazid
