Microbial Pathogenesis Flashcards

1
Q

pathogenicity

A
  • organism’s ability to cause disease
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2
Q

pathogenesis

A
  • process resulting in disease
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3
Q

pathogen

A
  • organism that can cause disease
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4
Q

virulence

A
  • degree of damage or disease resulting from infection
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5
Q

infectivity

A
  • likelihood of causing infection and/or disease with exposure to a particular dose
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6
Q

rhinovirus

A
  • ss+RNA
  • naked virion
  • causes common cold
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7
Q

rhinovirus infectivity/virulence

A
  • high infectivity

- low virulence

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8
Q

influenza virus

A
  • ss-RNA
  • segmented
  • enveloped
  • causes flu
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9
Q

influenza virus infectivity/virulence

A
  • moderate infectivity
  • greater virulence
  • host dependent
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10
Q

Ebola

A
  • ss-RNA
  • enveloped
  • causes hemorrhagic fever
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11
Q

Ebola infectivity/virulence

A
  • high infectivity

- high virulence

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12
Q

acquisition/transmission of microbial agents

A
  • endogenous

- exogenous

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13
Q

endogenous transmission of microbial agents

A
  • organism escapes from location where it is part of the normal microbiome
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14
Q

exogenous transmission of microbial agents

A
  • person to person
  • animal to person
  • insect to person
  • environmental
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15
Q

person to person

A
  • communicable disease
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16
Q

vertical person to person

A
  • mother to child
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17
Q

animal to person

A
  • zoonoses
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18
Q

insect to person

A
  • vector borne
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19
Q

environmental transmission

A
  • nature
  • nosocomial
  • fomite
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20
Q

routes of transmission

A
  • entry via epithelial surfaces

- deeper tissue penetration

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21
Q

entry via epithelial surfaces

A
  • inhalation
  • ingestion
  • sexual contact
  • exposure during vaginal birth
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22
Q

deeper tissue penetration

A
  • spread from epithelia
  • insect bites
  • cuts and wounds
  • organs transplants and blood transfusions
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23
Q

encounter

A
  • infectious agent meets host
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24
Q

entry

A
  • agent enters host
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25
spread
- agent spreads from site of entry
26
multiplication
- agent multiplies within host
27
damage
- agent - host response - both - cause tissue damage
28
outcome
- agent or host wins | - learn to coexist
29
microbial virulence factors
- not required for growth outside infected host
30
categories of virulence factors
- structures involved in attachment, adherence and invasion - toxins involved in cell or tissue damage - processes involved in immune avoidance
31
pili characteristics
- filamentous structures extending from bacterial surface - shorter, thinner, more numerous - polar or peritrichous
32
pili function
- initial adherence to host cells or extracellular matrix
33
specificity of pili adherence
- nonspecific or highly specific
34
polymers of pili
- pilins | - may be homo or heteropolymers
35
Type IV pili
- extend, bind, and retract - promote surface motility, micro colony and biofilm formation - adherence to host cells and immune evasion
36
type IV pili expressed by
- N. meningitis and N. gonorrhea - P. aeroginosa - H. influenzae - V. cholera
37
flagella composed of
- flagellin - H antigen
38
flagella characteristics
- longer, thicker, fewer | - usually polar
39
function of flagella
- movement through environment (locomotion)
40
specialized bacterial secretion systems
- gram negative bacteria use type III, IV, and V systems to inject substances into other cells
41
translocated substrates that are virulence factors
- toxins | - receptors
42
viral attachment mediated by
- proteins on surface of virion
43
capsid proteins on naked viruses
- engage receptor on host cells
44
how does the virus enter the host cell with capsid proteins on naked viruses?
- endocytosis
45
glycoprotein spikes on enveloped viruses
- engage receptor on host cell
46
how virus enters host cells with glycoprotein spikes on enveloped viruses
- enters via membrane fusion or endocytosis
47
naked, ds DNA virus example
- adenovirus
48
ssRNA, enveloped virus example
- HIV
49
O antigens on LPS define
- serotypes
50
Lipid A
- toxic moiety of gram negatives - potent stimulation of innate immune response - important cause of septic shock
51
exotoxins secreted by
- gram positives and gram negatives
52
toxin classification based on
- structure/function | - site of action
53
structure/function toxins
- A + B toxin - pore-forming toxin - superantigen toxin
54
site of action toxins
- enterotoxins - neurotoxins - tissue invasive toxins
55
A+B toxins
- A active | - B binding
56
cholera A toxin
- A + 5B - activates adenylate cyclase, increases cAMP - promotes secretion of electrolytes and fluid by intestinal epithelial cells - leads to diarrhea
57
anthrax toxin
- 2A+B
58
A toxin anthrax
- subunits of edema factor and lethal factor
59
edema factor
- activates adenylate cyclase
60
lethal factor
- cleaves cellular kinases | - leads to altered signaling and cell death
61
A+B toxin mediated disease
- Diptheria - Tetanus - Pertussis - covered by TDaP vaccine
62
diphtheria A subunit
- inhibits protein synthesis
63
tetanus A subunit
- inhibits neurotransmitter release from inhibitory neurons in CNS - results in paralysis
64
pertussis A subunit
- activates adenylate cyclase - increases cAMP in neutrophils and macrophages - decreases phagocytosis
65
pore forming toxin example
- Staph aureus
66
superantigen examples
- staphylococcal and streptococcal toxic shock toxins
67
superantigen
- nonspecific | - stimulates massive polyclonal expansion of many T cells resulting in cytokine storm
68
bacterial structures that avoid immune system
- bacterial and fungal polysaccharide capsules - antigens that induce blocking antibodies - molecules that inactivate antibodies - molecules that mimic host structures and are not recognized as foreign
69
polysaccharide capsules
- avoid phagocytosis - avoid immune recognition by complement and antibody - common feature of pathogens that can disseminate via bloodstream to CNS - adherence
70
processes to avoid immune system
- antigenic variation - avoiding immune surveillance - suppressing immune surveillance
71
N. meningitis
- rmp protein - IgA protease - serogroup B polysaccharide capsule
72
rmp protein
- highly immunogenic | - antibodies don't protect and block binding to other targets
73
igA proteases
- cleave human IgA antibodies
74
serogroup B polysaccharide capsule
- mimics human antigens | - poorly immunogenic
75
antigenic variation
- during infections, pathogens express different versions of key antigens - antibodies made against one version do not recognize later version
76
examples of antigenic variation
- Trypanosoma brucei cause of sleeping sickness - N. gonorrhea and N. meningitides - RNA viruses like HIV, HCV, and flu virus
77
TB avoid immune surveillance
- induces formation of granulomas
78
herpes virus avoid immune surveillance
- travel from periphery to dorsal root ganglia and are latent in sensory neurons
79
T. pallidum avoid immune surveillance
- express few surface proteins | - cause of syphilis
80
TB suppress immune response
- prevents fusion of phagosomes and lysosomes in macrophages