Microbial Pathogenesis Flashcards
1
Q
pathogenicity
A
- organism’s ability to cause disease
2
Q
pathogenesis
A
- process resulting in disease
3
Q
pathogen
A
- organism that can cause disease
4
Q
virulence
A
- degree of damage or disease resulting from infection
5
Q
infectivity
A
- likelihood of causing infection and/or disease with exposure to a particular dose
6
Q
rhinovirus
A
- ss+RNA
- naked virion
- causes common cold
7
Q
rhinovirus infectivity/virulence
A
- high infectivity
- low virulence
8
Q
influenza virus
A
- ss-RNA
- segmented
- enveloped
- causes flu
9
Q
influenza virus infectivity/virulence
A
- moderate infectivity
- greater virulence
- host dependent
10
Q
Ebola
A
- ss-RNA
- enveloped
- causes hemorrhagic fever
11
Q
Ebola infectivity/virulence
A
- high infectivity
- high virulence
12
Q
acquisition/transmission of microbial agents
A
- endogenous
- exogenous
13
Q
endogenous transmission of microbial agents
A
- organism escapes from location where it is part of the normal microbiome
14
Q
exogenous transmission of microbial agents
A
- person to person
- animal to person
- insect to person
- environmental
15
Q
person to person
A
- communicable disease
16
Q
vertical person to person
A
- mother to child
17
Q
animal to person
A
- zoonoses
18
Q
insect to person
A
- vector borne
19
Q
environmental transmission
A
- nature
- nosocomial
- fomite
20
Q
routes of transmission
A
- entry via epithelial surfaces
- deeper tissue penetration
21
Q
entry via epithelial surfaces
A
- inhalation
- ingestion
- sexual contact
- exposure during vaginal birth
22
Q
deeper tissue penetration
A
- spread from epithelia
- insect bites
- cuts and wounds
- organs transplants and blood transfusions
23
Q
encounter
A
- infectious agent meets host
24
Q
entry
A
- agent enters host
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