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Pathogenesis Flashcards

1
Q

Pathogen

A

Organism that produces disease

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2
Q

Opportunistic pathogen

A

Infects host with weakened immune system (immunocompromised)

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3
Q

Carrier

A

Infected individual with no observable symptoms

Potential source of infection

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4
Q

Zoonoses

A

Diseases transmitted to humans from animals

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5
Q

Vectors

A

Organisms (usually insects) that transmit disease to humans (examples: mosquitoes, ticks, fleas)

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6
Q

Pathogenicity

A

Ability to produce disease

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7
Q

Virulence

A

Degree of pathogenicity

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8
Q

Latency

A

Pathogen stops reproducing and becomes dormant

Can become active again

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9
Q

How do we study pathogenicity? (3 ways)

A

Model systems
Human studies
Epidemiology

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10
Q

2 examples of model systems used to study pathogenicity

A

Animal models

Cell culture

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11
Q

2 examples of human study methods used to study pathogenicity

A

Clinical trials

Case studies

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12
Q

3 methods of studying epidemiology in relevance to pathogenicity

A

Examine incidence, distribution, and control of disease

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13
Q

2 methods of measuring virulence

A

Lethal dose 50 (LD50)

Infectious dose 50 (ID50)

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14
Q

Lethal dose 50 (LD50) definition

A

Number of pathogens needed to kill 50% of hosts

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15
Q

Infectious dose 50 (ID50) definition

A

Number of pathogens required to cause clinical disease in 50% of inoculated hosts

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16
Q

6 mechanisms of pathogenicity

A 
Attachment
Invasion
Colonization 
Immune evasion
Virulence factors/determinants
Pathogenicity islands
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17
Q

Virulence factors/determinants

A

Genetic, biochemical, or structural features that contribute to virulence

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18
Q

Pathogenicity islands

A

Large DNA regions that encode virulence factors

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19
Q

Do pathogens usually use one virulence factor or an arsenal of them?

A

Arsenal of virulence factors

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20
Q

Viral attachment: ____ and ____ ____ proteins mediate attachment

A

Capsid

Envelope spike

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21
Q

Example of viral attachment in HIV

A

gp120 binds CD4 and CCR5

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22
Q

Example of viral attachment in influenza

A

Hemagglutinin binds sialic acid in respiratory tract

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23
Q

Viral spread: viruses can spread via ____, ____, or ____ systems

A

Blood
Neuronal
Lymphatic

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24
Q

Tropism

A

Cell, tissue, or organ specificity of a pathogen

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25
How is tropism determined?
Host cell receptors
26
How can viruses evade innate immune responses? (2)
Block or breakdown complement | Block interferon production
27
How can viruses evade adaptive immune responses?
Block antigen processing and MHC export | Evade antibodies
28
What mechanism do viruses use to evade antibodies? How does it work?
Antigenic variation | Amino acid changes in virion spikes
29
In what type of viruses is antigenic variation commonly used?
RNA viruses
30
2 methods of bacterial attachment
Pili | Capsules
31
Examples of capsulated bacteria (4)
Streptococcus pneumoniae Haemophilus influenzae Neisseria meningitidis Pseudomonas aeruginosa (mucoid strains only)
32
Pseudomonas aeruginosa is what type of pathogen in what 2 groups of people?
Opportunisitic pathogen | Burn and cystic fibrosis patients
33
Coagulase: what is it and what does it do
Virulence determinant for invasion and spread Clots fibrinogen in plasma Clot protects pathogen
34
Streptokinase: what is it and what does it do
Virulence determinant for invasion and spread | Activates plasmin, which digests fibrin clots, enabling pathogen to move from clotted area (coagulase)
35
IgA protease: what is it and what does it do
Virulence determinant for invasion and spread | Destroys antibodies
36
Hemolysin: what is it and what does it do
Virulence determinant for invasion and spread | Digests red blood cells, releasing iron
37
Siderophore: what is it and what does it do
Virulence determinant for invasion and spread | When released, binds free iron for bacterial uptake
38
DNase: what is it and what does it do
Virulence determinant for invasion and spread | Lowers viscosity of secretions, so bacteria can spread
39
Bacteremia
Presence of bacteria in bloodstream
40
Neutrophil extracellular traps (NETs)
DNA and antimicrobial proteins and enzymes spit out of neutrophil to trap pathogens
41
Intracellular bacterial pathogen examples (5)
``` Chlamydia Legionella Mycobacterium tuberculosis Salmonella Listeria monocytogenes ```
42
Listeria monocytogenes: Gram positive or negative, what type of pathogen
Gram positive | Food-borne pathogen
43
What types of food can carry Listeria monocytogenes?
Produce Raw (unpasteurized) milk Cheese Deli meat
44
What type of extremophile is Listeria monocytogenes?
Psychrophile
45
What can Listeria monocytogenes cross?
Placenta
46
How does Listeria monocytogenes move inside host cells?
Polymerization of host actin
47
Streptococcus pneumoniae causes what type of infection by forming what?
``` Otitis media (infection of middle ear) Forms biofilm ```
48
Pseudomonas causes infection in what organ of what individuals by forming what?
Lung of cystic fibrosis patients | Forms biofilm
49
Staphylococcus and Enterococcus cause what infection on what body part by forming what?
Endocarditis | Form biofilm on heart valves
50
Streptococcus mutans (along with other bacteria) causes what condition by forming what?
Dental plaque | Forms biofilm
51
Biofilms enable bacteria to evade innate, adaptive, or both immune systems?
Both
52
Biofilms protect bacteria from what part of the adaptive immune system and what part of the innate immune system?
Adaptive: antibodies (can't bind) Innate: phagocytes (can't engulf)
53
How do biofilms protect from antibiotics?
Matrix and slow growth of microbes in biofilms inhibits antibiotics
54
Toxins
Substances that damage host
55
2 types of toxins and how they are differentiated
Exotoxin is made and released by bacterial cell | Endotoxin is part of bacterial cell
56
4 types of exotoxin
Membrane disrupting Superantigens AB Specific host site
57
How do membrane-disrupting exotoxins function?
Form pores
58
2 examples of pore-forming exotoxins
Leukocidins | Hemolysins
59
Leukocidins form holes in what type of cells?
Leukocytes
60
Hemolysins form holes in what type of cells for what purpose?
Red blood cells | Makes iron available to pathogens
61
How do pores in host cell plasma membrane destroy host cells?
Hole in host cell plasma membrane causes swelling due to water rushing into cell and then causes cell to lyse
62
Superantigens bind both ____ and _____. This causes what to happen?
MHC and TCR | Locks them in place
63
Superantigens cause ____ cells to overexpress, releasing ____.
T cells | Cytokines
64
Overexpression of T cells by superantigen causes failure of multiple ____.
Organs
65
Toxic shock syndrome is caused by what type of exotoxins produced by what genus and species of bacteria?
Superantigen | Staphylococcus aureus
66
AB exotoxins have what 2 subunits for what purposes?
A: toxic effect B: binds target cell receptor
67
Many AB exotoxins are ___-_____ _____. What does that mean?
ADP-ribosyl transferases | Remove ADP-ribose group from NAD and attach it to host cell protein, which is then inactivated or functions irregularly
68
What bacteria causes diphtheria?
Corynebacterium diphtheriae
69
Diphtheria AB exotoxin steps (5)
1. AB toxin binds to host growth factor receptor 2. AB toxin enters by endocytosis 3. Vesicle is lowered in pH, causing separation of A and B toxins 4. A portion takes ADP-ribosyl group from NAD and puts it onto elongation factor II (EF-2) 5. ADP-ribosyl-EF-2 can no longer function in translation, so cell dies
70
Cholera produces what type of exotoxin and is produced by what genus and species?
AB exotoxin | Vibrio cholerae
71
What kind of toxin is cholera AB toxin?
Enterotoxin (attacks intestine)
72
Botulinum toxin is an ____ _____ produced by what genus and species?
AB neurotoxin | Clostridium botulinum
73
Cholera AB toxin steps (5)
1. B subunit of AB toxin binds to ganglioside receptor 2. A subunit ADP-ribosylates G protein, stimulating it 3. G protein activates adenylate cyclase, which produces cyclic AMP 4. Cyclic AMP activates CFTR chloride channel (cyctic fibrosis transmembrane conductance regulator) 5. Chloride is pumped out along with sodium and water, causing profuse watery diarrhea
74
Botulinum toxin blocks release of ____ at ____ ____. What does this mean for the host?
Acetylcholine Neuromuscular junction Muscules can't contract, causing flaccid paralysis
75
Botulinum toxin is used to make ____. It can be used to treat ____, _____, and _____ ____.
Botox | Migraines, spasms, excessive sweating
76
Antibodies can also be called what? What do they do to exotoxins?
Antitoxin | Neutralize toxicity
77
Are exotoxins stable or unstable? If they lose toxicity, they remain _____.
Unstable | Remain antigenic
78
Toxoid: definition, basis of what kind of vaccines, example vaccine that is this type
Inactivated toxin that can still elicit an immune response Toxoid vaccine DTaP (diphtheria, tetanus, pertussis)
79
Example endotoxin
LPS (lipid A portion specifically) of Gram negative bacteria
80
How does LPS function as an endotoxin?
LPS binds TLR4, activating NFkappaB to transcribe genes for cytokines In uncontrolled amounts, cytokines result in fever, inflammation, and blood vessel leakage (causes hypotension)
81
The actions of endotoxin LPS can lead to what?
Septic shock
82
Sign of septic shock
Petechia (red spots coming from leaky blood vessels)
83
Septic shock is a common cause of death where?
Intensive care units
84
Sepsis: definition and symptoms
Systemic response to microbial infection Elevated temperature, heart, and respiratory rate Elevated leukocyte count
85
Shock
Sepsis with hypotension
86
Septicemia
Systemic disease in which microbes multiply in blood
87
Type III secretion: infection by ____
Injection
88
Type III secretion is used by many Gram ____ bacterial ___ and ____ pathogens
Negative | Plant and human pathogens
89
Type III secretion is carried out by what bacterial structure?
Injectisome
90
3 parts of injectisome
Basal body Needle Pore
91
Injectisome injects what?
Effector proteins
92
2 targets for type III effectors
Host cell cytoskeleton (actin) | Host cell signaling (NFkappaB)
93
How do type III effectors target host cell cytoskeleton (actin)?
``` Promote invasion Block phagocytosis (macrophages need actin to phagocytose) ```
94
How do type III effectors target host cell signaling (NFkappaB)?
Block cytokine production Promote intracellular survival Induce apoptosis

Microbiology (24 decks)

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