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Pathogenesis Flashcards

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Biology 101 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
Q

How is tropism determined?

A

Host cell receptors

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26
Q

How can viruses evade innate immune responses? (2)

A

Block or breakdown complement

Block interferon production

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27
Q

How can viruses evade adaptive immune responses?

A

Block antigen processing and MHC export

Evade antibodies

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28
Q

What mechanism do viruses use to evade antibodies? How does it work?

A

Antigenic variation

Amino acid changes in virion spikes

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29
Q

In what type of viruses is antigenic variation commonly used?

A

RNA viruses

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30
Q

2 methods of bacterial attachment

A

Pili

Capsules

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31
Q

Examples of capsulated bacteria (4)

A

Streptococcus pneumoniae
Haemophilus influenzae
Neisseria meningitidis
Pseudomonas aeruginosa (mucoid strains only)

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32
Q

Pseudomonas aeruginosa is what type of pathogen in what 2 groups of people?

A

Opportunisitic pathogen

Burn and cystic fibrosis patients

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33
Q

Coagulase: what is it and what does it do

A

Virulence determinant for invasion and spread
Clots fibrinogen in plasma
Clot protects pathogen

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34
Q

Streptokinase: what is it and what does it do

A

Virulence determinant for invasion and spread

Activates plasmin, which digests fibrin clots, enabling pathogen to move from clotted area (coagulase)

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35
Q

IgA protease: what is it and what does it do

A

Virulence determinant for invasion and spread

Destroys antibodies

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36
Q

Hemolysin: what is it and what does it do

A

Virulence determinant for invasion and spread

Digests red blood cells, releasing iron

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37
Q

Siderophore: what is it and what does it do

A

Virulence determinant for invasion and spread

When released, binds free iron for bacterial uptake

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38
Q

DNase: what is it and what does it do

A

Virulence determinant for invasion and spread

Lowers viscosity of secretions, so bacteria can spread

39
Q

Bacteremia

A

Presence of bacteria in bloodstream

40
Q

Neutrophil extracellular traps (NETs)

A

DNA and antimicrobial proteins and enzymes spit out of neutrophil to trap pathogens

41
Q

Intracellular bacterial pathogen examples (5)

A 
Chlamydia
Legionella
Mycobacterium tuberculosis
Salmonella
Listeria monocytogenes
42
Q

Listeria monocytogenes: Gram positive or negative, what type of pathogen

A

Gram positive

Food-borne pathogen

43
Q

What types of food can carry Listeria monocytogenes?

A

Produce
Raw (unpasteurized) milk
Cheese
Deli meat

44
Q

What type of extremophile is Listeria monocytogenes?

A

Psychrophile

45
Q

What can Listeria monocytogenes cross?

A

Placenta

46
Q

How does Listeria monocytogenes move inside host cells?

A

Polymerization of host actin

47
Q

Streptococcus pneumoniae causes what type of infection by forming what?

A 
Otitis media (infection of middle ear)
Forms biofilm
48
Q

Pseudomonas causes infection in what organ of what individuals by forming what?

A

Lung of cystic fibrosis patients

Forms biofilm

49
Q

Staphylococcus and Enterococcus cause what infection on what body part by forming what?

A

Endocarditis

Form biofilm on heart valves

50
Q

Streptococcus mutans (along with other bacteria) causes what condition by forming what?

A

Dental plaque

Forms biofilm

51
Q

Biofilms enable bacteria to evade innate, adaptive, or both immune systems?

A

Both

52
Q

Biofilms protect bacteria from what part of the adaptive immune system and what part of the innate immune system?

A

Adaptive: antibodies (can’t bind)
Innate: phagocytes (can’t engulf)

53
Q

How do biofilms protect from antibiotics?

A

Matrix and slow growth of microbes in biofilms inhibits antibiotics

54
Q

Toxins

A

Substances that damage host

55
Q

2 types of toxins and how they are differentiated

A

Exotoxin is made and released by bacterial cell

Endotoxin is part of bacterial cell

56
Q

4 types of exotoxin

A

Membrane disrupting
Superantigens
AB
Specific host site

57
Q

How do membrane-disrupting exotoxins function?

A

Form pores

58
Q

2 examples of pore-forming exotoxins

A

Leukocidins

Hemolysins

59
Q

Leukocidins form holes in what type of cells?

A

Leukocytes

60
Q

Hemolysins form holes in what type of cells for what purpose?

A

Red blood cells

Makes iron available to pathogens

61
Q

How do pores in host cell plasma membrane destroy host cells?

A

Hole in host cell plasma membrane causes swelling due to water rushing into cell and then causes cell to lyse

62
Q

Superantigens bind both ____ and _____. This causes what to happen?

A

MHC and TCR

Locks them in place

63
Q

Superantigens cause ____ cells to overexpress, releasing ____.

A

T cells

Cytokines

64
Q

Overexpression of T cells by superantigen causes failure of multiple ____.

A

Organs

65
Q

Toxic shock syndrome is caused by what type of exotoxins produced by what genus and species of bacteria?

A

Superantigen

Staphylococcus aureus

66
Q

AB exotoxins have what 2 subunits for what purposes?

A

A: toxic effect
B: binds target cell receptor

67
Q

Many AB exotoxins are ___-_____ _____. What does that mean?

A

ADP-ribosyl transferases

Remove ADP-ribose group from NAD and attach it to host cell protein, which is then inactivated or functions irregularly

68
Q

What bacteria causes diphtheria?

A

Corynebacterium diphtheriae

69
Q

Diphtheria AB exotoxin steps (5)

A
  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
Q

Cholera produces what type of exotoxin and is produced by what genus and species?

A

AB exotoxin

Vibrio cholerae

71
Q

What kind of toxin is cholera AB toxin?

A

Enterotoxin (attacks intestine)

72
Q

Botulinum toxin is an ____ _____ produced by what genus and species?

A

AB neurotoxin

Clostridium botulinum

73
Q

Cholera AB toxin steps (5)

A
  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
Q

Botulinum toxin blocks release of ____ at ____ ____. What does this mean for the host?

A

Acetylcholine
Neuromuscular junction
Muscules can’t contract, causing flaccid paralysis

75
Q

Botulinum toxin is used to make ____. It can be used to treat ____, _____, and _____ ____.

A

Botox

Migraines, spasms, excessive sweating

76
Q

Antibodies can also be called what? What do they do to exotoxins?

A

Antitoxin

Neutralize toxicity

77
Q

Are exotoxins stable or unstable? If they lose toxicity, they remain _____.

A

Unstable

Remain antigenic

78
Q

Toxoid: definition, basis of what kind of vaccines, example vaccine that is this type

A

Inactivated toxin that can still elicit an immune response
Toxoid vaccine
DTaP (diphtheria, tetanus, pertussis)

79
Q

Example endotoxin

A

LPS (lipid A portion specifically) of Gram negative bacteria

80
Q

How does LPS function as an endotoxin?

A

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
Q

The actions of endotoxin LPS can lead to what?

A

Septic shock

82
Q

Sign of septic shock

A

Petechia (red spots coming from leaky blood vessels)

83
Q

Septic shock is a common cause of death where?

A

Intensive care units

84
Q

Sepsis: definition and symptoms

A

Systemic response to microbial infection
Elevated temperature, heart, and respiratory rate
Elevated leukocyte count

85
Q

Shock

A

Sepsis with hypotension

86
Q

Septicemia

A

Systemic disease in which microbes multiply in blood

87
Q

Type III secretion: infection by ____

A

Injection

88
Q

Type III secretion is used by many Gram ____ bacterial ___ and ____ pathogens

A

Negative

Plant and human pathogens

89
Q

Type III secretion is carried out by what bacterial structure?

A

Injectisome

90
Q

3 parts of injectisome

A

Basal body
Needle
Pore

91
Q

Injectisome injects what?

A

Effector proteins

92
Q

2 targets for type III effectors

A

Host cell cytoskeleton (actin)

Host cell signaling (NFkappaB)

93
Q

How do type III effectors target host cell cytoskeleton (actin)?

A 
Promote invasion
Block phagocytosis (macrophages need actin to phagocytose)
94
Q

How do type III effectors target host cell signaling (NFkappaB)?

A

Block cytokine production
Promote intracellular survival
Induce apoptosis

Microbiology (24 decks)

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