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Microbiology > Ch 15: Microbial Mechanisms of Pathogenicity > Flashcards

Ch 15: Microbial Mechanisms of Pathogenicity Flashcards

1
Q

Define pathogenicity

A
  • The ability to cause disease
  • A property of an organism that it either has or lacks
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2
Q

Define virulence

A
  • The extent of pathogenicity
  • A measurement of the degree of pathogenicity that can be assessed
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3
Q

What are the most common portals of entry for diseases? (3)

A
  1. Mucous membranes
  2. Skin (hair follicles, sweat glands, surface)
  3. Parenteral route (penetration or injury)
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4
Q

What is the preferred portal of entry for SARS-CoV-2?

A

Mucous membranes of the upper respiratory tract

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5
Q

What is ID50?

A

Infectious dose of a toxin or pathogen for 50% of the test population

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6
Q

What is LD50?

A

Lethal dose of a toxin for 50% of the test population

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7
Q

What is the preferred portal of entry for Bacillus anthracis (anthrax)?

A

Skin

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8
Q

How do microbes adhere to a host cell?

A

Adhesins or ligands on the microbe bind to receptors on host cells

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9
Q

What are biofilms?

A
  • Communities of adherent microbe
  • Adhere to most surface with organic matter, a mix of polysaccharides and proteins
  • Ex: dental plaque
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10
Q

What is the evolutionary benefit of capsulated bacteria?

A
  • Increase virulence
  • Prevent phagocytosis
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11
Q

What is the function of M protein in bacterial cell wall? Organism?

A
  • Resist phagocytosis
  • Streptococcus pyogenes
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12
Q

What is the function of Opa protein in bacterial cell wall? Organism?

A
  • Inhibits helper T cells
  • Neisseria gonorrhoeae
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13
Q

What is the function of Mycolic acid in bacterial cell wall? Organism?

A
  • Waxy lipid
  • Resists digestion
  • Mycobacterium tuberculosis
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14
Q

What are exoenzymes?

A

Enzymes that work outside the bacterium to increase virulence

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15
Q

What is the function of the exoenzyme coagulase?

A

Coagulate fibrinogen

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16
Q

What is the function of the kinase exoenzymes?

A

Digest fibrin clots

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17
Q

What are invasins?

A
  • Proteins that alter host actin to enter the host cell
  • Causes membrane ruffling
  • Ex: Salmonella
18
Q

How do pathogens damage host cells? (4)

A
  1. Deplete host’s nutrients
  2. Cause direct damage
  3. Synthesize toxins
  4. Cause immune reactions
19
Q

What does the DPT vaccine use as its delivery system?

A
  • Toxoid (inactivated toxin)
20
Q

What are exotoxins?

A
  • Toxins secreted by a microbe that target a specific structure on or in the host cell
21
Q

Do Gram+ or Gram- use exotoxins?

22
Q

Which type of toxin has a larger LD50?

23
Q

What type of biochemical are exotoxins?

24
Q

Do exotoxins or endotoxins cause fever?

A

Endotoxins

25
What type of biochemical are endotoxins?
Lipid A from cell wall of Gram- bacteria
26
Are exotoxins or endotoxins neutralized by antitoxins?
Exotoxins
27
How do A-B Exotoxins function?
* A = active toxin; inhibits protein synthesis * B = binds receptor on host cell; released
28
How do membrane-disrupting exotoxins function?
* Lyse host cell by: * Making protein channels in plasma membrane * Disrupting phospholipid bilayer
29
What are superantigens?
* Exotoxins carried by a prophage * Caus an intense immune response due to release of cytokines from host cells * Disables the host immune system
30
What are the major symptoms of superantigens? (6)
1. Fever 2. Nausea 3. Vomiting 4. Diarrhea 5. Shock 6. Death
31
Identify the toxin: * Lysogenic phage caries *tox* gene that encodes an A-B toxin * Causes severe skin lesion * Part of the DPT vaccine * Produced by *Corynebacterium diphtheriae*
Diptheria toxin
32
Identify the toxin: * Superantigen * Damages plasma membranes of capillaries in skin * Causes Scarlet Fever, characterized by red skin rashes * Produced by *Streptococcus pyogenes*
Erythrogenic toxin
33
Identify the toxin: * A-B exotoxin * Neurotoxin; inhibits acetylcholine at the neuromuscular junction * Flaccid paralysis * Produced by *Clostridium botulinum*
Botulinum toxin (aka Botox)
34
Identify the toxin: * A-B exotoxin * Neurotoxin; causes uncontrollable muscle contractions * Produced by *Clostridium tetani*
Tetanus toxin
35
Identify the toxin: * A-B exotoxin * Enterotoxin; B-subunit binds to epithelial cells * Causes cells to secrete fluids and electrolytes; severe diarrhea * Produced by *Vibrio cholerae*
Cholera toxin
36
Identify the toxin: * Superantigen * Responsible for toxic-shock syndrome * Interacts with MHC class II T-cell surface receptor * Produced by *Saphylococcus aureus*
Staphylococcal enterotoxin | (Toxin = yellow, Receptor = green)
37
Why do endotoxins cause fevers?
* Cause macrophages to make cytokines (IL-1, aka TNF-alpha) * Cytokines signal hypothalamus to release prostaglandins, which leads to fever
38
What is a LAL assay?
* Limulus amoebocyte lysate assay * Detects very small amount of **endotoxin** * Amoebocyte lysis produces clot * Source: horseshoe crabs
39
Explain cytopathic viral pathogenesis
* Shut-down of host macromolecular synthesis * Triggers apoptosis * Inclusion body formation: aggregates inside cell * Syncytium: fusion of cells * Common among enveloped viruses
40
Explain transformation in regard to viral pathogenesis
* Inhibition of apoptosis * Immortalization, loss of contact-inhibition * Can lead to cancer
41
What is the receptor for SARS-CoV-2? Where is it abundant?
* ACE2 * Abundant in Type II alveolar cells and gut epithelium
42
What are the most common causes of death in regard to SARS-CoV-2 infection?
1. Complications related to the kidneys 2. Myocardial injury

Microbiology (19 decks)

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