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Microbiology1 > 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?

A

Gram+

22
Q

Which type of toxin has a larger LD50?

A

Endotoxin

23
Q

What type of biochemical are exotoxins?

A

Protein

24
Q

Do exotoxins or endotoxins cause fever?

A

Endotoxins

25
Q

What type of biochemical are endotoxins?

A

Lipid A from cell wall of Gram- bacteria

26
Q

Are exotoxins or endotoxins neutralized by antitoxins?

A

Exotoxins

27
Q

How do A-B Exotoxins function?

A
  • A = active toxin; inhibits protein synthesis
  • B = binds receptor on host cell; released
28
Q

How do membrane-disrupting exotoxins function?

A
  • Lyse host cell by:
    • Making protein channels in plasma membrane
    • Disrupting phospholipid bilayer
29
Q

What are superantigens?

A
  • Exotoxins carried by a prophage
  • Caus an intense immune response due to release of cytokines from host cells
  • Disables the host immune system
30
Q

What are the major symptoms of superantigens? (6)

A
  1. Fever
  2. Nausea
  3. Vomiting
  4. Diarrhea
  5. Shock
  6. Death
31
Q

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
A

Diptheria toxin

32
Q

Identify the toxin:

  • Superantigen
  • Damages plasma membranes of capillaries in skin
  • Causes Scarlet Fever, characterized by red skin rashes
  • Produced by Streptococcus pyogenes
A

Erythrogenic toxin

33
Q

Identify the toxin:

  • A-B exotoxin
  • Neurotoxin; inhibits acetylcholine at the neuromuscular junction
  • Flaccid paralysis
  • Produced by Clostridium botulinum
A

Botulinum toxin (aka Botox)

34
Q

Identify the toxin:

  • A-B exotoxin
  • Neurotoxin; causes uncontrollable muscle contractions
  • Produced by Clostridium tetani
A

Tetanus toxin

35
Q

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
A

Cholera toxin

36
Q

Identify the toxin:

  • Superantigen
  • Responsible for toxic-shock syndrome
  • Interacts with MHC class II T-cell surface receptor
  • Produced by Saphylococcus aureus
A

Staphylococcal enterotoxin

(Toxin = yellow, Receptor = green)

37
Q

Why do endotoxins cause fevers?

A
  • Cause macrophages to make cytokines (IL-1, aka TNF-alpha)
  • Cytokines signal hypothalamus to release prostaglandins, which leads to fever
38
Q

What is a LAL assay?

A
  • Limulus amoebocyte lysate assay
  • Detects very small amount of endotoxin
  • Amoebocyte lysis produces clot
  • Source: horseshoe crabs
39
Q

Explain cytopathic viral pathogenesis

A
  • Shut-down of host macromolecular synthesis
  • Triggers apoptosis
  • Inclusion body formation: aggregates inside cell
  • Syncytium: fusion of cells
  • Common among enveloped viruses
40
Q

Explain transformation in regard to viral pathogenesis

A
  • Inhibition of apoptosis
  • Immortalization, loss of contact-inhibition
  • Can lead to cancer
41
Q

What is the receptor for SARS-CoV-2? Where is it abundant?

A
  • ACE2
  • Abundant in Type II alveolar cells and gut epithelium
42
Q

What are the most common causes of death in regard to SARS-CoV-2 infection?

A
  1. Complications related to the kidneys
  2. Myocardial injury

Microbiology1 (20 decks)

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