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L4 Molecular Microbiology > Week 4: Virulence and pathogenicity 1 > Flashcards

Week 4: Virulence and pathogenicity 1 Flashcards

1
Q

Define the microbiome

A

the collection of all microbes, such as bacteria, fungi, viruses, and their genes, that naturally live on our bodies and inside us.

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2
Q

What is a pathogen?

A

– a harmful organism that produces a pathology
– Virulence, & virulence factors

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3
Q

What is a commensal organism?

A

– an organism that is part of the normal flora
– often mutualistic relationship
– endogenous

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4
Q

What is a opportunistic pathogen?

A

– an organism that causes infection when opportunity/change in
natural immunity arises
– e.g. in an immunocompromised individual

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5
Q

What is virulence?

A

The capacity of a microbe to
cause damage to the host.

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6
Q

Define a bacteria?

A

Prokaryotic, single celled
organisms

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7
Q

Define a virus?

A

Non-living, obligate parasites

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8
Q

Define a fungus?

A

Eukaryotic single to multi-cellular
infectious agents

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9
Q

Define a protozoa?

A

Amoeba, Plasmodium (malaria),
Toxoplasma

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10
Q

Define prions?

A

Amoeba, Plasmodium (malaria),
Toxoplasma

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11
Q

Define a parasite?

A

an organism that lives in or on an organism of another species (its host) and benefits by deriving nutrients at the other’s expense.

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12
Q

What is a virulence factor?

A

Component of a microbe that contributes to disease mechanism, not necessarily in all models
& not necessarily essential for survival

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13
Q

What is an invasin?

A

Enables organism to invade a host cell/tissue

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14
Q

What is an impedin?

A

Enables organism to avoid host defence mechanisms

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15
Q

What is an aggressin?

A

Causes damage to the host directly

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16
Q

What is a modulin?

A

Induces damage to the host indirectly

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17
Q

What is the adhesin of Staphylococcus aureus?

A

FnbpA

18
Q

What is the invasin of Staphylococcus aureus?

A

Coa

19
Q

What is the impedin of Staphylococcus aureus

A

Coa, Efb, Spa

20
Q

What is the aggressin of Staphylococcus aureus?

A

PVL

21
Q

What is the modulin of Staphylococcus aureus?

A

TSST-1

22
Q

What are 2 categories of prokaryotic pathogens?

A

Gram-positive/negative

23
Q

Is staphylococcus spp. Gram-positive or negative?

A

positive

24
Q

What conditions can S. aureus cause?

A

superficial lesions

boil to abscesses

life threatening

toxic shock
scalded skin syndrome
food poisoning

25
Q

What clinical conditions are associated with S. aureus?

A

boil
cellulitis
abscess
carbuncle

26
Q

What is SSTIs?

A

Skin & soft tissue infections

27
Q

What is a life-threatening disease caused by S. aureus

A

necrotising pneumonia

28
Q

What additional functions do cell wall associated proteins have?

A
  • Extra-cellular matrix (ECM)of host important target
  • Fibrinogen, Fibronectin & Collagen
  • Microbial surface component recognising adhesive
    matrix molecules (MSCRAMM)
29
Q

What adhesive matrix molecules do Microbial surface component recognising adhesive
matrix molecules (MSCRAMM) recognise?

A

– Share similar structures … (Two IgG-like domains)

– Fibrinogen binding proteins … (ClfA & ClfB)

– Fibronectin-binding proteins … (FnBPA)

– Collagen binding proteins … (Cna)

– Sialo-binding protein … (SdrC, SdrD, SdrE)

30
Q

Does fibronectin binding proteins play a role in invasion?

A

yes

31
Q

How do fibronectin binding proteins play a role in invasion?

A

FnBPA generates a strong
stable molecular bond
with soluble Fibronectin

  • Tandem ß-zipper
    interaction of FnBPA & Fn
  • Structural change allows
    binding to host cell.
  • Invasion involves bridging
    between FnBPs & a5b1
    integrins
32
Q

What are secreted adhesion molecules involved in?

A

Secreted proteins involved in adhesion and immune evasion

33
Q

What does S. aureus secrete/ decorated in?

A

SERAMs

34
Q

What are SERAMs?

A

Secreted expanded repertoire adhesion molecules
e.g. Extracellular adherence protein

35
Q

How are S. aureus defined?

A

S. aureus has been defined by its ability to coagulate plasma

36
Q

what are coagules?

A

Coagulase is tightly bound to the surface of the bacterium S. aureus and can coat its surface with fibrin upon contact with blood.

37
Q

What are coagules abbreviated to?

A

Coa

38
Q

How do coagules (Coa) work in S. aureus?

A
  • Coagulase (Coa)

– N-terminus binds prothrombin
– C-terminus Fg binding sites (5-8)
– Can bind Fg directly
– Staphylothrombin
– Cleaves Fg to fibrin
– Protective shield excludes immune
cells
– Reveals attachment site

39
Q

How does the extracellular Fg binding protein interact with Coa?

A

Extracellular Fg binding protein

– N-terminus 2 Coa like Fg domains

– C-terminus interferes with
complement

40
Q

What is an example of the multifunctional adhesion molecules of S. aureus?

A

Extracellular fibrinogen binding protein (Efb) one example

41
Q

What does secretion of Efb lead to?

A

Secretion of Efb leads to reduced complement activation
partly due to impaired AP C3 pro-convertase formation.

L4 Molecular Microbiology (53 decks)

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