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Bacteriology > Lecture 9 - Bacterial Pathogenesis - Adherence, Colonisation > Flashcards

Lecture 9 - Bacterial Pathogenesis - Adherence, Colonisation Flashcards

1
Q 
What are the stages of bacterial pathogenesis?
1)
2)
3)
4)
5)
A

1) Enter the body
2) Colonise the host
3) Evade host defences
4) Multiply, disseminate in host
5) Cause damage to host

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2
Q

What is the advantage of Strep. pyogenes’ capsule?

A

Made of hyaluronic acid

Very similar to many host cell surfaces, therefore not readily detected by immune system

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3
Q

Feature of bacteria causing very persistent infection

A

Biofilm formation

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4
Q

How is a biofilm formed?

A

Bacteria aggregate, secrete ECM of protein, polysaccharides, DNA

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5
Q

How might a biofilm contribute to antibiotic resistance?
1)
2)

A

1) Bacteria in biofilm can become inert - antibiotics affect growing or dividing bacteria
2) Barrier between bacteria and antibiotic

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6
Q 
Where can biofilms be frequently found?
1)
2)
3)
4)
5)
A

1) Implants
2) Catheters
3) Artificial heart valves
4) Teeth
5) Contact lenses

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7
Q

Which bacterium often colonises catheters?

A

Pseudomonas aeruginosa

Enterococcus

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8
Q 
Stages of biofilm production
1)
2)
3)
4)
5)
A

1) Adhesion
2) Colonisation
3) Cell-cell adhesion
4) Proliferation
5) Maturation

Planktonic bacteria leave biofilm, adhere to another structure

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9
Q

Which bacteria most commonly cause biofilms on tonsils?

A

Staph. aureus

Haemophilus influenzae

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10
Q

Types of bacterial colonisation
1)
2)
3)

A

1) Loose association
2) Tight association
3) Invasion

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11
Q

Most accessible part of host cell

A

Glycocalyx

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12
Q

Function of b1 integrins

A

Attach cell cytoskeleton to extracellular matrix

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13
Q

Common bacterial target in GIT

A

M cells

Have much thinner layer of mucus covering them than other parts of GIT

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14
Q

What do bacterial adhesins normally target?

A

Polysaccharide structures

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15
Q

Example of host cell protein receptor often bound to by bacterial adhesins

A

Beta-1 integrin receptor

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16
Q

Two types of adhesins

A

1) Fimbrial adhesins (loose associations)

2) Afimbrial adhesins (outer membrane proteins)

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17
Q

Type of bacteria which most commonly have pili

A

Gram -

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18
Q

What do type I pili bind?

A

Mannose in glycoproteins

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19
Q

What do Pap pili do?

A

Bind Gal alpha(1-4)Gal in glycolipids

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20
Q

Requirements of Pap/Type I pili construction

A

Usher/chaperone system

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21
Q

Which bacterium often colonises catheters?

A

Pseudomonas aeruginosa

Enterococcus

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22
Q 
Stages of biofilm production
1)
2)
3)
4)
5)
A

1) Adhesion
2) Colonisation
3) Cell-cell adhesion
4) Proliferation
5) Maturation

Planktonic bacteria leave biofilm, adhere to another structure

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23
Q

Which bacteria most commonly cause biofilms on tonsils?

A

Staph. aureus

Haemophilus influenzae

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24
Q

Types of bacterial colonisation
1)
2)
3)

A

1) Loose association
2) Tight association
3) Invasion

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25
Q

How does pilin get moved from cytoplasm to cell surface?
1)
2)
3)

A

1) Sec is a channel which brings pilin from cytoplasm to periplasmic space
2) Pilin needs to form correct disulphide bonds, find chaperone, or else is degraded
3) Chaperone/protein complex binds usher, usher brings pilin from periplasmic space to cell surface. PIlin is incorporated into pilus

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26
Q

Function of b1 integrins

A

Attach cell cytoskeleton to extracellular matrix

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27
Q

Common bacterial target in GIT

A

M cells

Have much thinner layer of mucus covering them than other parts of GIT

28
Q

What do bacterial adhesins normally target?

A

Polysaccharide structures

29
Q

Example of host cell protein receptor often bound to by bacterial adhesins

A

Beta-1 integrin receptor

30
Q

Which pili use a type II secretion system?

A

Type IV pili

31
Q

Type of bacteria which most commonly have pili

A

Gram -

32
Q

What do type I pili bind?

A

Mannose in glycoproteins

33
Q

What do Pap pili do?

A

Bind Gal alpha(1-4)Gal in glycolipids

34
Q

Requirements of Pap/Type I pili construction

A

Usher/chaperone system

35
Q

Function of usher protein

A

1) Usher binds chaperone/pilin complex in periplasmic space.

2) Pilin moved across cell membrane by usher, attached to pilus

36
Q

Structure of pilus

A

Composite fibre made up of six structural proteins

Helical array of pilin

37
Q

In pap and fim gene clusters, what is the function of major pilus subunit gene?

A

Pilin encoding

38
Q

Intimin
1)
2)

A

1) 94kDa outer membrane protein

2) Afimbrial adhesin

39
Q

How does pilin get moved from cytoplasm to cell surface?

A

1) Sec is a channel which brings pilin from cytoplasm to periplasmic space
2) Pilin needs to form correct disulphide bonds, find chaperone, or else is degraded
3) Chaperone/protein complex binds usher, usher brings pilin from periplasmic space to cell surface. PIlin is incorporated into pilus

40
Q 
Features of type IV pili
1)
2)
3)
4)
A

1) Don’t use usher/chaperone system of transport
2) Usually polar location
3) Can form bundles
4) Play a role in inter-bacterial interactions, host-cell mucosal surface adhesion, twitching motility

41
Q

Relationship between Arp2/3, N-WASP and Nck

A

Nck joins Arp2/3 and N-WASP to actin

42
Q

What is twitching motility?
1)
2)
3)

A

1) Different motility to runs and tumbles
2) Bacteria attach, retract pili to move
3) Leading rafts are forwardmost groups of bacteria

43
Q

Which secretion system do type IV pili use?

A

Type II secretion system

44
Q

Which pili use a type II secretion system?

A

Type IV pili

45
Q

Is Bordatella pertussis G+ or G-?

A

Gram -

46
Q

Example of bacterium that uses afimbrial adhesion

A

B. pertussis

47
Q

Most important afimbrial adhesin in B. pertussis

A

Filamentous haemagglutinin

48
Q

Features of filamentous haemagglutinin
1)
2)

A

1) 220kDa protein
2) Contains RGD motif - RGD motif found in human cells, binds fibronectin
3) Most important afimbrial adhesin in B. pertussis

49
Q

Bacteria causing attaching and effacing lesions

A

EPEC

EHEC

50
Q

Requirements for attaching/effacing lesions

A

1) Tir

2) Intimin

51
Q 
Tir
1)
2)
3)
4)
A

1) Translocated intimin receptor
2) Secreted by bacteria, inserted into host cell membrane
3) Extracellular component binds intimin
4) Intracellular N- and C- termini bind host cytoskeleton

52
Q

Intimin
1)
2)

A

1) 94kDa outer membrane protein

2) Afimbrial adhesin

53
Q

Function of Tir intracellular regions

A

Disrupt normal actin trafficking

Cause accumulation of actin below tir, forms a pedestal for bacterium

54
Q

Tir recruitment of actin is dependent on:
1)
2)
3)

A

1) Nck
2) N-WASP
3) Arp2/3

55
Q

Relationship between Arp2/3, N-WASP and Nck

A

Nck joins Arp2/3 and N-WASP to actin

56
Q

Is EHEC virulent without tir and intimin?

A

No

57
Q

Tir structure

A

Hairpin loop-like structure

58
Q

Structure of type 3 secretion system

A

Multiprotein apparatus
Proteins span both cell membranes
Filmentous structure outside of cell

59
Q

Which bacteria are T3SS found in?

A

Only in G-

60
Q

EPEC T3SS components

A

1) ESPA - Filamentous structure

2) ESPB/D - Insert into host cell membrane

61
Q

What is the function of ESPA?

A

Filamentous structure of T3SS in EPEC

62
Q

What are ESPB/D?

A

Parts of EPEC T3SS that insert into host cell membrane

63
Q

What is actin treadmilling?

A

Polymerisation and depolymerisation of actin

64
Q

What nucleates actin?

A

Arp2/3 complex

65
Q 
EPEC binding
1)
2)
3)
4)
5)
A

1) EPEC attaches loosely to host cell with bundle forming pilus (bfp)
2) T3SS inserts tir, intimin is expressed
3) EPEC binds to host cell with high affinity
4) Tir is phosphorylated by host cell kinase
5) Nck is activated. Recruits N-WASP and arp2/3 to polymerise actin

Bacteriology (29 decks)

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