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2.2 Microbiology > Toxins - Functions > Flashcards

Toxins - Functions Flashcards

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1
Q

Exfoliatin toxin

A

Staphylococcal scalded skin syndrome
Produced by 5% of S. aureus
Absorbed into bloodstream and causes desquamation of skin
Acute exfoliation of skin following cellulitis
Act on desmosomes causing epidermal splitting

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2
Q

Toxic shock syndrome toxin

A

Causes toxic shock syndrome
20% of S. aureus produce it
8% mortality rate
Surgical would infections or super absorbant tampons
Fever, hypotension, multi-system shut down, organ failure, toxic shock

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3
Q

What does coagulase do?

A

Binds to fibrinogen on cell surfaces

This converts fibrinogen to fibrin

This produces fibrin clots
- Causes agglutination of bacterial cells
- Promotes bacterial attachment
- White cells penetrate fibrin clots poorly

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4
Q

What does catalase do

A

neutralises the production of oxygen free radicals in phagocytes

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5
Q

What does protein A do?

A

A surface protein

Binds IgG molecules by the Fc region

IgG is bound in he wrong orientation

This disrupts opsonisation and phagocytosis

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6
Q

What are invasins in staph

A

Degradative enzymes promote spread in tissues
Staphylokinase
Hyaluronidase
Thermostable deoxyribonuclease

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7
Q

What does staphylokinase do?

A

Dissolves fibrin clots laid down by during inflammation to try to wall of the infection

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8
Q

What does hyaluronidase do

A

Hydrolyses matrix of connective tissue

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9
Q

What does thermostable deoxyribonuclease do

A

Releases nutrients for organism

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10
Q

What does Panton-valentine leukocidan do

A

Produces pores in leukocytes - common in community-associated infection

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11
Q

What does haemolysin do

A

Produces pores in red blood cell

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12
Q

Staph food poisoning toxin

A

Produced by 30-50% of S. aureus strains

Heat stable (100 degrees for 10 minutes)

Resistant to gastric and jejunal enzyme

Ingestion cause vomiting, as it acts on the vagus nerve endings in the stomach) and diarrhoea (stimulate intestinal peristalsis)

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13
Q

What do pili do

A

They adhere to nonciliated mucosal epithelium
Antigenic variation - immune evasion

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14
Q

What does the Opa protein do

A

Assist in epithelium binding
Assist in antigenic variation and allow for immune evasion

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15
Q

What does iron binding protein do

A

Facilitates multiplication and colonisation

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16
Q

What does IgA protease do

A

This cleaves IgA1
Degrades host IgA

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17
Q

What does Por protein do

A

Forms pores

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18
Q

What does Lipooligosaccharide do

A

Causes tissue damage
Inhibits mucocillary clearance (nasal infections)
Immune evasion
Antigenic diversity

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19
Q

What do fimbriae do

A

Attach to nonciliated epithelial cells
Antigenic switching - allows for immune evasion
Bind ciliated epithelium

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20
Q

What does the capsule do

A

Prominent antiphagocytic polysaccharide
Immune evasion

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21
Q

What is iron acquisition for

A

Multiplication

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22
Q

What does haemagglutinin do

A

Attachment to epithelium

23
Q

Pertussis toxin

A

Whooping cough
Lymphocytosis
Sensitisation to histamine
Activation of insulin producing causing hypoglycaemia

24
Q

Dermonecrotic toxin

A

Vasoconstriction
Ischemic necrosis

25
Q

Filamentous haemagglutinin

A

Facilitates attachment of bacteria to ciliated eipthelial cells

26
Q

Adenyl cyclase toxin

A

Decreases chemotaxis and phagocytosis of bacteria

27
Q

Tracheal cytotocin

A

Inhibits cillia movement and regeneration of damaged cells

28
Q

Choline binding protein A
(4)

A

Anchors the protein to the choline residues present in the cell wall

Responsible for remodelling the cell wall

Responsible for adhesion

Promotes invasion

29
Q

Autolysin LytA

A

Cell wall degrading protease
responsible for the release of S. pneumoniae virulence factors

30
Q

Pneumolysin

A

Cytolytic protein

Released by autolysin

Attacks cell membranes

Proinflammatory

Inhibits PMN

Activates complement

31
Q

M protein

A

Surface adhesin
Inhibits phagocytosis
Binds Fc portion of IgG
M types 1, 3, 12 and 28 are the most common isolates found in patients with shock and multiorgan failure
Strains lacking M protein are less virulent
Rheumatic heart disease
T-protein surface antigen
R-protein on some strains

32
Q

S. pyogenes toxins
(6)

A

Pyogenic exotoxins
Streptolysin O and S
Streptokinase
C5a peptidase
Streptodornases
Hyaluronidase

33
Q

Pyrogenic exotoxins

A

Cause various effects, including the rashes seen in scarlet fever and streptococcal toxic shock disease

34
Q

Streptolysin O and S

A

Damages mammalian cells, resulting in cell lysis and release of lysosomal enzymes

Lysis of RBCs, PMNs and platelets

35
Q

Streptokinase

A

Catalyses conversion of plasminogen to plasmin, causing lysis of clots, facilitating the rapid spread of organisms

36
Q

C5a peptidase

A

Inactivates complement component C5a

Cleaves the chemoattractant C5a

37
Q

Streptodornase

A

DNAses degrade the viscous DNA in necrotising tissue or exudates, aiding the spread of infection

38
Q

Hyaluronidase

A

Disrupts the organisation of ground substance, facilitating the spread of infection

Breaks down tissue hyaluronic acid

39
Q

Streptolysin S

A

Oxygen stable
Not antigenic
Leucocidal action

40
Q

Streptolysin O

A

Oxygen labile

Cytotoxic for red blood cells, neutrophils, platelets, cardiac tissue

Responsible for haemolysis that we see on blood agar

41
Q

SPE-A and SPE-C

A

Superantigens

Erythrogenic toxins

Similar to staph enterotoxins

Associated with invasive infections and toxic shock syndrome

42
Q

SPE-B

A

Cysteine protease

Associated with tissue destruction

43
Q

Pyocyanin

A

Interferes with the antioxidant defences in the lung

Facilitates oxidative damage to the lung epithelium

44
Q

Alginate slime

A

Matrix of biofilm formation

Impairs cillary function

45
Q

Elastase

A

Destruction of elastin

Cleaves IgG, IgA, Complement

Degrades surfactant proteins A and D

46
Q

Alkaline protease

A

Lyses fibrin

47
Q

Phospholipase C

A

A class of membrane-associated enzymes that cleave phospholipids

48
Q

Leukocidin

A

A type of cytotoxin or exotoxin

A pore-forming toxin that kills or destroys white blood cells by creating holes in their membranes

49
Q

Exotoxin A

A

A type of cytotoxin or exotoxin

A pore-forming toxin that kills or destroys white blood cells by creating holes in their membranes

50
Q

Exotoxin S

A

It impairs the function of phagocytic cells

51
Q

Four effector proteins of type III secretion system of Pseudomonas

A

ExoS
ExoT
ExoU
ExoY

52
Q

ExoU

A

Rapid destruction of host cell membranes
Is greater in P. aeruginosa isolated in hospital ICUs and burn unit

53
Q

ExoS

A

Relevant in patients with CF

2.2 Microbiology (60 decks)

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