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Step One R&M > Catalse + bugs and toxins > Flashcards

Catalse + bugs and toxins Flashcards

1
Q

Which disease predisposes to infection with catalse + bugs?

A

Chronic granulomatous disease; lacking NADPH oxidase but bugs bring in H2O2 which is converted by MPO into free radicals so they can still kill bugs unless they produce catalase that breaks down H2O2

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1
Q

How can endotoxin cause DIC?

A

Activates tissue factor, which starts the coagulation cascade

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1
Q

Cholera toxin most similar to:

A

LT toxin of ETEC

Pertussis toxin

(Increase cAMP)

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1
Q

Streptolysin O most similar to:

A

Alpha toxin of C. perfringens

(Degrade cell membranes)

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2
Q

Describe the two different exotoxin A’s

A

Pseudomonas exotoxin A = inhibits EF-2 = inhibits protein synthesis

GAS exotoxin A = superantigen = shock

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3
Q

What causes HUS seen in EHEC and Shigella toxin?

A

Shiga toxin causes release of cytokines that induce HUS

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3
Q

What 3 things does endotoxin activate?

A

Macrophages, complement, tissue factor/coagulation cascade

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4
Q

MOA tetanospasmin

A

Cleaves SNAREs = inhibit release of glycine and GABA from Renshaw cells in SC = spasticity, risus sardonicus, lockjaw

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5
Q

MOA pertussis toxin

A

Inactivates Gi = overactivity of cAMP = inhibits phagocytosis = permits survival of bug

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5
Q

MOA alpha toxin

A

Phospholipase = degrades cell membranes = myonecrosis + double zone of hemolysis on BAP

(C. perfringens)

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6
Q

Lysogenic phage-encoded toxins

A

Shiga toxin

Botulinum toxin

Cholera toxin

Diphtheria toxin

Erythrogenic toxin of GAS

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7
Q

Overactivates cAMP

A

LT of ETEC (directly)

Cholera toxin (by permanently activating Gs)

Pertussis toxin (by inactivating Gi)

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8
Q

Mechanism of action of Shiga-like toxin/Shiga toxin

A

Inhibits 60S ribosome by removing adenine from rRNA

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9
Q

MOA streptolysin O

A

Degrades cell membranes = lyses RBCs

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10
Q

Toxins that inhibit release of NT

A

Botulinum toxin

Tetanospasmin

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11
Q

MOA superantigens

A

Bind MHC class II and TCR within proximity of antigen binding site = activates many, many T cells = massive release of IF-gamma and IL-2

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12
Q

What do macrophages activated by LPS produce? Function of these products?

A

TNFalpha = hypotension, fever

IL-1 = fever

NO = hypotension

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13
Q

People with chronic granulomatous disease are suspectible to which specific bugs?

A

Pseudomonas, Listeria, Aspergillus, Candida, E. coli, S. aureus, Serratia

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15
Q

Toxin that inhibits phagocytic activity

A

Pertussis toxin

16
Q

If a bacteria is known to inhibit 60S ribosomal subunit, how can you know which bacteria it is?

A

Must be Shigella or EHEC - Shigella invades, EHEC doesn’t

17
Q

Catalse + bugs

A

Pseudomonas, Listeria, Aspergillus, Candida, E. coli, S. aureus, Serratia

18
Q

Mimics cAMP

A

Edema factor of anthrax

20
Q

MOA LT

A

Overactivates cAMP = increased Cl- secretion into lumen = H20 follows = watery diarrhea

(ETEC)

20
Q

Diphtheria toxin most similar to

A

Exotoxin A of Pseudomonas

22
Q

Protein A vs. exotoxin A

A

Protein A is membrane-bound toxin of S. aureus that binds to the Fc region of IgG to inhibit complement

Exotoxin A from Pseudomonas inhibits EF-2 to inhibit protein synthesis OR superantigen of GAS

22
Q

MOA botulinum toxin

A

Cleaves SNAREs = inhibits release of ACh at NMJ = flaccid paralysis

23
Q

Causes beta-hemolysis on BAP

A

Streptolysin O of GAS

24
Q

Superantigens causing shock

A

TSST-1 (S. aureus)

Exotoxin A (GAS)

26
Q

Fever + rash + shock

A

Toxic shock = exotoxin A (GAS) or TSST-1 (S. aureus)

28
Q

Mechanism of action of exotoxin A and diphtheria toxin

A

Inhibit EF2 = inhibit protein synthesis

29
Q

Toxins that lyse cell membranes

A

Alpha toxin (C. perfringens)

Streptolysin O (GAS)

30
Q

3 exotoxins that inhibits protein synthesis

A

Exotoxin A (P. aeruginosa)

Diphtheria toxin

Shiga toxin/Shiga-like toxin (Shigella/EHEC)

31
Q

Toxin of scalded skin syndrome

A

Exfoliative toxin of S. aureus

33
Q

Preformed exotoxin

A

S. aureus food poisoning (enterotoxin)

34
Q

Two component toxins: A (attaches ADP-ribosylate to disrupt cell membrane) and B (binding and phagocytosis)

A

Toxins that inhibit protein synthesis = diphtheria toxin, Shiga toxin, exotoxin A

Cholera toxin

Pertussis toxin

LT of ETEC

35
Q

MOA edema factor

A

MIMICS cAMP

(B. anthracis)

36
Q

What is function of catalse?

A

Degrades H2O2 produced via NADPH oxidase reaction before it is converted into microbiocidal products via MPO

37
Q

Generalized vs. specialized transduction

A

Generalized = lytic phage = phage infects bacterium and takes up some of its DNA, which it injects into another bacterium

Specialized = lysogenic phage = viral DNA incorporates into bacterial genome = viral DNA excised with flanking bacterial DNA = injected into another bacterium

38
Q

MOA ST

A

Overactivates cGMP = decreased NaCl and H2O resorption = watery diarrhea

39
Q

ASO

A

Anti-streptolysin O antibodies = diagnosis of rheumatic fever

(GAS)

40
Q

Causes double zone of hemolysis on BAP

A

C. perfringens alpha toxin (PLase)

41
Q

4 exotoxins that increase fluid secretion

A

Edema factor (anthrax)

ST and LT (ETEC)

Cholera toxin

42
Q

Overactivated cGMP

A

ST of ETEC

44
Q

Protease toxins

A

Botulinum toxin

Tetanospasmin

45
Q

MOA Cholera toxin

A

Permanently activates Gs = overactive cAMP = Cl- and H2O efflux

Step One R&M (38 decks)

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