Catalse + bugs and toxins Flashcards
Which disease predisposes to infection with catalse + bugs?
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
How can endotoxin cause DIC?
Activates tissue factor, which starts the coagulation cascade
Cholera toxin most similar to:
LT toxin of ETEC
Pertussis toxin
(Increase cAMP)
Streptolysin O most similar to:
Alpha toxin of C. perfringens
(Degrade cell membranes)
Describe the two different exotoxin A’s
Pseudomonas exotoxin A = inhibits EF-2 = inhibits protein synthesis
GAS exotoxin A = superantigen = shock
What causes HUS seen in EHEC and Shigella toxin?
Shiga toxin causes release of cytokines that induce HUS
What 3 things does endotoxin activate?
Macrophages, complement, tissue factor/coagulation cascade
MOA tetanospasmin
Cleaves SNAREs = inhibit release of glycine and GABA from Renshaw cells in SC = spasticity, risus sardonicus, lockjaw
MOA pertussis toxin
Inactivates Gi = overactivity of cAMP = inhibits phagocytosis = permits survival of bug
MOA alpha toxin
Phospholipase = degrades cell membranes = myonecrosis + double zone of hemolysis on BAP
(C. perfringens)
Lysogenic phage-encoded toxins
Shiga toxin
Botulinum toxin
Cholera toxin
Diphtheria toxin
Erythrogenic toxin of GAS
Overactivates cAMP
LT of ETEC (directly)
Cholera toxin (by permanently activating Gs)
Pertussis toxin (by inactivating Gi)
Mechanism of action of Shiga-like toxin/Shiga toxin
Inhibits 60S ribosome by removing adenine from rRNA
MOA streptolysin O
Degrades cell membranes = lyses RBCs
Toxins that inhibit release of NT
Botulinum toxin
Tetanospasmin
MOA superantigens
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
What do macrophages activated by LPS produce? Function of these products?
TNFalpha = hypotension, fever
IL-1 = fever
NO = hypotension
People with chronic granulomatous disease are suspectible to which specific bugs?
Pseudomonas, Listeria, Aspergillus, Candida, E. coli, S. aureus, Serratia
Toxin that inhibits phagocytic activity
Pertussis toxin
If a bacteria is known to inhibit 60S ribosomal subunit, how can you know which bacteria it is?
Must be Shigella or EHEC - Shigella invades, EHEC doesn’t
Catalse + bugs
Pseudomonas, Listeria, Aspergillus, Candida, E. coli, S. aureus, Serratia
Mimics cAMP
Edema factor of anthrax
MOA LT
Overactivates cAMP = increased Cl- secretion into lumen = H20 follows = watery diarrhea
(ETEC)
Diphtheria toxin most similar to
Exotoxin A of Pseudomonas
Protein A vs. exotoxin 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
MOA botulinum toxin
Cleaves SNAREs = inhibits release of ACh at NMJ = flaccid paralysis
Causes beta-hemolysis on BAP
Streptolysin O of GAS
Superantigens causing shock
TSST-1 (S. aureus)
Exotoxin A (GAS)
Fever + rash + shock
Toxic shock = exotoxin A (GAS) or TSST-1 (S. aureus)
Mechanism of action of exotoxin A and diphtheria toxin
Inhibit EF2 = inhibit protein synthesis
Toxins that lyse cell membranes
Alpha toxin (C. perfringens)
Streptolysin O (GAS)
3 exotoxins that inhibits protein synthesis
Exotoxin A (P. aeruginosa)
Diphtheria toxin
Shiga toxin/Shiga-like toxin (Shigella/EHEC)
Toxin of scalded skin syndrome
Exfoliative toxin of S. aureus
Preformed exotoxin
S. aureus food poisoning (enterotoxin)
Two component toxins: A (attaches ADP-ribosylate to disrupt cell membrane) and B (binding and phagocytosis)
Toxins that inhibit protein synthesis = diphtheria toxin, Shiga toxin, exotoxin A
Cholera toxin
Pertussis toxin
LT of ETEC
MOA edema factor
MIMICS cAMP
(B. anthracis)
What is function of catalse?
Degrades H2O2 produced via NADPH oxidase reaction before it is converted into microbiocidal products via MPO
Generalized vs. specialized transduction
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
MOA ST
Overactivates cGMP = decreased NaCl and H2O resorption = watery diarrhea
ASO
Anti-streptolysin O antibodies = diagnosis of rheumatic fever
(GAS)
Causes double zone of hemolysis on BAP
C. perfringens alpha toxin (PLase)
4 exotoxins that increase fluid secretion
Edema factor (anthrax)
ST and LT (ETEC)
Cholera toxin
Overactivated cGMP
ST of ETEC
Protease toxins
Botulinum toxin
Tetanospasmin
MOA Cholera toxin
Permanently activates Gs = overactive cAMP = Cl- and H2O efflux
