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32 Cards in this Set
- Front
- Back
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Bacterial endotoxins and exotoxins: Source?
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Exotoxin: Certain species of gram positive and gram negative bacteria, Endotoxin: Cell wall of most gram-negative bacteria
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Bacterial endotoxins and exotoxins: Secreted from cell?
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Exotoxin: Yes , Endotoxin: No
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Bacterial endotoxins and exotoxins: Chemistry
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Exotoxin: Polypeptide, Endotoxin: Lipopolysaccharide
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Bacterial endotoxins and exotoxins: Location of genes
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Exotoxin: Plasmid or bacteriophage, Endotoxin: Bacterial chromosome
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Bacterial endotoxins and exotoxins: Toxicity (fatal dosage)
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Exotoxin: High (fatal dose on the order of 1 microgram), Endotoxin: Low (fatal dose on the order of hundreds of micrograms)
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Bacterial endotoxins and exotoxins: Clinical effects
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Exotoxin: Toxin specific, Endotoxin: Fever and shock
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Bacterial endotoxins and exotoxins: Mode of action
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Exotoxin: Toxin specific, Endotoxin: Includes TNF and IL-1
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Bacterial endotoxins and exotoxins: Antigenicity
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Exotoxin: Induces high-titer antibodies called antitoxins, Endotoxin: Poorly antigenic
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Bacterial endotoxins and exotoxins: Vaccines
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Exotoxin: Toxoids used as vaccines, Endotoxin: No toxoids formed and no vaccine available
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Bacterial endotoxins and exotoxins: Heat stability
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Exotoxin: Destroyed rapidly at 60 degrees celsius (except Staphylococcal enterotoxin), Endotoxin: Stable at 100 degrees celsius for 1 hour
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Bacterial endotoxins and exotoxins: Typical bugs
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Exotoxin: Tetanus, botulism, diphtheria, Endotoxin: Meningococcemia, sepsis by gram negative rods
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Mechanism of superantigens
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1. Bind directly to MHC II and T cell receptor, 2. Large numbers of T cells are activated, 3. Stimulates release of IFN-gamma and IL-2
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Mechanism of ADP ribosylating A-B toxins
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Interfere with host cell function: B (binding) component binds to a receptor on surface of host cell, The toxin is endocytosed, A (active) component attaches an ADP-ribosyl to a host cell protein, That protein's function is altered.
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List of bugs that release superantigens
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Staphylococcus aureus, Streptococcus pyogenes
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List of bugs that release ADP ribosylating A-B toxins
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Corynebacterium diphtheriae, Vibrio cholerae, E. coli, Bordetella pertussis
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What to know about exotoxins released by Staphylococcus aureus
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Superantigens: TSST-1 causes toxic shock syndrome (fever, rash, shock). Enterotoxins cause food poisoning.
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What to know about exotoxins released by Streptococcus pyogenes
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Scarlet fever (superantigen): Erythrogenic, Causes toxic shock-like syndrome, Streptolysin O (hemolysin). The antigen for ASO antibody is found in rheumatic fever
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What to know about exotoxins released by Corynebacterium diphtheriae
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ADP ribosylating A-B toxin (similar to Pseudomonas exotoxin A), Encoded by beta-prophage, Disease: Pseudomembranous pharyngitis (grayish-white membrane) with lymphadenopathy, Mechanism: Inactivates elongation factor 2 (EF-2) Mnemonic: ABCDEFG
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What to know about exotoxins released by Vibrio cholerae
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A-B toxin ADP ribosylates Gs protein thus, Permanently activates Gs protein, Constant stimulation of adenylyl cyclase which, Increases pumping of Cl into gut, H2O follows it, Leads to rice water diarrhea
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What to know about exotoxins released by E. coli
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E.coli 0157:H7 produces Shiga toxin. ADP ribosylating A-B toxins, Heat-labile: Permanent activation of adenylyl cyclase (cholera-like mechanism) leading to watery diarrhea, Heat-stabile: Stimulates guanylate cyclase, Mnemonic: Labile like the Air
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What to know about exotoxins released by Bordetella pertussis
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1. ADP ribosylating A-B toxin, 2. Permanently disables Gi, 3. Constant stimulation of adenylate cyclase, 4. Causes whooping cough, 5. Also inhibits chemokine receptor causing lymphocytosis
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What to know about exotoxins released by Clostridium perfringens
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alpha toxin (aka lecithinase) causes: 1. gas gangrene, 2. myonecrosis, 3. hemolysis (See double zone of hemolysis on blood agar.), PERFringens PERForates a gangrenous leg.
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What to know about exotoxin released by Clostridium botulinum
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Properties: 1. Preformed, 2. Heat-labile Mechanism: Blocks the release of acetylcholine causing: 1. anticholinergic symptoms 2. CNS paralysis (especially cranial nerves), 3. Floppy baby syndrome - BOTulinum is from bad BOTtles of food and honey
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What to know about exotoxins released by Clostridium tetani
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Blocks the release of inhibitory neurotransmitter glycine from Renshaw cells in the spinal cord. Causes "lockjaw"
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What to know about exotoxins released by Bacillus anthracis
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1 toxin in the toxin complex is edema factor, an adenylate cyclase
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What to know about exotoxins released by Shigella
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Shiga toxin (also produced by E.coli 0157:H7). Cleaves host cell rRNA. Also enhances cytokine release causing hemolytic uremic syndrome.
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Endotoxin: What is it and where is it found?
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Lipopolysaccharide found in the outer membrane of gram-negative bacteria. Heat stable.
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Endotoxin: What does it activate and what do they release?
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1. Macrophages (IL-1, TNF, Nitric oxide), 2. Alternative complement pathway (C3a, C5a), 3. Hageman factor (Coagulation cascade)
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What mediators are released when endotoxin activates macrophages, and what do they do?
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1. IL-1: Fever, 2. TNF: Fever and Hemorrhagic tissue necrosis, 3. Nitric Oxide: Hypotension (shock)
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What mediators are released when endotoxin activates the alternative complement cascade, and what do they do?
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1. C3a: Hypotension and edema, 2. C5a: Neutrophil chemotaxis
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What mediators are released when endotoxin activates Hageman factor, and what do they do?
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Coagulation cascade: Disseminated intravascular coagulopathy
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What to know about exotoxins released by S. pyogenes
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Streptolysin O is a hemolysin, antigen for ASO antibody in rheumatic fever
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