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10 Cards in this Set
- Front
- Back
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What are exotoxins?
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They are proteins that are released by both G+ and G- bacteria. They are released by all the major G+ genera except Listeria monocytogenes, which produces endotoxin.
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Can Gram neg bacteria produce exotoxin?
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Vibrio cholera/E. Coli/ can excrete exotoxins. severe diseases caused by bacterial exotoxins include anthrax, as one example.
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What is a neurotoxin?
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they are exotoxins that act on the nerves or motor endplates to cause paralysis. Tetanus and Botulinum toxixs are examples.
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What is an enterotoxin?
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They are exotoxins that act on the gastro-intestinal tract to cause diarrhea. they inhibit NaCl resorption, activate its secretion, or kill epithelial intestinal cells. As a result, there is an osmotic pull of fluid into the intestine, resulting in diarrhea.
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What are the 2 disease manifestations of enterotoxins?
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Infectious diarrhea and Food poisoning. Examples of infectious diarrhea are Vibrio cholerae/E. coli/ campylobacter jejuni and Shigella dysenteriae. Bacteria will continue until organisms are destroyed by the immune system.
Food poisoning, bacteria grow in food and release enterotoxin in the food. Vomiting and diarrhea result for about 24 hours. Bacillus cereus and Staph. aureus are examples. |
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What are pyrogenic exotoxins/
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They stimulate the release of cytokines and can cause rash, fever and toxic shock syndrome. Examples are Staph. aureus and strep. pyogenes.
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What are tissue invasive exotoxins/
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These allow bacteria to destroy and tunnel through tissues. These include enzymes that destroy DNA, collagen, fibrin, NAD, RBC and WBC.
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What are exotoxin subunits?
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These are found in B. anthracis, Clostridium botulinum, Cl. tetani, Corynebacterium diptheria and Vibrio cholerae. their exotoxins are all composed of 2 polypeptide subunits bound together by disulfide bridges. One of these subunits, called B for binding or H, for holding binds to the target cell. The other subunit called A for action or L for laser, then enters the cell and exerts the toxic effect.
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How come treating a patient with a G- infection with antibiotics can worsen the patients condition?
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Lipid A endotoxin is very toxic and is released when the bacterial cell undergoes lysis. Endotoxin is shed in steady amounts from living bacteria. As the bacteria lyse, endotoxin is shed.
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How is an endotoxin different from a exotoxin?
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Endotoxin differs in that it is not a protein excreted from cells, but rather is a normal part of the outer membrane that sheds off. Endotoxin exists in G- bacteria only, with the exception of Listeria monocytogenes, which is G+.
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