Term
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Definition
| Typical definition is a product that by itself would cause disease. Note that factors that promote colonization or thwart the immune system would not be considered toxins if they do not cause disease by themselves. |
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Term
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Definition
| LPS found only on gram-negatives. Released when bacteria lyse, bind CD14 forming a complex that binds TLR-4. Activate immune system and clotting factors. |
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Term
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Definition
| Fever, hypoglycemia, hypotension/shock, activation of complement, impaired perfusion of organs, disseminated intravascular coagulation (DIC) resulting in occlusion of small vessels. Death may result from shock and massive organ dysfunction. |
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Term
| Mechanism of effects of endotoxin |
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Definition
| TLR-4 (which binds CD-14~LPS) is one of many pattern recognition receptors (PRRs) that bind pathogen associated molecular patterns (PAMPs) which stimulate cytokine production. Macrophages produce TNF and IL-1 when activated which are thought to mediate effects of endotoxin. |
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Term
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Definition
| Proteins produced by bacteria that are usually secreted, but sometimes released upon lysis. Many are enzymes, all function to inhibit, destroy activity or function of a critical biological process in the host |
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Term
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Definition
A-B subunit internalized
Single subunit internalized
Membrane-active
Superantigens |
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Term
| A-B subunit internalized exotoxins |
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Definition
B (binding) subunit mediates adherence of toxin complex to host cell surface and helps transmit A subunit into cell.
A (active) subunit possess the damaging enzymatic activity. Ex: diphtheria toxin, cholera toxin, anthrax toxin. |
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Term
| Single subunit internalized exotoxins |
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Definition
| One subunit with enzymatic activity that causes damage. Ex: B. pertussis adenylate cyclase toxin, C. difficile cytotoxins A and B. |
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Term
| Membrane-active exotoxins |
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Definition
| Various types of toxins that act at the membrane such as hemolysins (oligomerize to form membrane pores), membrane lytic enzymes, Staph. aureus exfoliative exotoxin that presumably disrupts cell-cell junctions etc. |
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Term
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Definition
| Mediate binding of T cell to antigen presenting cell nonspecifically (by binding outside of the usual binding domain). Causes mass activation of many T cells and release of cytokine, with resulting endotoxin-like syndrome. |
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Term
| Steps in treating toxin-mediated disease. |
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Definition
Identification: isolation of toxin-producing organism from patient or in some cases the exotoxin itself.
Treatment: antibiotic treatment of organism itself, sometimes may be able to neutralize the toxin itself with antitoxin serum (antibody) but is often not possible.
Prevention: some disease can be prevented by application of a toxoid (toxin rendered inactive by formalin or heat but still elicits immune memory). |
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