Endotoxins
Endotoxins
Endotoxins (pronunciation: /ˌɛndoʊˈtɒksɪn/) are a type of toxin that is present inside a bacterial cell and is released when the cell disintegrates. They are lipopolysaccharides (LPS) present in the outer membrane of the Gram-negative bacteria.
Etymology
The term "endotoxin" comes from the Greek words "endo," meaning "within," and "toxin," meaning "poison." This refers to the fact that endotoxins are released from within the bacterial cell.
Related Terms
- Exotoxins: These are toxins secreted by bacteria into the surrounding environment.
- Lipopolysaccharides: These are large molecules consisting of a lipid and a polysaccharide joined by a covalent bond; they are found in the outer membrane of Gram-negative bacteria, and elicit strong immune responses in animals.
- Gram-negative bacteria: These are a type of bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation.
Function and Effects
Endotoxins are heat-stable and can withstand temperatures up to 250 degrees Celsius. They are less toxic than exotoxins but can cause fever, changes in white blood cell counts, and shock when they enter the bloodstream. They can also lead to sepsis if not treated promptly.
Endotoxins are recognized by the immune system through a complex set of receptors, including Toll-like receptor 4 (TLR4). This recognition triggers an immune response, leading to the production of cytokines and other inflammatory mediators.
Detection and Treatment
Endotoxins can be detected using the Limulus amebocyte lysate (LAL) test. This test uses the blood of the horseshoe crab, which clots in the presence of endotoxins.
Treatment of diseases caused by endotoxins involves supportive care, such as fluids and medications to maintain blood pressure. Antibiotics are used to kill the bacteria, but they can also cause the release of more endotoxins as the bacteria die.
External links
- Medical encyclopedia article on Endotoxins
- Wikipedia's article - Endotoxins
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