Differentiate between Endo- and Exotoxins. Using specific examples of bacteria, explain how the toxins they produce contribute to the virulence of those organisms.
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Unit 4 Discussion
Katie Wright posted Sep 17, 2021 8:01 PM
Endotoxins are only from gram negative bacteria. Found in the cell wall, the lipopolysaccharide represents an endotoxin and is released when the cell membrane is broken down. Endotoxins produce a weaker immune response, with typical signs/symptoms including a fever, chills, weakness, and aches. Salmonella is caused by Salmonella enterica, Typhoid fever is caused by a bacteria called Salmonella typhi and Neisseria meningitidis, or meningococcus, causes Meningitis. The toxins produced by these bacteria, as mentioned before, are in the cell wall and release during cellular lysis.
Exotoxins are found in both gram positive and negative bacteria. It is released from living cells that contain genetic coding on the chromosomes/plasmids/prophages. These are much more toxic than endotoxins and generate a strong immune response. Vibrio cholerae is an Enterotoxin that causes Cholera, Bacillus anthracis is a cytotoxin that causes Anthrax and Clostridium tetani is a neurotoxin that causes Tetanus. The toxins produced by V. cholerae target cellular chemical communication and cause Severe diarrhea. The toxins produced by B. anthracis target cellular chemical communication and cause hemorrhaging and pulmonary swelling. The toxins produced by C. tetani target cellular exocytosis and cause respiratory failure.
Pommerville, J. (2017). Fundamentals of Microbiology (11th Edition). Jones & Bartlett Learning. https://purdueuniversityglobal.vitalsource.com/books/9781284146790
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Unit 4 DB4
Michael Spencer posted Sep 17, 2021 1:45 PM
Endotoxins and exotoxins are microbes that have the ability to affect and possibly denature the functions of organisms and their normal cellular function. Exotoxins possess the chemical composition of protein and are secreted by a multitude of gram-negative and gram-positive bacterial species who excrete these toxins from living cells. Endotoxins on the other hand, house a lipopolysaccharide chemical composition and are an integral part of the cell wall which releases said toxins by the lysis of its bacterial cells. Exotoxins are heat sensitive molecules that can damage a host’s membranes and interfere with cellular function. Though endotoxins do not stimulate a strong immune system response, they have comparable toxic effects to exotoxins where they can produce symptoms such as fever, chills, body weakness, and muscle aches which can lead to circulatory system damage and endotoxin-shock. With exotoxins, the effects take on a more virulent nature possessing a high level of toxicity from small doses of the microbe causing a stronger immune system response, capable of producing death.
Bacterial examples of exotoxins are cytotoxins such as leucocidin and hemolysin that secrete toxins that kill cells, neurotoxins such as clostridium botulinum and C. tetani that excrete toxins that affect the nervous and musculoskeletal system in its host organisms, and enterotoxins which have the capability to affect the gastrointestinal tract in its hosts. Botulism, Diphtheria, and Cholera are representative diseases produced by exotoxins which possess a high virulence when entering host organisms. These three illnesses have a relatively high pathogenicity allowing them to spread rapidly and become deadly if not treated in a timely fashion. Endotoxin bacterial illnesses/diseases such as Salmonellosis, Typhoid fever, and Meningococcal meningitis produce forms of endotoxins that are not highly virulent but still can produce toxic symptoms such as diarrhea, fever, and stomach cramps in reference to salmonella; rashes, mental confusion, and vomiting in reference to meningitis which can also produce swelling of the meninges of the brain; and prolonged high-fever, physical body pain and discomfort, bloating, constipation, and nausea with Typhoid fever rendering endotoxins capable of producing toxic affects with a high level of pathogenicity but a low-to-mid-level of virulence and low toxicity unless received in large doses.
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