Difference Between Endo and Exotoxins


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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

Reply to Peer:

Unit 4 DB4

Michael Spencer posted Sep 17, 2021 1:45 PM

Hello class,

            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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