Septic shock is a very serious consequence of a bacterial infection. Bacteria that are classified as gram negative rod-shaped most commonly cause septic shock. Examples of gram negative rod-shaped bacteria that cause septic shock are Escherichia coli, Klebsiella, Enterobacter, Proteus, and Pseudomonas. These bacteria all produce a factor that initiates septic shock. This factor is called lipopolysaccaride or endotoxin. LPS is composed of long chains of sugar molecules with fatty acids attached to them. LPS is shed by the bacteria and makes its way into the bloodstream. Once in the bloodstream, LPS binds to white blood cells that trigger the immune system to begin destroying the bacteria.
Bruce Beutler et. al. reported, in the December 11, 1998, issue of the journal Science, finding a gene in mice that controls this early response of our immune systems to these LPS shedding bacteria. The gene is called Tlr4, for "toll-like receptor 4." Mutations in the Tlr4 gene permit bacteria to grow unchecked, and when the immune system does react, it does so violently and releases large amounts of immune substances into the bloodstream. This violent reaction causes the blood pressure to go very low (shock), the formation of blood clots, and spontaneous bleeding. Shock, clot formation, and bleeding, even though the blood is clotting, are the major signs of septic shock. Over 1 million people in the world and 20,000 people in the United States die each year from septic shock. There is no effective treatment for septic shock, and about half of all cases of septic shock end in death.
A human gene similar to the mouse Tlr4 gene has been found and may help researchers to determine what people have mutations in this gene. Those people with mutations in this gene may be more likely to develop septic shock and ways could be developed to prevent them from getting gram negative bacterial infections.
Knowledge is Power. For more power go to:
The Howard Hughs
Medical Institute's news release.
Healthanswers information on septic shock.
Take Care and Think Microbiologically!
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