Investigate the Activity of Endotoxin in Severe Sepsis

Endotoxin is the major mediator of gram-negative bacteria which cause the systemic inflammation and result in microcirculatory dysfunction, and it leads to multiple organ dysfunction and death in patients with severe sepsis and septic shock.

The goal of this study is to measure the endotoxin activity of patients with severe sepsis and septic shock at certain time points, and furthermore, to compare the difference of endotoxin activity among different pathogens, infection source, and antibiotics. The study will enroll severe sepsis and septic shock patients.

The endotoxin activity will be measured by Limulus Amebocyte Lysate (LAL) test. Limulus Amebocyte Lysate (LAL) test will be used to detect and quantify serum level of endotoxin. The critical component of the LAL reagents used in endotoxin tests is derived from blood cells (amebocytes) of the horseshoe crab, Limulus polyphemus. It contains the proteins of the blood clotting mechanism, which is triggered by endotoxins. LAL reagents are primarily used to test for endotoxins in injectable pharmaceuticals, biological products, and medical devices. They are also used in renal dialysis centers and a wide range of other applications. LAL tests are described in the Bacterial Endotoxins Test chapter in the United States Pharmacopeia (Chapter 85) and in the equivalent chapters in the European Pharmacopoeia (Chapter 2.6.14) and the Japanese Pharmacopoeia (Part I, General Tests, No. 6). We will adopt the chromogenic method as purchased from the Associates of Cape Cod Inc. (ACC). The LAL reagent is formulated with a synthetic substrate which gives a yellow color when acted upon by endotoxin activated enzyme. The test is read at 405 nm, usually in a microplate reader. The severity of multiple organ dysfunction and 28-day mortality will be followed up.