Newly Developed Endotoxin Measurement Method (the Endotoxin Activity Assay) May Reflect the Severity of Sepsis

Abstract

Objectives: Endotoxin (ET) is a structural molecule of the Gram-negative bacilli extracellular membrance, which acti-vates targeted cells including macrophages and neutrophils, and causes septic shock. But it is known that the conven-tional ET measurement method has many problems; for example, a discrepancy between plasma ET concentration and clinical manifestration in the septic patients has been reported. The purpose of this study was to evaluate the usefulness of a newly developed method (Endotoxin Activity Assay (EAA)) to measure the ET activity (EA) in patients under sep-sis compared with the prior method of the limulus amebocyte lysate (LAL) assay and explore the association between EA levels and patients' severity. Method: We measured the EA levels in 40 patients (aged 63.5 +/− 17.7 years) admit-ted to the ICU. EA level was measured using a chemiluminometer (Autolumat LB953; EG & Berthold). Patients were divided into 5 groups: 1) control group; 2) systemic inflammatory response syndrome (SIRS) group; 3) sepsis (SIRS and infection) group; 4) severe sepsis group and 5) septic shock group. We then compared the EA level between each group and control group. We made the statistical evaluation by unpaired t test and significant difference was p < 0.05. Results: The EA levels were significantly increased as sepsis severity rises. The measured EA levels were (0.18 +/− 0.09), (0.33 +/− 0.19), (0.39 +/− 0.16), (0.65 +/− 0.25) and (0.78 +/− 0.34) in control, SIRS, sepsis, severe sepsis and septic shock groups, respectively. In the EA level measured by EAA, severe patients had a tendency to exceed the cut-off value. Conclusion: The EA levels were significantly correlated as patients' severity rise. Measuring EA levels on admittion to ICU may provide a mechanism to identify and target severe septic patients.