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 activates targeted cells including macrophages and neutrophils, and causes septic shock. But it is known that the conventional 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 sepsis 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) admitted 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 cutoff 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.

A Flowthrough Assay for Rapid Bedside Stratification of Bloodstream Bacterial Infection in Critically Ill Patients: a Pilot Study

“…Although there are other methods such as the endotoxin activity assay (EAA) or limulus amebocyte lysate (LAL) assay for detecting endotoxin, they are either not direct or limited in their application toward complex biological fluids, such as serum, plasma, and tissue homogenates. While EAA works on the principle of chemiluminescence by measuring the host's neutrophil respiratory burst activity in response to endotoxin (32), LAL is a chromogenic LPS detection assay, widely used in parenteral pharmaceutical preparations (33).…”

Outstanding Contributions of LAL Technology to Pharmaceutical and Medical Science: Review of Methods, Progress, Challenges, and Future Perspectives in Early Detection and Management of Bacterial Infections and Invasive Fungal Diseases

“…Importantly, measuring EAA levels can be rather useful for identifying patients expected to benefit the most from PMX-HP therapy. With regard to the correlation between EAA and the LAL assay, patients with Gram-positive bacterial infections were reported to have higher EAA values than controls and those with GNB infections, and there was no significant correlation between the two [ 60 ]. It is apparent that different mechanisms are responsible for these inconsistent results, and thus, further studies might be needed to clarify their clinical relevance.…”

If EAA Test Versus LAL Test is Always Clinically Better and Whether Any Test Always Relates to the Therapeutic Value of Hemoperfusion in Septic Shock Patients?

“…EAA test demonstrates equally high levels in both gram-negative sepsis and gram-positive sepsis (EAA: 0.56 vs. 0.44, P > 0.05 (4); 0.55 vs, 0.50, P > 0.05 (3)).…”