Measuring endotoxin with newly developed endotoxin scattering photometry

Introduction

Endotoxin scattering photometry (ESP) is a newly developed endotoxin assay. The mechanism of ESP is the same as for the turbidimetric method, which is a conventional endotoxin assay in Japan; however, ESP enables one to detect a very small amount of endotoxin within 1 hour. This is because ESP can detect the clotting enzyme product coagulin, which is the first appearance of limulus amebocyte lysate cascade evoked by endotoxin [1].

Methods

For measurement of clinical samples of endotoxin with ESP, three groups of patients were examined. The three groups were normal healthy volunteers (n = 14), patients with elective surgery (n = 10) and patients with sepsis (n = 19) who were admitted to the ICU between February and September 2007. Sepsis is defined by the American College of Chest Physicians/Society of Critical Care Medicine as systemic inflammatory response syndrome resulting from infection.

Results

Using endotoxin measurement with ESP, the value was higher in patients with sepsis (median, 20.7 pg/ml (interquartile range, 5.1–64.1 pg/ml)) than in patients with elective surgery (0.259 pg/ml (0.050–0.875 pg/ml)) and in normal healthy volunteers (0.073 pg/ml (0.031–0.345 pg/ml)).

Conclusion

Endotoxin could be detectable in every clinical sample by ESP, even though the turbidimetric method could detect positive for only 15% of patents with sepsis. These data suggest the potential value of measuring endotoxin with ESP for hunting down a hidden infection or an early manifestation for Gram-negative infection.