Detection of gram-negative bacteraemia in early sepsis by a quantitative chromogenic and kinetic endotoxin assay. The Study Group.

A kinetic chromogenic limulus test was carried out in order to investigate the possibility of a sensitive and specific detection of circulating endotoxin during the first 24 h of septic shock or severe sepsis in 76 patients. Two commercial kits, Whittaeker (W) and Chromogenix (C), were used. Blood culture was taken as a reference. At 1:10 plasma dilution (a currently used dilution in the end point limulus test) abnormal reaction kinetics were found in 13% and 41% of tests, for C and W respectively (P = 0.0008), resulting in unreliable results. Retesting plasma at a greater dilution, until the reaction kinetic was identical to calibration curve control values, gave similar results between the two kits and a better accuracy. Beyond a 0.5 EU mL-1 endotoxin level, the probability of Gram-negative bacteraemia was high (sensitivity = 0.53 and 0.47; specificity = 0.95 and 0.93 for C and W respectively). This kinetic limulus amoebocyte lysate (LAL) test may be useful in therapeutic decisions for treatment of endotoxaemia.