[Rapid diagnosis of gram-negative bacteriuria with endotoxin-specific chromogenic test]

Limulus amebocyte lysate test is a simple, yet sensitive laboratory method for detecting endotoxin. Although the specificity of the test was questioned, we recently solved this problem by removing a (1----3)-beta-D-glucan-sensitive factor G from the lysate (Endospecy, Seikagaku Kogyo Co., Ltd, Tokyo). In this study, we have established a method for the determination of endotoxin urine in using Endospecy. An aliquot of 0.2 ml of Endospecy dissolved in 4.4 ml of 0.1 mol/l Tris-HCl buffer (pH 8.0) was added to 5 microliter of urine sample. The mixture was incubated at 37 degrees C for 30 min. After diazo-coupling, absorbance was measured at 545 nm. The standard curve using Escherichia coli 0111: B4 endotoxin showed a good linearity. The addition-recovery test of various endotoxins showed nearly 100% recovery. Normal urine contained less than 60 pg/ml of endotoxin. Urine from patients with Gram-negative bacteriuria showed definitely high values, whereas urines infected either with Gram-positive bacteria or with fungi all showed nearly normal values. This method will be useful as a rapid and reliable test for the diagnosis of urinary tract infection with Gram-negative bacteria.