Objective:To evaluate the diagnostic usefulness of effluent endotoxin by Li
mulus amoebocyte lysate (LAL) assay in gram-negative peritonitis patients o
n continuous ambulatory peritoneal dialysis (CAPD) therapy.
Design: Prospective study with patients serving as their own controls. Stan
dard microbiologic work up and endotoxin analysis of effluents (night dwell
) were done during the pre- and posttreatment phases.
Setting: Specimens from three teaching hospitals were processed and tested
at a common center. Patients were left for treatment at their respective ce
nters without intervention.
Patients: 32 clinical peritonitis and 40 infection-free CAPD patients were
studied.
Results: 75% (n = 24) of cultures were positive: 41.6% (n = 10) gram-negati
ve and 58.4% (n = 14) grampositive bacteria. Effluents of pre- and posttrea
ted gram-negative cultures had endotoxin levels of 1.53 +/- 0.169 and 0.214
+/- 0.085 endotoxin units (EU)/mL, respectively (p < 0.0001); pre- and pos
ttreated gram-positive levels of 0.102 +/- 0.06 and 0.122 =/- 0.052 EU/mL,
respectively (p > 0.05); pre- and posttreated culture-negative peritonitis
levels of 0.110 +/- 0.025 and 0.087 +/- 0.031 EU/mL, respectively (p > 0.05
); peritonitis-free effluents contained 0.117 +/- 0.079 EU/mL. The diagnost
ic specificity and the sensitivity of LAL assay were 100% and 98.2% respect
ively.
Conclusion: Where initial microbiological work-up cannot demonstrate a path
ogen, effluent endotoxin determined by quantitative LAL assay is a useful m
arker for diagnosis and management, within safe time limits, of gram-negati
ve peritonitis in CAPD patients.