Cerebrospinal fluid endotoxin concentrations in gram-negative bacterial meningitis

The limulus lysate assay was utilized to detect and quantitate endotoxin in cerebrospinal fluid from 232 patients with suspected meningitis. The assay was positive in initial specimens of CSF from all 86 patients with gram-negative bacterial meningitis and was uniformly negative in the remaining 146 patients with a variety of infectious and noninfectious processes. Endotoxin concentrations in initial specimens of CSF from patients with gram-negative meningitis ranged from 4 to 2,000 ng/ml. No correlation between initial CSF levels of endotoxin and initial clinical or laboratory variables of infection was noted. With antibiotic therapy, CSF concentrations of endotoxin fall rapidly to undetectable levels after five days.