Usefulness of endotoxin-specific limulus test for the measurement of endotoxin in cerebrospinal fluid in diagnosis of bacterial meningitis

Abstract

Using a new endotoxin-specific chromogneic limulus assay (Endoscopy test), endotoxin concentrations were measured in 93 specimens of cerebrospinal fluid (CSF) from 66 pediatric patients. Eighteen patients were diagnosed as having menigitios. Of these, 6 cases (group A) with gram-negative meningitis proven by culture had high CSF endotoxin concentrations of 115.3, (82-133) (median, range) pg/ml. Ten cases (group B) with gram-positive or aseptic meningitis had endotoxin concentrations of 2.15 (0.1-3.6) pg ml. Other 2 cases with bacterial meningitis (group C), in whom no pathogen was detected, had CSF endotoxin concentrations of more than 100 pg/ml. Four cases with encephalitis (group D) and 45 cases with non-meningitis or non- encephalitis (group E), had CSF endotoxin concentrations of less than 5 pg/ml. Despite a negative culture after antibiotic treatment in group A patients, endotoxin was cleared slowly from the CSF. A clearing of endotoxin from CSF was followed by alleviation of fever with a more gradual decline in CRP values. In 2 cases of group C, the negative bacterial culture appeared to be attributable to the previous treatment with antibiotics. However, these patients had high CSF endotoxin levels, indicating gram negative bacterial meningitis. In 17 CSF specimens from 5 patients of group A, in whom Haemophilus influenzae was detected on admission, an additional a latex agglutination test for the detection of H. influenzae polysaccharide antigen was performed. Only 3 specimens from 3 patients with CSF endotoxin concentrations of more than 80 pg/ml had a positive agglutination test. These results suggest that quantitation of endotoxin concentrations is useful for the diagnosis of gram-negative meningitis. And also, the clearance of endotoxin from CSF during treatment appears to be useful in determining the timing of when antibiotic should be stopped.