Elevated cerebrospinal fluid levels of glutamate in children with bacterial meningitis as a predictor of the development of seizures or other adverse outcomes

Objective: Evaluation of elevated cerebrospinal fluid levels of glutamate in children with bacterial meningitis as a predictor of seizures or other adverse outcomes. Design: Prospective cohort study with controls. Setting: A 36-bed pediatric intensive care unit and primary pediatric referral center. Patients: From 1999 to 2001, a total of 55 patients, between the ages of 0 and 18 yrs, with lumbar punctures performed for suspected meningitis. Measurements and Main Results: A total of 23 patients had bacterial meningitis confirmed by cerebrospinal fluid/blood culture and elevated cerebrospinal fluid white blood cell counts, and 32 patients, who tested negative, were included as controls. The median age for the patients with meningitis was 1.0 yr (range, 0.0 -15.2 yrs), and in the culture-negative group (control group), the median age was 0.3 yrs (range, 0.0 -17.0 yrs). The average cerebrospinal fluid white blood cell count was 2707 ± 3897 in the group with bacterial infection, whereas in the control group, the average was 148 ± 259 (p < .01). Patients with bacterial meningitis had a mean cerebrospinal fluid glutamate level of 60.5 ± 88.4 mol/L, whereas the mean cerebrospinal fluid glutamate level in the control group was 4.9 ± 11.0 mol/L (p < .01). However, only 10 of 23 children with bacterial meningitis had a second lumbar puncture performed during the study. There was no correlation between the cerebrospinal fluid white blood cell count and cerebrospinal fluid glutamate levels in either the study or control patients. None of the control patients developed seizures or neurologic deficits, despite some patients having elevated glutamate levels. However, four patients with bacterial meningitis developed seizures after admission to the hospital, and ten were discharged with at least some neurologic sequelae attributable to their infection. Two out of the three who developed seizures and had a repeat lumbar puncture demonstrated persistent elevation of cerebrospinal fluid glutamate levels. In addition, 70% of patients (7 of 10) with Streptococcus pneumoniae meningitis developed neurologic complications (p = .04). Conclusions: Bacterial meningitis in children causes an increase in cerebrospinal fluid glutamate that in many cases persists over time. However, in this limited study, neither higher nor persistent elevation of cerebrospinal fluid glutamate levels is predictive of which patients might develop seizures or other apparent immediate adverse outcomes after invasive infection. The responsible organism seems to have far more significance in predicting the development of adverse sequelae.