Estimation of serum and CSF lactate as a diagnostic and prognostic marker of bacterial and aseptic meningitis in adults: experience from a tertiary care center

Abstract Background: Data on the utility of cerebrospinal fluid (CSF) lactate and serum lactate as prognostic markers for bacterial and viral meningitis remain scarce in the Indian setting. This study aimed to assess their effectiveness in differentiating bacterial from aseptic meningitis and in evaluating disease prognosis. Materials and Methods: A total of 60 patients diagnosed with meningitis were enrolled. Lumbar puncture was performed immediately upon admission, and patients were categorized into two groups: bacterial meningitis and aseptic meningitis. CSF and serum lactate levels were measured on Day 1 and Day 5. These values were compared across groups to determine their diagnostic utility and to assess their predictive value for outcomes such as recovery or death. Results: Mean CSF lactate levels were markedly higher in bacterial meningitis (12.0 mmol/L on Day 1 and 6.7 mmol/L on Day 5) than in viral meningitis (2.3 mmol/L on Day 1 and 1.7 mmol/L on Day 5). Among patients with bacterial meningitis, those who died had significantly higher CSF lactate levels (13.3 mmol/L) compared to survivors (5.8 mmol/L) ( P < 0.05). Mean serum lactate was also significantly elevated in bacterial meningitis (5.1 mmol/L vs. 2.2 mmol/L). Furthermore, serum lactate levels were higher in non-survivors (8.9 mmol/L) than in those who recovered (2.4 mmol/L) ( P < 0.05). Conclusion: Despite limited prior research, our findings indicate that both CSF and serum lactate are valuable markers for differentiating bacterial from aseptic meningitis and for predicting clinical outcomes.