The cerebrospinal fluid neutrophil to lymphocyte ratio is a sensitive biomarker for bacterial meningitis in children.

Background: The cerebrospinal fluid neutrophil-to-lymphocyte ratio (CSF NLR) as a diagnostic biomarker of bacterial meningitis has been reported in adult trials. The aim of this study was to evaluate the CSF NLR as a diagnostic biomarker of bacterial meningitis in children and to define an optimal CSF NLR concentration.

Methods: We performed a retrospective cohort study of children with clinical findings compatible with meningitis. CSF NLR was calculated as the ratio of neutrophil count to lymphocyte count in cerebrospinal fluid (CSF). Initial data included clinical, radiological, and laboratory diagnostics.

Results: We determined CSF parameters from children with infectious meningitis (n = 348) and subdivided them into bacterial meningitis (n = 112) and viral meningitis (n = 236). CSF NLR was significantly higher in bacterial meningitis than in viral meningitis (P < 0.001), and its level was higher in Gram-negative bacterial infections than in Gram-positive bacterial infections (P = 0.01). In the receiver operating characteristic curve analysis, CSF NLR was better than CSF protein/sugar/WBC in the ability to distinguish bacterial meningitis from viral meningitis (AUC 0.91 ± 0.02 versus 0.88 ± 0.03/0.87 ± 0.03/0.86 ± 0.03), and using a cutoff point of 0.68, the sensitivity was 0.90, and the specificity was 0.75. Compared with Gram-positive infection, CSF NLR with Gram-negative infection was higher (media, IQR (1.18 (0.19-2.33) versus 3.90 (1.50-8.91), P = 0.01).

Conclusion: CSF NLR is a more useful diagnostic tool to distinguish between bacterial meningitis and viral meningitis in children. While at a cutoff value of 0.68, CSF NLR has better sensitivity and specificity for bacterial meningitis, and the higher level of CSF NLR could be related to Gram-negative bacterial infection.