Cerebrospinal Fluid Lactate as an Indicator for Post-Neurosurgical Bacterial Meningitis

Objective: To evaluate the interest of cerebrospinal fluid (CSF) lactate assay for the diagnosis of post-neurosurgical bacterial meningitis (PBM). Methods: We conducted at our neurosurgical resuscitation unit a prospective study of patients who underwent elective or emergency craniotomy. Lumbar puncture was performed in all patients who had clinical suspicion of PBM for CSF culture and cytological and chemical analysis (glucose, protein, lactate). The diagnosis of PBM is made according to the criteria proposed by the Center for Disease Control and Prevention (CDC). Receiver Operating Characteristic (ROC) was used to determine the diagnostic accuracy of CSF lactate. Results: 72 patients were studied and only 32 of them had the clinical and biological criteria of the diagnosis of PBM. Median CSF lactate was 6.18 mmol/L for PBM versus 2.63 mmol/L for no PBM (p < 0.001). CSF lactate may predict the presence PBM, with a AUC of 0.98 and NPV of 99.1. The analysis of Youden's index also confirms the good diagnostic power of CSF lactate, with a value of 83 at a cut-off value of 4 mmol/L, with a sensitivity of 92.3 and specificity of 91.6%. Conclusion: Our study shows that the CSF lactate as an indicator for PBM. It is a fast and simple test that can help the clinician to optimize the management of PBM and decrease premature cessation of antibiotics.