Diagnostic value of cerebrospinal fluid lactic acid in bacterial meningitis after craniotomy for cerebral hemorrhage in adults

Objective To explore the diagnostic value of cerebrospinal fluid (CSF) lactic acid (LA) level in bacterial meningitis after craniotomy for cerebral hemorrhage in adults. Methods The clinical data of 162 patients with cerebral hemorrhage, admitted to and accepted craniotomy in our hospital from April 2013 to April 2018, were retrospectively collected; patients were divided into infected group (n=75) and non-infected group (n=87) according to whether postoperative bacterial meningitis occurred; univariate analysis was used to compare the differences of CSF-LA concentration and other indicators of CSF between patients of the two groups; multivariate Logistic regression analysis was used to screen the independent factors affecting the occurrence of postoperative bacterial meningitis; receiver operating characteristic (ROC) curve was used to analyze the predictive values of CSF-LA and other indicators in postoperative bacterial meningitis. Furthermore, 17 patients with positive bacterial CSF were divided into Gram-positive (G+) bacteria group (n=9) and Gram-negative (G-) bacteria group (n=8); the predictive values of CSF-LA and other indicators for postoperative meningitis of G- bacteria patients were analyzed in the same way. Results (1) The CSF-LA concentration in infected group([6.3±2.8] mmol/L) was significantly increased as compared with that in non-infected group ([3.3±1.6] mmol/L, P<0.05); the results of multivariate Logistic regression analysis showed that CSF-LA was an independent influencing factor for postoperative bacterial meningitis (odd ratio=1.547, 95% confidence interval: 1.029-2.326, P=0.036); ROC curve results revealed that the area under the curve of CSF-LA concentration in the diagnosis of bacterial meningitis after craniotomy was 0.854 (95% confidence interval: 0.790-0.904), and the optimal cut-off value was 4.61 mmol/L, with sensitivity of 69.3%, specificity of 92.0%, positive predictive value of 88.1% and negative predictive value of 77.7%. (2) The CSF-LA concentration in G- bacteria group ([9.9±2.9] mmol/L) was significantly increased as compared with that in G+ bacteria group ([5.2±3.1] mmol/L, P< 0.05); ROC curve results revealed that, in patients with positive bacterial CSF, the area under the curve of CSF-LA concentration in diagnosis of meningitis with G- bacteria after craniotomy was 0.861 (95% confidence interval: 0.610-0.978), and the optimal cut-off value was 7.20 mmol/L with sensitivity of 87.5%, specificity of 88.9%, positive predictive value of 87.5%, and negative predictive value of 88.9%. Conclusion Detection for concentration of CSF-LA can help predicting bacterial meningitis after craniotomy for cerebral hemorrhage and identify G+ and G- bacteria meningitis. Key words: Bacterial meningitis; Cerebral hemorrhage; Cerebrospinal fluid; Lactic acid; Craniotomy