Significance of cerebrospinal fluid lactate level in diagnosing neonatal bacterial meningitis

Abstract

Objective To study the significance of the cerebrospinal fluid (CSF)lactate level in diagnosing neonatal bacterial meningitis(BM). Methods The CSF samples were collected from neonates admitted to Neonatal Ward of Children's Hospital of Fudan University between January 2014 and March 2015.CSF lactate and glucose concentrations were measured with blood-gas analyzer.CSF and serum glucose levels were measured with glucometer.The enrolled neonates were divided into 2 groups based on CSF culture, CSF white blood cells(WBCs)and clinical presentation: observation group (neonates with BM)and control group (neonates without BM). Statistical analysis of data was performed with Stata 12.0. Results A total of 93 infants (16 assigned to observation group and 77 assigned to control group)met the inclusion criteria.Neonates in observation group had higher median CSF lactate level (4.2 mmol/L)and CSF lactate/glucose ratio (L/Gcsf)(2.32 mmol/L), than those in control group (1.3 mmol/L, 0.52), and there were significant differences (Z=-6.19, -5.92, all P<0.05). CSF glucose levels were lower in observation group (me-dian, 1.25 mmol/L)than those in control group (median, 2.5 mmol/L), and the difference was significant(Z=4.97, P<0.05); CSF/serum glucose ratio (CSF/Sglu)were lower in observation group (median, 0.44 vs 0.81 in control group), and the difference was significant(Z=4.43, P<0.05). The optimal CSF lactate cutoff point of 2.2 mmol/L had a positive predictive value (PPV)of 72.7% and negative predictive value (NPV)of 100.0% for bacterial meningitis.The optimal L/Gcsf cutoff point of 1.24 had a PPV of 94.1% and NPV of 100.0%.The optimal CSF glucose cutoff point of 2.0 mmol/L had a PPV of 65.0% and NPV of 95.9%.The optimal CSF/Sglu cutoff point of 0.6 had a PPV of 60.0% and a NPV of 96.9%. Conclusion CSF lactate may be an excellent biomarker for early diagnosis of neonatal BM. Key words: Bacterial meningitis; Cerebrospinal fluid lactate; Cerebrospinal fluid/serum glucose ratio