The Role Of NLR And Lactate In The Differential Diagnosis Between Pediatric Bacterial Meningitis And Viral Meningoencephalitis

ObjectiveThis study is to evaluate the role of neutrophil-to—lymphocyte ratio(NLR)and lactate in the differential diagnosis between bacterial meningitis and Viral meningoencephalitis.The routine laboratory parameters of the two groups,such as blood routine examination、CRP、the routine test and biochemistry indicators of CSF,were detected at the same time to observe their difference between bacterial meningitis and Viral meningoencephalitis groups to assist the identification.Methods89 bacterial meningitis and 164 viral meningoencephalitis patients in Shandong Qilu Hospital from January 2014 to June 2016 were enrolled in the study according to inclusion and exclusion criteria strictly.NLR and CSF lactate in cerebrospinal fluid and serum were measured in three groups:patients with bacterial meningitis,viral meningoencephalitis and children with febrile convulsion.All the cases performed lumbar puncture and vein puncture within 24-72 hours after admitting.Cerebrospinal fluid(CSF)and peripheral blood were collected before blood routine examination,CSF lactate,CSF cytology and the traditional markers of CSF(protein,glucose and culture)were measured.The following was the analysis of CSF-LA,NLR and the traditional markers of the two groups.The cut-off value,sensitivity,specificity and classification accuracy of NLR,lactate and routine parameters(serum CRP,CSF protein,glucose and neutrophil count)were studied by receiver operating characteristic(ROC)curves.Results1.A total of 253 children aged 29days-16years,were included in the study—89 cases with bacterial meningitis,164 cases with viral meningoencephalitis and 50 cases as controls.50 in bacterial meningitis group were male children and 39 were female children.with an average age of 20.2 months.In the viral meningoencephalitis group,100 patients were male and 64 were female,and their average age was 77.4 months.The sex was similar in both groups(P=0.458>0.05),while the age of the two groups had significant differences(P=0.001).80.1%of bacterial meningitis were infants and children younger than two years old.2.The NLR levels in CSF in bacterial and viral central nervous system infection group were 8.2±12.85 and 0.43±1.02 respectively.The level was higher in bacterial meningitis than that in viral meningoencephalitis(t=5.525,P<0.001).The area under the curve(AUC)for the diagnosis of bacterial meningitis was 0.912(95%CI,0.873-0.951).The optimal NLR cut-off value in CSF was 0.42 with 0.93 sensitivity and 0.8 specificity.3.The NLR levels in blood of in bacterial and viral central nervous system infection groups were 4.08±3.55 and 2.27±3.55 respectively.The level was higher in bacterial meningitis than that in viral meningoencephalitis(t=6.566,P=0.011).The area under the curve(AUC)for the diagnosis of bacterial meningitis was 0.7(95%CI,0.623-0.778).The optimal NLR cut-off value in blood was 2.75 with sensitivity 0.514 and 0.833 specificity.4.The CSF lactate level in bacterial meningitis group was 4.24±2.83mmol/L.The level was obviously higher than that in both viral central nervous system infection group(1.83±0.51mmol/L)and control group(1.74±0.51mmol/L)(P<0.001;P(0.001).Higher CSF lactate level in bacterial meningitis was found on admission and showed a decrease after treatment.The area under the curve(AUC)for the diagnosis of bacterial meningitis was 0.826(95%CI,0.748-0.905).The optimal lactate cut-off value in CSF was 2.85mmol/L with sensitivity 0.7 and 0,967 specificity.5.There was no significant difference in NLR of bacterial central nervous system infection group between different sex.The NLR level in CSF in bacterial meningitis with acute complications was similar to those without complications(P=0.891>0.05).6.The sensitivity of the combined detection of NLR and lactate in CSF was 0.952 and the specificity was 0.912.Conclusions1.As a new inflammatory indicator,NLR plays an important role in the identification of bacterial and viral central nervous system infection.NLR is a simple and efficient detection method with low cost.2.NLR is a reliable predictor for early diagnosis of bacterial meningitis,whose optimal cut-off values were 0.48 in CSF and 2.75 in blood.There are higher sensitivity and specificity in CSF NLR than blood NLR for differential diagnosis between bacterial and viral central nervous system infection.3.There is higher CSF Lactate in bacterial meningitis than viral meningoencephalitis.It was considered a good biomarker for differentiating bacterial and viral central nervous system infection at a cut-off of 2.85mmol/L,while the sensitivity is low.Therefore,CSF lactate can not be used as a simple marker todiscriminate different central nervous system infection.4.The combination of NLR and lactate in CSF can further improve the sensitivity.Therefore it is a potential method for differentiation between bacterial meningitis and viral meningoencephalitis.5.Detecting CRP and the traditional markers of CSF(protein and glucose)of the two groups at the same time can facilitate the differenciation.