title: Quantitation of cerebrospinal fluid lactic acid in infectious and non-infectious neurological diseases.
abstract: BACKGROUND
  The differential diagnosis between bacterial and viral meningitis is not easy in some cases. Cerebrospinal fluid (CSF) analysis is essential for establishing this diagnosis. The objectives were to quantitate lactic acid (LA) concentrations in bacterial and viral meningitis, and other central nervous system (CNS) diseases in order to evaluate the diagnostic utility of CSF LA for discriminating bacterial from viral meningitis.
  
  
  METHODS
  CSF LA was measured in 139 CSF samples from seven groups: viral meningitis with classic CSF; suspicion of viral meningitis with neutrophils in CSF; bacterial meningitis; non-infectious neurological diseases; chronic meningitis; traumatic lumbar puncture (LP) and normal CSF.
  
  
  RESULTS
  CSF LA was higher in bacterial meningitis 8.7 + 5.4 mmol/L compared with viral meningitis (1.9 + 0.6) and the other groups (p < 0.0001). CSF LA in the groups with viral meningitis was not different compared to groups with non-infectious CNS diseases and chronic meningitis. The ability of CSF LA to discriminate bacterial from viral meningitis showed a sensitivity of 80% and specificity of 97%, positive predictive value (PPV) of 94%, and negative predictive value (NPV) of 89%.
  
  
  CONCLUSIONS
  CSF LA is a powerful test to discriminate bacterial from viral meningitis with high sensitivity, specificity and predictive values. CSF LA can help in the cases with diagnostic uncertainty.
authors.affiliation: Virology Section, Clinical Pathology Laboratory, Hospital de Clínicas, Federal University of Paraná, Curitiba, PR, Brazil. sergio.ma@pop.com.br
authors.forename: Sérgio Monteiro
authors.initials: SM
authors.lastname: de Almeida
authors.forename: Fernanda Luize
authors.initials: FL
authors.lastname: Faria
authors.forename: Karina
authors.initials: K
authors.lastname: de Goes Fontes
authors.forename: Gisele Maria
authors.initials: GM
authors.lastname: Buczenko
authors.forename: Denize Bonato
authors.initials: DB
authors.lastname: Berto
authors.forename: Sonia Mara
authors.initials: SM
authors.lastname: Raboni
authors.forename: Luine Rosele
authors.initials: LR
authors.lastname: Vidal
authors.forename: Meri Bordignon
authors.initials: MB
authors.lastname: Nogueira
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000134:cerebrospinal fluid; D002555:Cerebrospinal Fluid / Q000737:chemistry / Q000166:cytology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000134:cerebrospinal fluid*; D007958:Leukocyte Count; D008137:Longitudinal Studies; D008297:Male; D016920:Meningitis, Bacterial / Q000134:cerebrospinal fluid / Q000382:microbiology; D008587:Meningitis, Viral / Q000134:cerebrospinal fluid / Q000821:virology; D009422:Nervous System Diseases / Q000134:cerebrospinal fluid* / Q000382:microbiology / Q000821:virology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D015415:Biomarkers; D019344:Lactic Acid