title: The usefulness of serum delta neutrophil index for differentiating bacterial and viral meningitis in the emergency department.
abstract: OBJECTIVE
  When managing patients with acute meningitis in an emergency department (ED), early diagnosis of the type of infection (bacterial or viral) considerably affects the clinical course and treatment because of the high mortality and morbidity associated with bacterial meningitis (BM). The serum delta neutrophil index (DNI), a new inflammatory marker, reflects the fraction of circulating immature granulocytes and is elevated in cases of bacterial infection. The objective of this study was to evaluate whether serum DNI can be used to differentiate between BM and viral meningitis (VM) in the ED.
  
  
  METHODS
  This retrospective, observational study included 104 consecutive patients (aged >18 years) diagnosed with acute meningitis from January 2012 to November 2014 in a regional emergency center. White blood cell and neutrophil counts, C-reactive protein level, and DNI were evaluated regarding their usefulness for differentiating BM and VM.
  
  
  RESULTS
  Serum DNI was not significantly higher in the BM group (n=12) than in the VM group (n=92) (0 [interquartile range, 0% to 2.73%] vs. 0 [interquartile range, 0 to 0%], P=0.057). However, the white blood cell count and C-reactive protein level were statistically higher in the BM group (P=0.034 and P=0.026, respectively). Serum DNI was not found to be a statistically useful differential diagnostic parameter (area under the curve, 0.628; 95% confidence interval, 0.438 to 0.818).
  
  
  CONCLUSIONS
  Currently, there is no evidence that the serum DNI aids in differentiating acute BM from acute VM in the ED.
authors.affiliation: Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Joon Woo
authors.initials: JW
authors.lastname: Lee
authors.affiliation: Department of Neurology, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Chan Ik
authors.initials: CI
authors.lastname: Park
authors.affiliation: Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Hyung Il
authors.initials: HI
authors.lastname: Kim
authors.affiliation: Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Oh Hyun
authors.initials: OH
authors.lastname: Kim
authors.affiliation: Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Kyoung Chul
authors.initials: KC
authors.lastname: Cha
authors.affiliation: Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Hyun
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Kang Hyun
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Sung Oh
authors.initials: SO
authors.lastname: Hwang
authors.affiliation: Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Yong Sung
authors.initials: YS
authors.lastname: Cha
keywords: Biochemical markers; Delta neutrophil index; Meningitis