title: Ascitic fluid lactoferrin for diagnosis of spontaneous bacterial peritonitis.
abstract: OBJECTIVE
  The diagnosis of spontaneous bacterial peritonitis (SBP) is based on a manual count of ascitic fluid polymorphonuclear cells (PMNs). This procedure is operator-dependent and lysis of PMNs during transport to the laboratory may lead to false-negative results. Furthermore, ascitic fluid culture is insensitive and leads to delays in diagnosis. The aim of this study was to assess the utility of ascitic fluid lactoferrin (AFLAC) for the diagnosis of SBP and to identify a cut-off level that can be used for future development of a rapid bedside test.
  
  
  METHODS
  A total of 218 consecutive ascites samples from 148 patients (1-8 samples per patient) with cirrhosis at 2 tertiary care medical centers were examined for PMN count, bedside culture, and lactoferrin concentration. AFLAC concentrations were determined using a polyclonal antibody-based enzyme-linked immunosorbent assay. An ascitic fluid PMN count of 250 cells/mL or greater with or without a positive culture was used for diagnosis of SBP.
  
  
  RESULTS
  Twenty-two (10.1%) samples fulfilled diagnostic criteria for SBP. Samples with SBP had a significantly higher lactoferrin concentration (median, 3744 ng/mL; 25th-75th percentiles [P25-P75], 788-9617) compared with non-SBP samples (median, 31 ng/mL; P25-P75, 12-67; P < .001). By using a cut-off level of 242 ng/mL, the sensitivity and specificity of the assay for diagnosis of SBP were 95.5% and 97%, respectively. The area under the receiver operating characteristic curve was 0.98.
  
  
  CONCLUSIONS
  AFLAC can serve as a sensitive and specific test for diagnosis of SBP. Qualitative bedside assays for the measurement of AFLAC can be developed easily and may serve as a rapid and reliable screening tool for SBP in patients with cirrhosis.
authors.affiliation: Digestive Disease Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA. parsim@ccf.org
authors.forename: Mansour A
authors.initials: MA
authors.lastname: Parsi
authors.forename: Sherif N
authors.initials: SN
authors.lastname: Saadeh
authors.forename: Nizar N
authors.initials: NN
authors.lastname: Zein
authors.forename: Gary L
authors.initials: GL
authors.lastname: Davis
authors.forename: Rocio
authors.initials: R
authors.lastname: Lopez
authors.forename: James
authors.initials: J
authors.lastname: Boone
authors.forename: Maria R
authors.initials: MR
authors.lastname: Lepe
authors.forename: Linsheng
authors.initials: L
authors.lastname: Guo
authors.forename: Mohammad
authors.initials: M
authors.lastname: Ashfaq
authors.forename: Goran
authors.initials: G
authors.lastname: Klintmalm
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: McCullough
mesh_terms: D001202:Ascitic Fluid / Q000737:chemistry* / Q000166:cytology; D001424:Bacterial Infections / Q000150:complications / Q000175:diagnosis*; D015415:Biomarkers / Q000032:analysis; D006801:Humans; D007781:Lactoferrin / Q000032:analysis*; D007958:Leukocyte Count; D008103:Liver Cirrhosis / Q000150:complications; D009504:Neutrophils; D010538:Peritonitis / Q000150:complications / Q000175:diagnosis*; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D007781:Lactoferrin