title: A new highly sensitive point of care screen for spontaneous bacterial peritonitis using the leukocyte esterase method.
abstract: OBJECTIVE
  Urine reagent strips measuring leukocyte esterase activity have been studied to screen spontaneous bacterial peritonitis (SBP) but are insensitive. We calibrated a strip specifically for ascitic fluid to achieve high sensitivity in this diagnosis.
  
  
  METHODS
  Experiments were conducted on ascitic fluid from patients with cirrhosis. Samples with SBP were diluted with native acellular ascitic fluid to achieve PMN counts below, above, and close to the diagnostic threshold of 250 PMN/microl. A model of SBP was created by spiking negative ascitic fluid samples (<250 PMN/microl) with activated PMN from blood of patients with sepsis, and diluted to achieve a range of PMN. Aliquots were tested at 2, 3, 4, and 10 min with the Periscreen leukocyte esterase strip. PMN/microl was correlated to timings and color scales: white defined negative (PMN <250/microl); and shades of brown, purple, and pink defined positive. Ascitic fluid samples were obtained from 58 patients. Negative ascitic fluid was used from 32 to generate the model SBP.
  
  
  RESULTS
  One thousand three hundred and four experiments were performed with a median PMN count of 492/microl (0-7510). After exclusion of uninterpretable colorimetric results, 1089 experiments were analyzed [PMN of 444/microl (0-7510)]. The best result was obtained at 3 min (n=299), with Se: 100%, Sp: 57.9%; NPV: 100%, PPV: 76.5%. The test was not interpretable in bloody, chylous or bilious ascitic fluid, or concurrent imipenem treatment.
  
  
  CONCLUSIONS
  This new leukocyte esterase strip calibrated to an ascitic fluid PMN count 250/microl is a robust screening tool when the strip turns any hue of tan/brown at 3 min.
authors.affiliation: Loma Linda University Medical Center, Department of Medicine, Division of GI and Liver Diseases, Loma Linda, CA 92354, USA. mmendler@llu.edu
authors.forename: Michel Henry
authors.initials: MH
authors.lastname: Mendler
authors.forename: Arun
authors.initials: A
authors.lastname: Agarwal
authors.forename: Mateen
authors.initials: M
authors.lastname: Trimzi
authors.forename: Erika
authors.initials: E
authors.lastname: Madrigal
authors.forename: Matthew
authors.initials: M
authors.lastname: Tsushima
authors.forename: Elliot
authors.initials: E
authors.lastname: Joo
authors.forename: Marisela
authors.initials: M
authors.lastname: Santiago
authors.forename: Elissa
authors.initials: E
authors.lastname: Flores
authors.forename: Gabriel
authors.initials: G
authors.lastname: David
authors.forename: Adrienne
authors.initials: A
authors.lastname: Workman
authors.forename: Bruce
authors.initials: B
authors.lastname: Runyon
mesh_terms: D001202:Ascitic Fluid / Q000201:enzymology*; D001424:Bacterial Infections / Q000175:diagnosis* / Q000201:enzymology* / Q000209:etiology; D002265:Carboxylic Ester Hydrolases / Q000032:analysis*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D006975:Hypertension, Portal / Q000150:complications; D008103:Liver Cirrhosis / Q000150:complications; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000201:enzymology; D010538:Peritonitis / Q000175:diagnosis* / Q000201:enzymology* / Q000209:etiology; D019095:Point-of-Care Systems / Q000706:statistics & numerical data; D011934:Reagent Strips; D012680:Sensitivity and Specificity
chemical_list: D011934:Reagent Strips; C021443:leukocyte esterase; D002265:Carboxylic Ester Hydrolases