title: False positivity of the Aspergillus galactomannan Platelia ELISA because of piperacillin/tazobactam treatment: does it represent a clinical problem?
abstract: OBJECTIVE
  False-positive results of the galactomannan (GM) ELISA caused by concurrent administration of piperacillin/tazobactam have been reported in patients with febrile neutropenia.
  
  
  METHODS
  This prospective study investigated different sampling times in 30 patients receiving piperacillin/tazobactam for febrile neutropenia.
  
  
  RESULTS
  Prior to the first piperacillin/tazobactam infusion, a median GM index of 0.2 [interquartile range (IQR) 0.1-0.3] was noted; in two patients (7%) the index was 0.5. Immediately after piperacillin/tazobactam infusion, the median index increased to 0.3 (IQR 0.2-0.4, P = 0.002) leading to 21% (7/30) false-positive results, if > or = 0.5 is assumed as the cut-off level. GM indices before the next piperacillin/tazobactam infusion were not increased (median 0.2, IQR 0.2-0.35, P > 0.05), but 10% (3/30) were still > or = 0.5. With a cut-off level of > 0.7, no false-positive results were noted at any sampling time point.
  
  
  CONCLUSIONS
  We conclude that the clinical relevance of false-positive GM results during piperacillin/tazobactam treatment is small if samples are collected prior to infusion and if a cut-off level of > 0.7 is used.
authors.affiliation: Department of Internal Medicine III, University of Bonn, Bonn, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Orlopp
authors.forename: M
authors.initials: M
authors.lastname: von Lilienfeld-Toal
authors.forename: G
authors.initials: G
authors.lastname: Marklein
authors.forename: S M
authors.initials: SM
authors.lastname: Reiffert
authors.forename: A
authors.initials: A
authors.lastname: Welter
authors.forename: C
authors.initials: C
authors.lastname: Hahn-Ast
authors.forename: I
authors.initials: I
authors.lastname: Purr
authors.forename: M
authors.initials: M
authors.lastname: Gorschlüter
authors.forename: E
authors.initials: E
authors.lastname: Molitor
authors.forename: A
authors.initials: A
authors.lastname: Glasmacher
mesh_terms: D000368:Aged; D000946:Antigens, Fungal / Q000097:blood; D001228:Aspergillosis / Q000175:diagnosis*; D001230:Aspergillus / Q000737:chemistry / Q000302:isolation & purification*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005189:False Positive Reactions; D005690:Galactose / Q000031:analogs & derivatives; D006801:Humans; D008351:Mannans / Q000097:blood*; D008875:Middle Aged; D010397:Penicillanic Acid / Q000031:analogs & derivatives* / Q000627:therapeutic use; D010878:Piperacillin / Q000627:therapeutic use*; D011446:Prospective Studies; D000078142:Tazobactam
chemical_list: D000946:Antigens, Fungal; D008351:Mannans; C012990:galactomannan; D010397:Penicillanic Acid; D000078142:Tazobactam; D010878:Piperacillin; D005690:Galactose