title: False positivity for Aspergillus antigenemia related to the administration of piperacillin/tazobactam.
abstract: BACKGROUND
  Invasive aspergillosis is a challenge to the internist, and difficulties diagnosing the disease remain an everlasting problem.
  
  
  METHODS
  We reviewed the data of 65 patients with hematological malignancies and aplastic anemia who were tested for the galactomannan (GM) antigen of Aspergillus between March and November 2003.
  
  
  RESULTS
  GM antigen levels were false-positive in at least two consecutive samples in 5 out of 23 patients who did not have evidence of invasive aspergillosis (false positivity rate of 21.7%) but who received concomitant piperacillin/tazobactam (P/T) compared to 0 of 28 patients who did not.
  
  
  CONCLUSIONS
  The use of P/T in febrile, neutropenic patients decreases the specificity of GM antigen testing, which may lead to incorrect and unnecessary attempts at diagnosis and therapy.
authors.affiliation: Department of Internal Medicine, Hacettepe University School of Medicine, 06100, Sihhiye, Ankara, Turkey. mdurusu@hacettepe.edu.tr
authors.forename: Mine Durusu
authors.initials: MD
authors.lastname: Tanriover
authors.forename: Gökhan
authors.initials: G
authors.lastname: Metan
authors.forename: Belgin
authors.initials: B
authors.lastname: Altun
authors.forename: Gulsen
authors.initials: G
authors.lastname: Hascelik
authors.forename: Omrum
authors.initials: O
authors.lastname: Uzun