Piperacillin/tazobactam (Tazocin™) seems to be no longer responsible for false-positive results of the galactomannan assay

M. Mikulska, E. Furfaro, V. Del Bono, A. M. Raiola, S. Ratto, A. Bacigalupo, C. Viscoli

Research output: Contribution to journalArticlepeer-review


Objectives: Galactomannan (GM) testing is extremely useful for diagnosing invasive aspergillosis in high-risk patients, but false-positive results have been reported in patients treated with piperacillin/tazobactam. The aims of this study are to test if the recent piperacillin/tazobactam (Tazocin™; Pfizer) preparation still contains GM, and if serum GM positivity in haematopoietic stem cell transplant (HSCT) recipients receiving piperacillin/tazobactam can be attributed to this treatment. Patients and methods: Serum samples obtained from 1 October 2009 to 31 October 2010 from HSCT recipients for GM testing were analysed. The difference in the rate of positive results (defined as GM ≥0.5) in patients receiving and not receiving piperacillin/tazobactam was evaluated. Piperacillin/tazobactam vials from randomly selected batches were tested. Results: Of 1606 samples drawn in the absence of piperacillin/tazobactam therapy, 25 (1.6%) tested positive for GM versus 10 of 394 samples (2.5%) drawn while on piperacillin/tazobactam (P = 0.18). The median GM result of samples drawn on piperacillin/tazobactam was slightly higher than that of samples drawn in the absence of piperacillin/tazobactam (0.141 versus 0.122; P <0.001). All 90 piperacillin/tazobactam vials from 30 randomly selected batches tested negative for GM, with a median GM value of 0.057 (range: 0.011-0.320). Conclusions: Although some residual GM might still be present in piperacillin/tazobactam, currently available brand piperacillin/tazobactam preparations seem no longer responsible for false-positive GM results.

Original languageEnglish
Article numberdks111
Pages (from-to)1746-1748
Number of pages3
JournalJournal of Antimicrobial Chemotherapy
Issue number7
Publication statusPublished - Jul 2012


  • False positivity
  • Fungal infection
  • Platelia Aspergillus

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases

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