False‐positive Candida and Aspergillus antigen testing in recipients of allogeneic haematopoietic cell transplantation due to administration of parenteral nutrition and fixed combinations of piperacillin‐tazobactam

Abstract

Summary False positivity of antigen immunoassays used as an early diagnostic tool to detect invasive fungal infections is known. Interpretation of the assay needs the identification of sources which could affect the specificity of the test. We focused on the influence of parenteral nutrition (PN) and piperacillin‐tazobactam (TZP) on fungal immunoassays. Measurable amounts of Candida antigen mannan were detected in several compounds of PN and TZP in a previous in vitro study. In the current study, 84 patients undergoing allogeneic haematopoietic cell transplantation receiving either TZP, PN or both were monitored with Aspergillus and Candida antigen assay. Six patients were analysed closer in a kinetic analysis with more frequent blood sampling to detect mannan. PN in diverse compositions as well as TZP did not increase significantly the amount of mannan and the Aspergillus antigen in serum. We could not confirm the positive results of the in vitro study. Physicians should be aware that mannan antigenemia due to drug infusion could be a transient issue and should be considered in the interpretation of fungal immunoassays, although we could not find clinically relevant effects on mannan levels.

Comparison of the Performance of Two Galactomannan Detection Tests: Platelia Aspergillus Ag and Aspergillus Galactomannan Ag Virclia Monotest

“…The Platelia Aspergillus Ag kit (Bio-Rad) was approved by the FDA in 2003 and detects the presence of GLM produced by Aspergillus during its invasive growth. The use of this test has been particularly beneficial in neutropenic patients and has been limited by the existence of false positives in patients exposed to products that may have been contaminated by fungal remains during manufacture; examples include certain antibiotics and even some bags used for collection and administration of platelets ( 26 , 27 ). Occasionally, patients with well-demonstrated bacterial diseases show positive GLM results, but it is often difficult to rule out the presence of coinfections in some of those cases detected by the tests ( 28 – 33 ).…”