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Journal of Clinical Microbiology, September 2007, p. 3141-3142, Vol. 45, No. 9
0095-1137/07/$08.00+0 doi:10.1128/JCM.00974-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
Intravenous PLASMA-LYTE as a Major Cause of False-Positive Results of Platelia Aspergillus Test for Galactomannan Detection in Serum
Zdenek Racil
Iva Kocmanova
Martina Lengerova
Jana Winterova
Jiri Mayer*
Department of Internal Medicine-Hemato-Oncology
University Hospital
Brno 625 00
Czech Republic
Department of Microbiology
University Hospital
Brno 625 00
Czech Republic
Center of Molecular Biology and Gene Therapy
Department of Internal Medicine-Hemato-Oncology
University Hospital
Brno 625 00
Czech Republic
Department of Internal Medicine-Hemato-Oncology
University Hospital
Brno 625 00
Czech Republic
Department of Internal Medicine-Hemato-Oncology
University Hospital
Brno 625 00
Czech Republic
Received 10 May 2007/
Returned for modification 17 July 2007/
Accepted 20 July 2007

INTRODUCTION
Galactomannan (GM) detection by the Platelia
Aspergillus (PA)
enzyme immunoassay (Bio-Rad, France) is a test widely used for
the early diagnosis of invasive aspergillosis (IA) in hematooncological
patients. False-positive results for this test were reported
by several authors, associated mainly with the use of the beta-lactam
antibiotics piperacillin-tazobactam and amoxicillin-clavulanic
acid (
1,
4). Recently, the intravenous hydration fluid PLASMA-LYTE
(Baxter) was identified as the cause of false-positive results
with the PA test when it was used for bronchoalveolar lavage
(
3). However, regarding the serum concentration following intravenous
administration, the authors speculated that it would be below
the detection limit of the PA assay (due to dilution in the
intravascular compartment).
The PA test has been used in our department since May 2003 for regular screening (twice a week) of patients with hematological malignancy who are at risk for IA. Between January 2005 and March 2007, a total of 1,137 patients were tested with the PA assay, and 172 of them had more than two positive blood samples (optical density index above 0.5 within 7 days). Fifty-five (32%) positive patients had proven or probable IA, according to the European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria (2). For 117 (68%) patients, the test results were finally assessed as false positives. A gradual increase in the number of false-positive results among patients tested for GM in sera was observed during the year 2006 and at the beginning of 2007. False positivity due to the use of beta-lactam antibiotics was excluded, as all batches of piperacillin-tazobactam and amoxicillin-clavulanic acid used at our department have been tested for the presence of GM since July 2005. Only negative batches (PA assay optical density index of <0.5) were administered to our patients.
After the report about the possible influence of PLASMA-LYTE on PA assay results had been published, we tested the four different batches of PLASMA-LYTE solution available at our institution. All of these were highly GM positive, with a mean optical density index of 7.73 (range, 7.15 to 8.53).
Therefore, we decided to perform a study with healthy volunteers to confirm our hypothesis that the intravenous administration of PLASMA-LYTE can also lead to false-positive results with the PA assay when serum is tested. Four lots (1,000 ml each) from two different batches were given to four healthy volunteers in 1-h infusions. Blood samples for GM detection using the PA test were obtained by separate venipunctures before administration, then immediately after the end of infusion, and then after 5, 7, 10, 24, and 34 h. In all healthy subjects, PLASMA-LYTE administration led to positive PA assay results that persisted for 24 h after infusion (Table 1).
The validation of PLASMA-LYTE as the cause of false positivity
in healthy volunteers made us reevaluate the clinical and medical
histories of all patients with false-positive results with the
PA test in order to trace the possible source of GM contamination.
When we focused on PLASMA-LYTE, which has been used in our hematooncological
department since October 2004, we found that the administration
of this solution could account for 80% of false-positive results
with the PA test for our patients tested between January 2005
and March 2007 and, more precisely, 90% of those for patients
given only negative batches of beta-lactam antibiotics (July
2005 to March 2007). Moreover, an increase in the number of
false-positive results correlated well with the increased consumption
of the PLASMA-LYTE solution. Data concerning false and true
PA test positivity, the cause of false positivity, and PLASMA-LYTE
consumption are summarized in Fig.
1.
To the best of our knowledge, this is the first report of false-positive
results with the PA test, using PLASMA-LYTE as an intravenous
hydration and testing the serum used. PLASMA-LYTE solution has
been retrospectively identified as the most probable cause of
a false-positive result with the PA assay in over 80% of samples
from patients without clinical evidence of invasive aspergillosis.
This observation has also been confirmed with healthy volunteers.
Our findings are very important for routine practice, and such
information could avoid the unnecessary preemptive use of mold-active
antifungal drugs.

ACKNOWLEDGMENTS
This work was supported by a research grant from the Ministry
of Health, Czech Republic, IGA NR 8452-3/2005, and partly by
CELL, the
Cz
ech
Leukemia Study Group for
Life.

FOOTNOTES
* Phone: 420532233642, Fax: 420532233603, E-mail:
jmayer{at}fnbrno.cz 
Published ahead of print on 1 August 2007. 

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Journal of Clinical Microbiology, September 2007, p. 3141-3142, Vol. 45, No. 9
0095-1137/07/$08.00+0 doi:10.1128/JCM.00974-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.