New Aspergillus antigen detection LFD kit for the IPA diagnostic: What results with positive and negative galactomannan ELISA sera?

Ref ID: 19393

Author:

F. Persat

Author address:

Hospices Civils de Lyon, France

Full conference title:

6th Trends in Medical Mycology 2013

Date: 11 October 2014

Abstract:

Objectives Diagnosis of probable invasive pulmonary aspergillosis
(IPA) according to EORTC criteria relies, in part, on the detection of
ª 2013 The Authors
Mycoses © 2013 Blackwell Verlag GmbH, 56 (Suppl. 3), 55-167 85
Poster Presentations
Aspergillus galactomannan (GM) in patient’s sera. GM detection is
achieved by using the PlateliaTM Aspergillus ELISA BioRad, but the
test is constrained by false positive and false negative results. Alter-
native tests that detect surrogate markers of infection include the
newly developed Aspergillus lateral-flow device (LFD) that is currently
in the process of commercialization. Our objective was to evaluate
the prototype LFD as a diagnostic test for IPA and to compare it ret-
rospectively to the GM ELISA for detection of probable disease in dif-
ferent patient groups.
Methods Probable IPA was defined according to EORTC guidelines
(1), following analysis of clinical, radiological and biological parame-
ters. A total of 66 patients were considered: 38 hematology patients,
21 ICU patients and 7 patients from other settings (pneumology,
internal medicine”¦). Seventy two sera assayed by GM ELISA during
routine diagnostic testing have been selected: 18 GM positive and 18
GM negative for IPA patients, then considered as true positive and
false negative, respectively and 18 GM positive and 18 GM negative
for non-IPA patients, then considered as false positive and true nega-
tive, respectively. LFD testing of serum was performed retrospectively
in a blinded fashion and visual appraisals of test positivities were
conducted as described previously (2) by three independent apprais-
ers. Test samples were compared to known antigen positive and anti-
gen negative sera.
Results In patients identified with probable IPA according to EORTC
diagnostic guidelines, 22 serum samples out of 36 were concordant
by both GM ELISA and LFD (11 GM positive-LFD positive; 11 GM
negative-LFD negative). Among the 14 discordant results, seven
serum samples were detected by only GM ELISA and seven other by
only the LFD kit. In non-IPA patients, the LFD was considered posi-
tive for 2 out of the 36 samples tested, showing superior specificity
in these patients compared to the GM test (18 false positive, as cho-
sen for the study design). The LFD results was then significant in
these conditions for the IPA diagnostic (p < 0.05; chi2 test) and more particularly in hematology (p < 0.05; Fisher’s exact test). Conclusion The LFD allows simple and rapid (under 30 minutes) testing of serum samples with a similar sensitivity for IPA detection compared to the GM ELISA, but with higher specificity. Further test- ing is needed to validate our findings using the fully commercialized LFD kit but, if confirmed, our results show the usefulness of the LFD as a rapid front-line test for evaluating a patient’s IPA status. (1) De Pauw B. et al. Clin Infect Dis. (2008) 46: 1813-1821. (2) Thornton C.R. Clin Vaccin Immunol (2008) 15: 1095-1105.

Abstract Number: P077

Conference Year: 2013

Link to conference website: NULL

New link: NULL

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