Comparison of a novel Aspergillus antigen lateral flow device with the Platelia Aspergillus Antigen ELISA in patients after haematopoietic stem cell transplantation

Ref ID: 19230

Author:

J. Held*, T. Schmidt, E. Kotter, C. Thornton, H. Bertz

Author address:

Freiburg, DE; Exeter, GB

Full conference title:

23rd European Congress of Clinical Microbiology and
Infectious Diseases

Date: 27 April 2014

Abstract:

Objectives: One cornerstone for diagnosis of Invasive aspergillosis (IA) is the detection of antigens in serum. A widely used test for this purpose is the Platelia-ELISA. Limitations of this assay are the turn-around time of 3 hours and the need for a fully equipped laboratory. As a consequence in some diagnostic labs the ELISA is performed only once a week or not at all. A novel test that might overcome these limitations is the Aspergillus Lateral-Flow Device (LFD). The LFD is an immunochromatographic assay that detects an extracellular glycoprotein secreted during growth of Aspergillus fumigatus in serum or BAL fluid. It is designed as a fast (15 min) point-of-care test that can be performed without extensive laboratory equipment. Recent studies in animal models have shown promising results. However, studies examining human serum samples are lacking. Therefore we have conducted a retrospective study in patients after hematopoietic stem cell transplantation (HSCT) to compare the diagnostic performance of the LFD and the Platelia-ELISA.
Methods: All patients that underwent HSCT at the University Hospital Freiburg during 2010 were enrolled. Patients with IA were classified according to the EORTC/MSG 2008 guidelines. A threshold of 0.5 ODI was used for Platelia-ELISA positivity. The results of the LFD were read independently by three laboratory assistants in a blinded fashion. Serum from a healthy person served as a cut-off control.
Results: A total of 596 sera from 101 patients after HSCT were tested. By the end of hospitalization 1 proven, 7 probable and 18 possible IA cases were diagnosed. The sensitivity, specificity, positive and negative likelihood ratio for proven and probable IA were as follows: LFD: 37.5 % (95%-CI: 10.2-74.1), 88.0 % (95%-CI: 78.0-94.0), 3.13 and 0.71. Platelia-ELISA: 37.5 % (95%-CI: 10.2-74.1), 89.3 % (95%-CI: 79.5-95.0), 3.52 and 0.70. The only proven IA was detected by the Platelia-ELISA but not by the LFD. Sera with Platelia-ELISA ODIs below 1.0 were never positive in the LFD.
Conclusion: The novel LFD and the Platelia-ELISA show an almost identical diagnostic performance per patient. Therefore, the LFD is a valuable alternative especially in places where the Platelia-ELISA is not performed on a daily basis.
Handling of the LFD is easy. However, reading the test is challenging because of a faint, unspecific band appearing in a large number of sera. We therefore highly recommend using serum from a healthy person as a cut-off control.

Abstract Number: P1737

Conference Year: 2013

Link to conference website: http://registration.akm.ch/einsicht.php?XNABSTRACT_ID=167381&XNSPRACHE_ID=2&XNKONGRESS_ID=180&XNMASK

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