Evaluation of the performance of the Dynamiker Fungus (1-3)-β-D-glucan assay for the diagnosis of invasive aspergillosis in high-risk patients with haematological malignancies

Maria Siopi *1, Maruša Krmelj 1, Stamatis Karakatsanis 2, Christoforos Roumpakis 3, Elina Eldeik 4, Konstantinos Korantanis 5, Helen Sambatakou 4, Panagiotis Tsirigotis 3, Maria Pagoni 2, Nikolaos Sypsas 5, Spyros Pournaras 1, Joseph Meletiadis 1;6

Author address: 

1 Clinical Microbiology Laboratory, “Attikon” University General Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece; 2 Department of Hematology and Lymphoma, Unit of Bone Marrow Transplantation, “Evangelismos” General Hospital, Athens, Greece; 3 2nd Department of Internal Medicine, Hematology Unit, “Attikon” University General Hospital, National and Kapodistrian University of Athens Medical School, Athens, Greece; 4 2nd Department of Internal Medicine, “Hippokration” General Hospital, Athens, Greece; 5 Pathophysiology Department, Medical School, National and Kapodistrian University of Athens, Athens, Greece; 6 Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, Netherlands

Abstract: 

Background: Non-culture-based methods, like detection of circulating galactomannan (GM) and (1-3)-β-D-glucan (BDG), are important adjunctive diagnostic tools for invasive aspergillosis (IA). Until recently, only the Fungitell® assay (Associates of Cape Cod) has been commercially available (CE marking and FDA approval) for BDG testing. This changed with the release of the Dynamiker® Fungus BDG assay (CE marking), which contains detachable microplate rows allowing the test to be performed on a few clinical samples. We therefore evaluated the performance of the Dynamiker® Fungus assay in serum of high-risk haematological patients for the diagnosis of IA providing comparative data with the Fungitell® assay.

Materials/methods: During 4/2013-7/2015, a total of 173 serial blood specimens from 62 patients with haematological malignancies (35 AML, 9 ALL, 2 MDS, 2 NHL, 14 other) were collected twice-weekly and tested for GM (Platelia Aspergillus EIA) and BDG (Fungitell®/Dynamiker®). 19/62 (31%) patients had probable IA and received voriconazole, while 43 had no IA according to the EORTC/MSG criteria. The BDG assays were performed following the manufacturer’s instructions and the samples were considered positive, indeterminate/inconclusive or negative based on the BDG levels of <60, 60-79, ≥80 pg/mL (Fungitell®) and <70, 70-95, >95 pg/mL (Dynamiker®), respectively. The BDG values generated by the two assays were compared quantitatively (Spearman analysis) and qualitatively (3x3 x2 analysis). Sensitivity/specificity rates and positive/negative predictive values (PPV/NPV) were calculated for each BDG assay.

Results: The mean absolute and relative difference between the BDG values of the assays tested was 50 pg/mL and 14%, respectively. BDG concentrations generated by the two assays were linearly correlated (slope 0.65±0.03, r2 =0.73) with high degree of correlation (Spearman rs (95%CI)=0.91 (0.88-0.94), p<0.0001). Sensitivity, specificity, PPV and NPV was 73%, 50%, 23%, 90% for Fungitell® and 68%, 63%, 28%, 91% for Dynamiker®, respectively. Statistically significant correlation was found between the assays (X2 (4)=121.7, p<0.0001) with 85% agreement and 6% major discrepancies (Fungitell® negative/positive Dynamiker® positive/negative and vice versa).

Conclusions: The Dynamiker® Fungus BDG assay is a useful complementary test for diagnosing IA, with technical flexibility to assist laboratories that process a small number of samples.

Presenter email address: [email protected]

2020

abstract No: 

5432

Full conference title: 

European Congress of Clinical Microbiology and Infectious Diseases 2020
    • ECCMID 30th (2020)