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]
Full conference title:
- ECCMID 30th (2020)