gms | German Medical Science

Invasive Aspergillosis (IA) is a life threatening infection, which particularly affects immunocompromized patients with hematologic malignancies, those receiving solid organ transplants or undergoing hematopoietic stem cell transplantation. A delayed or inappropriate treatment of this disease due to diagnostic issues is associated with an inverse outcome of IA.

Use of Aspergillus RNA biomarkers for IA diagnosis could respond to the need for early pathogen detection as well as for monitoring progression of infection and treatment outcome. In fact, RNA detection may improve the sensitivity of fungal detection (multicopy target) and offer the possibility to assess fungal metabolic status (active growth indicator). However, evaluation of Aspergillus RNA as an IA biomarker is considerably under-reported in the literature due, presumably, to the technical challenges inherent to RNA manipulation.

This work presents a prototype aiming to detect fungal RNA in whole blood, which is compliant with the recommendations of European Aspergillus PCR Initiative (EAPCRI) for the sample preparation part. Aspergillus fumigatus is the first targeted species as it causes the majority of reported IA cases. The bioMérieux platform easyMAG® system enabled optimizing a modular procedure that is used for sample preparation (pretreatment/lysis and fungal RNA extraction/purification) from spiked healthy donor whole blood. Subsequently, detection of fungal RNA is carried out using One Step Real Time RT-PCR and two fungal RNA markers (A and B) as molecular targets.

The presented data will include analytical performance assessments in terms of sensitivity of the prototype, specificity (cross-reactivity, false positivity) of the used One step RT-PCR designs and interference by human RNA and/or blood extracts. This prototype will be clinically evaluated on a retrospective whole blood sample collection coming from hematological patients.

Note: The authors J. Springer, M. Lackner, C. Lass-Flörl, J. Löffler, H. Einsele, J. Yugueros-Marcos, and A. Apostolaki belong to the aspBIOmics consortium funded by the ERA-NET Pathogenomics Action.