Host Transcriptomics and Culture‐Independent Testing for the Management of Febrile Neutropenia: Data From an Observational Study Conducted in a Bone Marrow Transplant Unit

BACKGROUND: Managing febrile neutropenia is challenging due to the limited sensitivity of blood culture (BC) and the lack of tools differentiating infectious from non-infectious fever. T2 magnetic resonance (T2MR) is a culture-independent system detecting bacteria (T2Bacteria) and yeasts (T2Candida); SeptiCyte RAPID is a host response assay providing a likelihood of sepsis (SeptiScore). METHODS: We conducted an observational study including bone marrow transplant patients with febrile neutropenia to assess (1) the performance of T2MR versus BC (2) the performance of SeptiScore in providing valid results and diagnosing infection compared to a retrospective clinician diagnosis. RESULTS: We included 90 febrile episodes. Eleven episodes had BC growing bacteria, of which 3/11 were T2Bacteria on-panel pathogens. T2Candida identified four Candida with a turnaround time of 3.0 h (IQR 3.0-3.0), significantly shorter than BC (42.4 h, IQR 39.8-50.9, p = 0.014). A SeptiScore was obtained in 86/90 cases. Febrile episodes were classified as: infectious (21/86, 24%), probably infectious (13/86, 15%), indeterminate (excluded from analysis; 40/86, 46%), non-infectious (12/86, 14%). The AUC of SeptiScore for infectious fever was 0.84 (95% CI 0.71-0.97). CONCLUSION: Despite the short turnaround time, T2MR showed limited coverage of bloodstream pathogens. SeptiScore may help in diagnosing infectious neutropenic fever, but larger studies should clarify its clinical utility.