Bacteremia evaluation with T2 magnetic resonance in the emergency room (BETTER)

Conventional blood culture (BC) is limited by long turnaround times and low sensitivity. The T2Bacteria is a novel culture-independent system identifying six bacteria from whole blood within a few hours. We conducted an observational study in an Australian Emergency Department to assess the performance of T2Bacteria, including its diagnostic accuracy, time to results, and potential role in early adjustment of antimicrobials. Patients with suspected bacteremia were enrolled and had BC drawn with T2Bacteria samples. We enrolled 101 patients. Thirty-five patients had positive BC, of which 31 (88.5%) grew T2Bacteria on-panel pathogens. Eight patients (26%) grew T2Bacteria on-panel pathogens in BC but had negative T2Bacteria results. Agreement between T2Bacteria and BC for T2Bacteria on-panel pathogens was 87.6%, sensitivity was 70.4%, and specificity 94.3%. Median time to results for T2Bacteria was 8.7 h, IQR 7.2-9.6, significantly shorter than time to Gram stain (17.0 h, IQR 12.2-21.6, P < 0.001) and MALDI-TOF MS (27.6 h, IQR 22.2-36.7, P < 0.001). Out of 19 patients with concordant T2Bacteria/BC results, T2Bacteria could have supported early antimicrobial de-escalation in seven cases (37%) and escalation in four cases (21%), including one case where antibiotics were not started based on suspicion of viral etiology, and three cases where the bloodstream pathogens were not covered by empirical antibiotics (S. aureus, n = 1, P. aeruginosa, n = 1, E. faecium, n = 1). T2Bacteria may support early escalation of antimicrobials in patients with suspected sepsis. Conversely, its narrow diagnostic panel and imperfect sensitivity do not support its use for early de-escalation.IMPORTANCEThis study evaluates the performance of T2Bacteria, a novel culture-independent test detecting six bloodstream pathogens directly from whole blood in 3-9 h, in patients with suspected sepsis admitted to the Emergency Department of an Australian hospital. Despite limitations in the diagnostic accuracy of T2Bacteria, in particular in its sensitivity, with some bacteremia episodes missed, we confirmed a much shorter turnaround time of T2Bacteria compared with conventional blood culture. These characteristics could support the use of T2Bacteria for early escalation of antimicrobials in cases of detection of pathogens not covered by empirical antibiotics, potentially reducing adverse clinical outcomes associated with exposure to ineffective antimicrobial regimens. Conversely, improved diagnostic performance and a broader diagnostic panel are likely required to recommend the use of T2Bacteria for early de-escalation. In our cohort, T2Bacteria supported early escalation in 4/19 cases with concordant BC and T2Bacteria results.