866: DETERMINING THE LIKELIHOOD OF BLOOD CULTURE POSITIVITY IN SEPSIS IN ONE HOUR USING SEPTICYTE RAPID

Introduction: Direct pathogen detection technologies, such as multiplexed PCR [1-5] or the CANARY system [6], are important in military & civilian applications but are not available commercially. Host-response assays, such as SeptiCyte RAPID, are complementary by detecting immune dysfunction in response to blood-stream infections (BSI) leading to sepsis. Advantages of this assay include short turnaround time (TaT, 1 hr) and being pathogen agnostic [7] whereas blood cultures take 13-30 hrs to become positive & have a low yield. This work evaluates the performance of SeptiCyte RAPID in blood culture positive (BC+) sepsis patients from multiple hospitals in the US, Europe & Africa [8]. Methods: The study comprised 205 BC+ sepsis patients from a cohort of 1061 patients suspected of sepsis. Sepsis adjudication for the entire cohort was done retrospectively by external panelists or treating physicians using sepsis-2 or 3 criteria. The control group were either classified as Systemic Inflammatory Response Syndrome/ Inflammation or No-Sepsis; Indeterminates (n=53) were excluded. A blood sample was drawn for SeptiCyte RAPID within the first day of admission. SeptiCyte RAPID reports a likelihood of sepsis on a scale of 0-15 (SeptiScore) falling into four bands and is available on a near-patient platform. Blood cultures were collected if they were deemed clinically necessary. Results: From 205 BC+ sepsis patients, 84 were Gram+, 107 were Gram- & 14 were mixed (both Gram+ & Gram-). The ROC-AUC for differentiating all BC+ sepsis vs. SIRS (n=356) was 0.90, for Gram+ 0.88, for Gram- 0.92, for mixed (Gram+ & Gram-) 0.87, & for Gram+ (S.aureus only) 0.88. For multi-drug resistant ESKAPE pathogens (n=54) (E. faecium, S. aureus, K. pneumoniae, A. baumannii, P. aeruginosa, Enterobacter spps.) [9], AUC was 0.91. Conclusions: SeptiScore correlated to likelihood of blood culture positivity regardless of Gram-status. Most BC+ sepsis patients had high SeptiScores (93.7% in Bands 3/4) including those positive for ESKAPE pathogens. These results, in combination with a short TaT and using near-patient technology, suggest that SeptiCyte RAPID can be used to guide blood culture practice such as implementing blood culture orders for patients presenting with high SeptiScores if not originally drawn.