Plasma Microbial Cell-free DNA Next Generation Sequencing in the Diagnosis and Management of Febrile Neutropenia.

BACKGROUND Standard testing fails to identify a pathogen in most patients with febrile neutropenia (FN). We evaluated the ability of the Karius microbial cell-free DNA (mcfDNA) sequencing Test (KT) to identify infectious etiologies of FN and its impact on antimicrobial management. METHODS This prospective study (ClinicalTrials.gov; NCT02912117) enrolled and analyzed 55 patients with FN. Up to 5 blood samples were collected per subject within 24h of fever onset (T1) and every 2-3 days. KT results were compared to blood culture (BC) and standard microbiological testing (SMT) results. RESULTS Positive agreement was defined as KT identification of ≥1 isolate also detected by BC. At T1, positive and negative agreement were 90% (9/10) and 31% (14/45) respectively; 61% of KT detections were polymicrobial. Clinical adjudication by 3 independent infectious diseases specialists categorized Karius results as: unlikely to cause FN (N=0); Definite (N=12): KT identified ≥1 organism also found by SMT within 7 days; Probable (N=19): KT result was compatible with a clinical diagnosis; Possible (N=10): KT result was consistent with infection but not considered a common cause of FN. Definite, probable and possible cases were deemed true positives. Following adjudication, KT sensitivity and specificity were 85% (41/48) and 100% (14/14) respectively. Calculated time to diagnosis was generally shorter with KT (87%). Adjudicators determined real-time KT results could have allowed early optimization of antimicrobials in 47% of patients, by addition of antibacterials (20%) (mostly against anaerobes [12.7%]), antivirals (14.5%) and/or antifungals (3.6%); and antimicrobial narrowing in 27.3% of cases. CONCLUSION KT shows promise in the diagnosis and treatment optimization of FN.