Of the 167 NGS tests performed, 118 (71%) were positive. The average time from collection to the receipt of the sample at the Karius laboratory was 2 days (SD, 1), and the average time from collection to the receipt of the results from Karius was 3 days (SD, 1). We sought to quantify the changes in antimicrobial management in both immunocompromised and immunocompetent patients who had an NGS test performed.ġ Leukocytosis defined as white blood cell count of greater than 12.00 x 10 3/mcL Reference Hogan, Yang and Garner8– Reference Rossoff, Chaudhury and Soneji10 Given the high sensitivity and corresponding low false-negative rate of the Karius test, we hypothesized that physicians would change their antimicrobial management following the receipt of NGS results, making it a possible antimicrobial stewardship tool. A few retrospective cohort studies have been conducted to measure the clinical impact of plasma NGS testing, with differing outcomes and conclusions. However, data regarding how NGS testing affects the antimicrobial prescribing practices of physicians are limited. Research is available regarding NGS tests aiding in the diagnosis of infections in human immunodeficiency virus (HIV) patients, Reference Zhou, Hemmige, Dalai, Hong and Muldrew3 allogeneic hematopoietic stem-cell transplant patients, Reference Fung, Zompi and Seng4 sepsis, Reference Blauwkamp, Thair and Rosen2 central nervous system (CNS) infections, Reference Kalyatanda, Rand and Lindner5 cardiac infections, Reference Downey, Russo and Hauger6 and respiratory Reference Farnaes, Wilke and Ryan Loker7 infections. Plasma NGS tests are increasingly used as a diagnostic tool in infectious disease. A report containing a list of pathogens found in the plasma sample along with the quantitative concentration of the microbial cell-free DNA Reference Blauwkamp, Thair and Rosen2 is sent to the ordering physician. Reference Blauwkamp, Thair and Rosen2 Plasma samples are collected from the patient and shipped to the Karius laboratory, where cell-free DNA are extracted and compared against a proprietary reference genome database to identify clinically relevant microbial DNA fragments in the plasma. Cell-free DNA has an estimated half-life in the circulation of 95% and >99%, respectively, and the clinical sensitivity and specificity are 93% and 63%, respectively. This technology relies on the sequencing of small fragments of circulating DNA in the cell-free component of the blood called cell-free DNA. Metagenomic next-generation sequencing (NGS) is an ideal platform to meet this need because it is both sensitive and rapid. Unfortunately, yield from cultures have been inconsistent and slow, prompting the need for faster and more sensitive methods. Analysis of microbiological culture data is a longstanding gold standard in diagnostics.
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