October 11, 2017

Novel Blood Test Identifies Broad Range of Pathogens in Suspected Sepsis

By Denise Baez

SAN DIEGO -- October 11, 2017 -- A novel plasma next-generation sequencing (NGS) test can identify viruses, bacteria, and eukaryotic pathogens in patients with sepsis in a single blood draw, researchers reported here at ID Week 2017, the annual meeting of the Infectious Diseases Society of America (IDSA).

“The Karius plasma NGS assay can provide valuable information to help clinicians better target antimicrobial therapy for patients with sepsis,” reported Simone Thair, PhD, Stanford University Medical Center, Stanford, California, on October 7.

The plasma NGS test was used in 286 patients presenting to Stanford University Medical Center with signs and symptoms of sepsis. All patients received initial routine blood cultures.

Dr. Thair and colleagues sequenced the extracted plasma cell-free DNA, removed the human sequences, and aligned the remaining reads against a pathogen database. The team then compared results of the NGS assay with the initial blood cultures and subsequent microbial tests.

The plasma NGS test identified a broad range of pathogens -- DNA viruses; bacteria, including fastidious/unculturable bacteria; and fungi -- 3 times more often than blood culture and more often than all microbiology tests combined. The plasma NGS assay identified potential pathogens in 172 (60.1%) patients. An initial blood culture identified a potential pathogen in only 45 (15.7%) patients, and standard microbiology test identified a potential aetiology in 109 (38.1%) patients.

Of the 172 patients with a possible potential pathogen identified by the NGS assay, 140 (81.4%) were deemed to be consistent with the septic event, after clinical adjudication. Of the remaining 32 patients, 15 had NGS results that were plausible causes of sepsis, but there were not enough clinical data to confirm this.

A diagnostic test that can accurately identify the cause of sepsis is important to determine the most effective and appropriate antimicrobial therapy; however, a causative pathogen is not always identified in a large percentage (up to 40%) of sepsis cases.

The Karius plasma assay uses NGS to enable the broad and rapid detection of >1,250 pathogens from a standard blood draw.

[Presentation title: The SEP-SEQ Trial -- Clinical Validation of the Karius Plasma Next-Generation Sequencing Test for Pathogen Detection in Sepsis. Abstract LB-5]

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