Karius Test | Karius

The Karius Test

Plasma NGS for Pathogen Detection

A quantitative next-generation sequencing test to help clinicians rapidly diagnose infectious diseases. Our analytically validated assay identifies microbial cell-free DNA in plasma from bacteria, DNA viruses, fungi, molds and protozoa.

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DNA Viruses

Other Eukaryotes


Detect 1,000+ pathogens from a single non-invasive blood draw with next day results.*

The full list of pathogens detected by the Karius® Test is available here.

*for about 80% of specimens received by 8:30 a.m. Monday to Saturday



Accurately detect pathogens in diagnostically challenging or culture-negative infections, including sepsis, endocarditis, fever of unknown origin, and patients who have received antibiotic pre-treatment

Quickly identify deep-seated infections such as invasive fungal infections that might otherwise require invasive biopsies

Actively monitor immunocompromised patients susceptible to a broad range of pathogens, including stem-cell transplant recipients

Precisely target antimicrobial therapy in cases where blood cultures are negative, including febrile neutropenia and infections with fastidious organisms

How It Works

Clinical scenarios

Immunocompromised, Pneumonia, Febrile neutropenia, Sepsis, Culture-negative endocarditis, Fever of unknown origin


Preferred specimen

5.0 mL whole blood collected in BD Vacutainer® PPT™ tube, centrifuged at 1,100 RCF for 10 minutes, and shipped to Karius laboratory at ambient temperature. Must be received within 96 hrs (4 days) of collection.


Alternative specimen

Minimum 0.7 mL of plasma isolated from whole blood collected in K2-EDTA tube within 24 hours of draw by centrifugation of the specimen at 1,600 RCF for 10 minutes and transferred to a sterile polypropylene tube. Ship to Karius laboratory at ambient temperature. Must be received within 96 hours (4 days) of collection.



Test results are sent as a one-page report displaying quantities of pathogens detected at statistically significant levels. See a sample test report here, and find detailed instructions here.


Order Karius Test

PPT Tube
5 mL standard blood draw


Specimen Processing
DNA extraction and library preparation

Pathogen DNA sequenced

dna analysis

Curated clinical-grade microbe database

Quantitative amounts of clinically relevant pathogens

Clinical diagnostic performance of the Karius Test

The SEP-SEQ study compared performance of the Karius Test to blood culture and a clinical reference standard of all microbiologic testing and clinical diagnosis. The study involved 348 patients with suspected sepsis. Clinical diagnosis was based on clinical adjudication by a panel of infectious disease physicians incorporating laboratory data, radiology results, and discharge summaries. Results of the study are summarized below.


Karius Test Agreement with Blood Culture in Sepsis

Positive Agreement with Blood Culture: 93.7% (59/63)


Since the Karius Test can also detect DNA viruses, unculturable bacteria, and eukaryotic pathogens, discordant results were compared against a composite gold standard including laboratory, radiology, and clinical data.


Overall Test Performance in Sepsis vs. Clinically Adjudicated Composite Reference Standard1

    Clinical Diagnosis
    + -
Karius + 170 61
  - 13 104

Sensitivity: 92.9%
Specificity: 63.0%

                    1 Determined by all microbiologic testing performed +/- 7 days of enrollment, radiographic data, and clinical data.