Karius Test Can Detect Blood Stream Infections Before Symptoms in High Risk Patients Interview with:

Dr. Asim Ahmed MD

co-author of the study
Senior medical director at Karius What is the background for this study? Would you briefly explain the basis of the Karius Test?

Response: The Karius Test is a non-invasive blood test that uses next-generation sequencing of microbial cell-free DNA to rapidly detect over 1,400 bacteria, DNA viruses, fungi, and other pathogens. Doctors primarily use the test to detect specific causative pathogens, complicated pneumonia, cardiovascular infections, and infections in immunocompromised hosts.

The Karius Test is transforming how doctors diagnose infectious diseases by helping doctors identify the precise pathogens infecting patients.

The Karius Test offers a higher diagnostic yield and faster time-to-diagnosis than conventional tests – with the potential to eliminate invasive diagnostic procedures like biopsies.  If there are no symptoms, when would the Karius Test be indicated?

Response: Currently for commercial use, the Karius Test is not a screening test and is not recommended in the absence of a clinical concern for infection. Given the study recently published by Dr. Wolf and colleagues at St. Jude there is a potential for the test to be used in the future to screen for infections in high-risk populations. Additional studies are needed to guide how this test might be used in the clinical workflow to help predict and prevent infections in patients with immunocompromising conditions. What are the main findings? What types of infections would be indicated?  (bacterial, fungal, viral?).

Response: The study findings demonstrated the Karius Test’s ability to detect blood stream infections before the onset of clinical symptoms in high-risk pediatric patients with relapsed or refractory leukemia.

Of the 47 pediatric patients enrolled in the study, 12 patients developed a total of 19 bloodstream infections, and samples for evaluation of predictive diagnosis were available for 16 episodes. The Karius Test detected a bloodstream infection in 75% percent of cases (12/16) as early as three days before patients became symptomatic. What should readers take away from your report?

Response: Patients treated with chemotherapy for cancer are at a high risk of life-threatening infection; some children with leukemia have a higher chance of dying from infection than from their cancer. It is critical that doctors are able to detect infections early and begin targeted treatment for these high-risk patients. These findings suggest that it may be possible to shift the paradigm of infection treatment from reactive to proactive, with patients beginning pre-emptive targeted antimicrobial therapy before symptoms occurred – improving clinical outcomes. What recommendations do you have for future research as a result of this work?

Response: The Karius Test is not currently a screening test. Additional studies are needed to guide how this test can be used in the clinical work-flow to help predict and prevent infections in patients with immunocompromising conditions.

Any disclosures? I am an employee of Karius.


Goggin KP, Gonzalez-Pena V, Inaba Y, et al. Evaluation of Plasma Microbial Cell-Free DNA Sequencing to Predict Bloodstream Infection in Pediatric Patients With Relapsed or Refractory Cancer. JAMA Oncol. Published online December 19, 2019. doi:


Last Modified: [last-modified]

The information on is provided for educational purposes only, and is in no way intended to diagnose, cure, or treat any medical or other condition. Always seek the advice of your physician or other qualified health and ask your doctor any questions you may have regarding a medical condition. In addition to all other limitations and disclaimers in this agreement, service provider and its third party providers disclaim any liability or loss in connection with the content provided on this website.


Last Updated on December 21, 2019 by Marie Benz MD FAAD