According to a study performed by researchers at St. Jude Children’s Research Hospital, the Karius test from Karius, Redwood City, Calif, detects bloodstream infections in high-risk pediatric patients with relapsed or refractory leukemia before the onset of clinical symptoms.1 The study provides the first evidence that the Karius test can predict infections.
The Karius test is a noninvasive blood test that uses next-generation sequencing of microbial cell-free DNA to detect more than 1,400 bacteria, DNA viruses, fungi, and parasites. The test is primarily used to detect specific causative pathogens in cases of complicated pneumonia, cardiovascular infection, and infections in immunocompromised patients.

Josh Wolf, MD, PhD, St. Jude Children's Research Hospital.

Josh Wolf, MD, PhD, St. Jude Children’s Research Hospital.

In the United States, infections are a leading cause of death for patients with leukemia. Patients treated with chemotherapy for cancers such as leukemia have a high risk of life-threatening infections. Some children with leukemia have a higher chance of dying from an infection than from the cancer itself.

Currently, broad-spectrum antimicrobial prophylaxis is used to prevent infections, and empiric antimicrobial treatment is started at the onset of signs or symptoms of infection. A noninvasive plasma-based predictive screening test for infections may allow preemptive targeted antimicrobial therapy before symptom onset and could improve clinical outcomes.

“Parents of children with cancer often wish that they had a crystal ball to know what’s coming next; this might just be that,” says Josh Wolf, MD, PhD, coauthor of the paper and associate member of the department of infectious diseases at St. Jude Children’s Research Hospital.

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 bloodstream infections in 75% of cases (12 out of 16) as early as 3 days before patients became symptomatic.

Asim Ahmed, MD, Karius.

Asim Ahmed, MD, Karius.

“There is an important signal here suggesting an ability to predict infections in this vulnerable population even before the development of clinical symptoms,” says Asim Ahmed, MD, coauthor and senior medical director at Karius. “The Karius test is not currently a screening test; additional studies are needed to guide how this test can be used in the clinical workflow to help predict and prevent infections in patients with immunocompromising conditions.”

For more information, visit Karius.


  1. 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. Epub ahead of print, December 19, 2019; doi: 10.1001/jamaoncol.2019.4120.