February 27, 2019
2 min read

Karius Test identifies pathogens more quickly than standard tests

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The Karius Test has been validated for detecting pathogens and was shown to identify them quicker than conventional tests, according to study findings published in Nature Microbiology.

“More than 1,000 microorganisms are known to cause human disease, collectively causing approximately 5 million hospitalizations per year in the United States. Early pathogen identification is key to targeting effective therapy, but identification of the causative pathogen remains challenging in many clinical scenarios,” Timothy A. Blauwkamp, PhD, chief scientific officer and cofounder of Karius, Inc., and colleagues wrote.

“Many common pathogens are difficult or impossible to culture outside the body, deep-seated infections often require invasive biopsy of infected tissue to make a diagnosis and the administration of broad-spectrum antibiotics before etiological identification frequently confounds specific diagnoses that would enable more effective and less toxic antimicrobial therapy.”

Blauwkamp and colleagues used a prospective, observational study to validate the Karius Test, a noninvasive blood test they reported can identify more than 1,000 clinically relevant bacteria, DNA viruses, fungi and parasites. According to the study, the test’s accuracy, precision, bias and robustness to several metagenomics-specific challenges were evaluated in 350 patients with sepsis.

Results showed that the test had a sensitivity of 93.7% (95% CI, 84.5-98.2) compared with blood culture and a sensitivity of 92.9% (95% CI, 88.1-96.1) compared with a composite reference standard.

Additionally, Blauwkamp and colleagues found that the time to diagnosis was potentially shorter than standard-of-care testing. According to the researchers, the median time from blood draw to test result for the first 2,000 samples was 53 hours — compared with more than 92 hours for conventional testing — with 85% of results delivered the day after the samples were received and more than 50% identifying at least one microorganism.

“The performance characteristics reported here point toward clinical applications in which the benefits of sensitivity, noninvasive sampling and broad testing outweigh the limitations of sequencing cost, turn-around time and identification of microorganisms beyond those related to a specific indication,” they wrote.

“In light of these trade-offs, use cases that could potentially benefit from this approach include rule-out testing for sepsis when the standard of care was not sensitive enough or too invasive, testing immunocompromised patients presenting with nonspecific symptoms of infection or testing before invasive procedures with high cost or morbidity. Future studies that directly examine clinical utility will be important to establish the specific indications for which microbial [cell-free DNA] sequencing should be used.” – by Caitlyn Stulpin

Disclosures: Blauwkamp is an employee of Karius, Inc. Please see the study for all other authors’ relevant financial disclosures.