Karius Test

The Karius test is a liquid biopsy that leverages next-generation sequencing to identify and quantify microbial cell-free DNA (cfDNA) from over 1,500 pathogens, including bacteria, DNA viruses, fungi, and parasites. Traditional infectious disease diagnostic methods, including blood cultures, serologies, and polymerase chain reaction (PCR) assays, face limitations in sensitivity, specificity, and the time required to obtain results.

Unlike tissue biopsies or other invasive diagnostic procedures (bronchoscopy, needle biopsy, etc.), the Karius test requires only a blood sample, making it a safer option, particularly for immunocompromised patients who may have difficulty tolerating invasive procedures. Whereas traditional blood cultures can take days to weeks to yield results and may not detect fastidious or slow-growing organisms, the Karius test provides a rapid (24-48 hours) and comprehensive diagnostic assay to facilitate prompt and targeted treatment.

Blauwkamp et al. showed that the Karius test identified pathogens in 73% of cases, compared to 24% with blood cultures, in a study involving immunocompromised patients with suspected infections. Additionally, a retrospective analysis by Hogan et al. (2020) evaluated the use of Karius testing in pediatric patients with febrile neutropenia. The results showed that the Karius test identified pathogens missed by conventional methods and facilitated earlier and more appropriate antimicrobial therapy.

As a cardiovascular ICU intensivist, I’ve seen the Karius test ordered in pathologies that could be associated with infection. It has certainly helped guide targeted antimicrobial therapy. As evidence continues to mount, the Karius test is poised to become integral to the infectious disease diagnostic landscape.

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