A single blood draw. Metagenomics and AI. More than a thousand infections on the table - often within a day.
When a patient is critically ill and no one can name the infection, medicine has long relied on a slow, imperfect ritual: draw blood, wait for something to grow in a culture, and hope it grows in time. Karius, a life-sciences company based in Redwood City, California, was built to ask a different question - not what will grow, but what is already there.
The company's flagship product, the Karius Test, looks for microbial cell-free DNA, or mcfDNA - tiny fragments of a pathogen's genetic material that circulate in the bloodstream even at very low concentrations. Using next-generation sequencing, metagenomics and machine learning, it can screen a single blood sample for more than 1,000 organisms at once: bacteria, DNA viruses, fungi, molds and parasites. Results typically come back within a day of the lab receiving the sample.
That breadth is the point. A conventional workup often tests for one suspected culprit at a time. Karius casts a wide net in a single pass, which matters most for the patients standard tests serve worst - the immunocompromised, transplant recipients, and cancer patients whose infections can hide behind negative cultures.
The approach is a form of liquid biopsy, the same broad idea that reshaped prenatal testing and cancer screening. Karius pointed it at infection. The result is a test now used across more than 400 healthcare institutions in the United States, including over 90 transplant centers and more than 40 children's hospitals.
"Our vision is to create a world where every patient gets a clear and timely diagnosis." - Karius, on its mission
Karius was founded in 2014 by Mickey Kertesz and Tim Blauwkamp, spun out of the Stanford lab of bioengineer Stephen Quake - the same lineage behind non-invasive prenatal testing. The pair had been studying cell-free DNA to detect organ-transplant rejection when they noticed something unexpected: microbial DNA kept showing up in patient blood samples.
Rather than filter out the signal, they built a company around it. Kertesz, who previously founded the long-read sequencing startup Moleculo (acquired by Illumina in 2012), became CEO; Blauwkamp became Chief Scientific Officer. In 2020, industry veteran Alec Ford joined as CEO to lead the company's commercial scale-up.
Mickey Kertesz - Co-founder & former CEO. Former Moleculo founder; Quake-lab postdoc.
Tim Blauwkamp - Co-founder & Chief Scientific Officer. Co-discovered the mcfDNA signal.
Stephen Quake - Scientific co-founder. Stanford bioengineer whose lab produced the technology.
Alec Ford - CEO (since 2020). Three decades in life sciences, leading commercial expansion.
In infectious disease, time-to-answer is not a convenience - it decides which drug a patient gets, or whether a clinician has to guess. Broad-spectrum antibiotics prescribed blindly also feed the antimicrobial resistance crisis, one of the drivers behind Karius's most recent funding round.
In a published pneumonia trial, the Karius Test identified as many causes of disease in 24 hours as hospitals found in seven days of standard microbiological testing - and detected roughly 40% more infections when added to the standard workup.
Separate retrospective studies at tertiary-care centers found the test changed antibiotic treatment in a meaningful share of patients, with the greatest impact in neutropenic fever and endocarditis.
A metagenomic mcfDNA blood test detecting 1,000+ pathogens - bacteria, DNA viruses, fungi and parasites - from a single non-invasive draw, typically within a day of receipt.
An mcfDNA test run on bronchoalveolar lavage fluid to identify pathogens behind pneumonia and other lung infections, detecting 500+ organisms.
The mcfDNA platform is used by biopharmaceutical partners for infection surveillance, trial endpoints and research within clinical studies.
"Detecting the microbes that impact human health." - Karius tagline
Blood cultures try to grow an organism; syndromic PCR panels test for a fixed, pre-chosen list. Karius does neither. It sequences whatever pathogen DNA is circulating, so a single assay can surface many organisms at once - including ones a clinician never thought to order. It is designed to work alongside the microbiology lab, catching what culture misses rather than displacing it.
Runs a CLIA-certified, CAP-accredited high-complexity lab; sells tests to hospitals and health systems per test and via institutional agreements, plus biopharma partnerships.
Infectious-disease physicians, oncologists and transplant teams treating immunocompromised and critically ill patients across 400+ institutions.
Competes with metagenomic and molecular diagnostics such as Delve Bio, IDbyDNA/Illumina, Day Zero, BioFire panels and traditional culture and PCR workflows.
Kertesz and Blauwkamp spin the company out of Stephen Quake's Stanford lab.
Raises $50M and brings the Karius Test to market.
SoftBank and General Catalyst lead a large round; Alec Ford named CEO.
Clears New York's demanding clinical-lab review for the liquid-biopsy test.
Funds broader access and the antimicrobial-resistance mission.
Nationwide launch of the mcfDNA test for lung infections.
It analyzes microbial cell-free DNA in a single blood sample to detect more than 1,000 pathogens - bacteria, DNA viruses, fungi and parasites - usually within a day of the lab receiving the sample.
Hospitals, health systems, transplant centers and children's hospitals - over 400 institutions - mainly to diagnose infections in immunocompromised and critically ill patients where standard cultures often fall short.
Instead of trying to grow an organism, Karius sequences fragments of pathogen DNA circulating in plasma, so it can detect many organisms at once, non-invasively, and often faster than culture.
It was founded in 2014 by Mickey Kertesz and Tim Blauwkamp, based on research from Stephen Quake's lab at Stanford University.
Roughly $345M across Series A through C, including a $100M Series C in 2024 co-led by Khosla Ventures, 5AM Ventures and Gilde Healthcare.