New DNA Test Gives Early Warning for Infections
Researchers at St. Jude have shown that microbial cell-free DNA sequencing can predict dangerous bloodstream infections in children with leukemia. The test can identify a coming infection days before any symptoms appear, offering a critical window for early treatment.
This new method of detecting microbial cell-free DNA (mcfDNA) in a patient's blood can identify a wide range of pathogens, including bacteria, DNA viruses, fungi, and parasites. The test is sensitive enough to detect fragments of DNA from these microbes even when the organisms themselves are no longer alive or detectable by traditional methods. The current standard for detecting bloodstream infections is the blood culture, a method that can take days to produce results and often fails to identify the specific pathogen causing the illness. This delay is particularly dangerous for children with leukemia, as their weakened immune systems leave them vulnerable to fast-progressing infections. Infections are a leading cause of death for children undergoing leukemia treatment. The St. Jude study, published in *The Lancet Microbe*, demonstrated that mcfDNA sequencing could predict bloodstream infections in high-risk pediatric leukemia patients up to three days before the onset of symptoms. This early warning provides a critical opportunity for preemptive treatment before the patient becomes seriously ill. The technology is not entirely new; a commercial version of the test, known as the Karius Test, has been available since 2017 and can identify over 1,000 different pathogens from a single blood sample. This broad range is a significant advantage over targeted tests that look for a specific microbe. Beyond this specific application, cell-free DNA (cfDNA) is a rapidly advancing field in diagnostics. It is already being used for noninvasive prenatal screening and in oncology as a "liquid biopsy" to detect and monitor cancers. The application of cfDNA for infectious disease is a promising expansion of this technology. While the results are promising, the widespread clinical adoption of this test will require further study and integration into existing healthcare systems. The process for a new diagnostic test to become a standard of care involves extensive research, clinical trials, and regulatory approval.
