New Metagenomic Test Aids Detection of Infections in Critically Ill Children

A new diagnostic method called metagenomic testing is helping doctors identify hidden infections in critically ill children, potentially saving lives and guiding crucial treatment decisions. This advanced testing, which analyzes all genetic material within a sample, has demonstrated a significant ability to detect a wide range of pathogens, including bacteria, viruses, and fungi.

During a study conducted in 2024-2025 at Great Ormond Street Hospital (GOSH) in London, metagenomic testing was employed on 122 children in the pediatric intensive care unit (ICU). The findings, published in The Lancet Microbe, indicate that the test successfully identified approximately nine out of ten bacteria and viruses, as well as all fungi present in patient samples.

This contrasts with traditional methods, such as culturing bacteria in Petri dishes, a technique dating back to the Victorian era, or PCR tests, which require clinicians to specify the pathogen they suspect. Metagenomic testing offers a broader scope, analyzing thousands of different pathogens simultaneously.

In a quarter of the cases in the GOSH study, the results of the metagenomic tests directly influenced prescribing decisions. This included initiating, stopping, or altering antibiotic treatments. Dr. Sam Ray, a consultant in pediatric intensive care medicine at GOSH and co-author of the study, highlighted the test's advantage over educated guesswork required with traditional diagnostics.

"The study has helped us to spot infections we would have missed, get children on the right treatment and stop antibiotics when we know they aren't going to work," Dr. Ray stated. "Removing unnecessary treatment is incredibly important for the fight against growing antimicrobial resistance."

The GOSH metagenomic service also identified 50 organisms that routine diagnostics had missed, suggesting its potential as an early warning system for novel infections. Dr. Julianne Brown, head of the GOSH Metagenomics Service and co-senior author of the study, noted that the technology is being gradually implemented across approximately 30 intensive care units in the UK, serving both adult and pediatric patients.

"It could be a powerful tool for identifying new infections that pose a pandemic threat," Dr. Brown commented. "In the future, if there was to be a new mystery pathogen that could be a cause of the next pandemic, we would detect that very quickly and put the right measures in place."

The project at GOSH builds upon earlier trials at Guy's and St Thomas' NHS Trust, where metagenomics was first used to test adult patients for respiratory infections. For critically ill children like Willow, whose father Russ described the test's availability as "paramount" and credited it with saving her life, such rapid and comprehensive diagnostic capabilities are vital. Willow eventually recovered after several months in the hospital, benefiting from the appropriate treatment initiated based on the test results.