A pioneering same-day diagnostic tool is proving life-saving for children in intensive care by identifying complex, hidden infections that traditional methods often overlook. Known as metagenomic testing, this process sequences all genetic material present in a clinical sample, allowing for a comprehensive view of pathogens that standard Victorian-era culture techniques or targeted PCR tests cannot detect. In contrast to conventional methods where clinicians need to decide in advance what they’re looking for, the team at GOSH used metagenomics – a diagnostic test that works by sequencing all genetic material present. By contrast, the most common method of identifying bacteria is by trying to culture them in Petri dishes, a technology that has been used since Victorian times.
The impact of this technology was evident in the case of 10-year-old Willow Crowther from Kent, who was admitted to Great Ormond Street Hospital (GOSH) in March with severe pneumonia. Her condition deteriorated rapidly, leading to a seizure and multiple cardiac arrests. With her survival chances estimated at only 50%, her family was warned to prepare for the end. The metagenomic test proved to be the turning point, identifying a specific drug-resistant bacterial infection that required a different treatment than the one she was initially prescribed. After receiving the correct antibiotic, Willow recovered and eventually celebrated her 10th birthday in August. Respiratory samples from more than 100 critically ill young patients at London’s Great Ormond Street Hospital (GOSH) were sent for what is known as metagenomic testing., external. The consultant said… we should bring our family up to say goodbye to her. This is how critical and in how much danger she was of passing away. With the right treatment, Willow was eventually able to recover from her infection, but needed several months in hospital.
Reflecting on the experience, Willow’s mother, Stacey Moore, stated that having access to this test was paramount to her survival, while her father, Russ, described her recovery as a miracle. Between 2024 and 2025, GOSH researchers conducted a study on 122 critically ill children in their paediatric intensive care unit. The results, published in the Lancet Microbe, revealed that the testing successfully identified approximately nine out of ten bacteria and viruses, along with every fungus present in the samples analyzed. Viruses and fungi from a single sample, which in many cases influences what doctors prescribe, it can identify bacteria. It’s a miracle she’s here and we’re extremely grateful for that,” added Willow’s dad, Russ. During a study in 2024-5 metagenomic testing was used on 122 critically ill children in the paediatric intensive care unit (ICU) at GOSH.
Beyond immediate patient care, the findings highlight a shift in clinical practice. In 25% of the cases studied, the metagenomic results directly influenced prescribing decisions, whether by initiating specific treatments, changing antibiotics, or ceasing medication when it was found to be ineffective. Dr. Sam Ray, a consultant in paediatric intensive care medicine at GOSH and co-author of the study, noted that this capability is vital for both immediate outcomes and the broader fight against antimicrobial resistance by eliminating unnecessary treatments.
The system also serves as a robust surveillance mechanism. During the GOSH project, testing detected 50 organisms that routine diagnostics missed, suggesting the technology could act as an early warning system for novel pathogens. Dr. Julianne Brown, head of the GOSH Metagenomics Service, emphasized the potential for identifying mystery pathogens that could trigger future pandemics. The service is currently being expanded, with a rollout underway to approximately 30 intensive care units across the UK treating both adult and child patients. This initiative builds on foundational trials at Guy’s and St Thomas’ NHS Trust, which initially pioneered the use of metagenomics to screen for respiratory infections in adults. 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, in the future.
