Sepsis – DNA fragments may offer a key to diagnosis
A new ‘bedside’ test that quantifies webs of DNA is now being trialled in the NHS to help identify potential sepsis
A blood test to help detect patients at risk of sepsis is being trialled at Guy’s and St Thomas’ NHS Foundation Trust.
The test looks for a protein associated with a type of DNA web found outside the cells that is part of the immune response to infection. The test can return results within 45 minutes, which allows patients to receive antibiotics within one hour, in line with NHS protocols.
“Sepsis is the number one cause of death in hospitals, and mortality increases as much as 8% for every hour that treatment is delayed,” said critical care consultant Dr Andrew Retter, who is leading the trial. “Being able to spot those patients most at risk of sepsis using a simple blood test … could save thousands of lives every year.”
What is sepsis?
Sometimes called ‘blood poisoning’, sepsis is a life-threatening condition that contributes to around 48,000 deaths every year in the UK. It occurs when the body’s immune system overreacts to an infection. The immune system attacks the body’s organs and can quickly result in organ failure and death if not treated in time.
Sepsis can be triggered by many different infectious agents, including viruses, bacteria or fungi. It can be difficult to identify because early symptoms mirror common respiratory infections, and there is currently no diagnostic test for it.
Sepsis can affect anyone but is more common in babies, older people, people who have diabetes or are immunosuppressed, or people who have recently had a surgical procedure or given birth.
What does the new test look for?
The immune system is complex, but part of its first line of defence against an infection is a type of immune cell called a neutrophil. Neutrophils can release webs of DNA and proteins, termed neutrophil extracellular traps (NETs). These NETs bind to microbes and damage them.
When the immune system goes into overdrive, as in sepsis, an excessive number of NETs are released. The new rapid blood test measures the levels of one of the proteins that are part of the NETs. High levels of the protein indicate high levels of NETs – which means a patient is more likely to have or develop sepsis.
Uses for the test
The test is not a conclusive diagnostic test, but it aims to provide clinicians with information to help them spot signs of sepsis earlier in hospital patients or contribute to a diagnosis in patients who present with symptoms. Early results from other trials of the test indicate that it can identify patients who are at a higher risk of developing sepsis and progressing to organ failure.
The study, which launched in November 2023, will run for a year and test the levels of NETs in 450 sepsis patients in the intensive care unit at St Thomas’ Hospital, as well as 50 cardiology patients as controls.
The results will be compared to current blood tests to see if testing for NETs could improve diagnosis. If it is successful, the test could be rolled out more widely, including screening patients who present at A&E, as well as planning which patients will be admitted and discharged from critical care.
