Cambridge helps find new test to fight killer infections
Cambridge University researchers have helped develop a new test to identify patients at greatest risk from killer bugs in intensive care – offering the prospect of accelerating the development of new treatments for those most at risk.
Patients in intensive care units are at significant risk of potentially life-threatening secondary infections, including from antibiotic-resistant bacteria such as MRSA and C. difficile.
Infections in intensive care units tend to be caused by bugss, such as multi-resistant gram-negative bacteria found in the gut, that are resistant to frontline antibiotics. Treating such infections means relying on broad spectrum antibiotics, which run the risk of breeding further drug-resistance, or antibiotics that have toxic side-effects.
Estimates of the proportion of patients in ICU who will develop a secondary infection range from one in three to one in two; around a half of these will be pneumonia. However, some people are more susceptible than others to such infections and evidence suggests that the key may lie in malfunction of the immune system.
In a study published in the journal Intensive Care Medicine, a team of researchers working across four sites in Edinburgh, Sunderland and London, has identified markers on three immune cells that correlate with an increased risk of secondary infection. The team was led by researchers at the Universities of Cambridge and Edinburgh and biotech company BD Biosciences.
“These markers help us create a ‘risk profile’ for an individual,” explains Dr Andrew Conway Morris from the Department of Medicine at the University of Cambridge. “This tells us who is at greatest risk of developing a secondary infection.
“In the long term, this will help us target therapies at those most at risk, but it will be immediately useful in helping identify individuals to take part in clinical trials of new treatments.”
Clinical trials for interventions to prevent secondary infections have met with mixed success, in part because it has been difficult to identify and recruit those patients who are most susceptible, say the researchers. Using this new test should help fine tune the selection of clinical trial participants and improve the trials’ chances of success.
The markers identified are found on the surface of key immune cells: neutrophils (frontline immune cells that attack invading pathogens), T-cells (part of our adaptive immune system that seek and destroy previously-encountered pathogens), and monocytes (a type of white blood cell).
• PHOTOGRAPH SHOWS: Dr Andrew Conway Morris