Blood test spots patients’ infection risk

Patients in intensive care could be helped by a new test that pinpoints those at risk of developing secondary infections such as pneumonia.

Researchers said the test could eventually help doctors target therapies such as antibiotics at the patients most likely to benefit.

It could also help identify suitable patients to take part in clinical trials of new therapies and improve the chances of finding medicines that work.

Intensive care

Up to half of patients in intensive care develop a secondary infection during their stay in hospital, including lung infections, blood diseases and urinary tract infections.

Some people are more susceptible than others and research suggests this may be because their immune system doesn’t work properly.

Immune markers

Researchers led by the Universities of Cambridge and Edinburgh identified three markers on the surface of key immune cells in the blood that are involved in fighting infections.

These markers indicate that the cells are dysfunctional and, therefore, the patient is more susceptible to disease.


Patients who test positive for all three markers are two to three times more likely to develop an infection compared with those who test completely negative, the study found.

As intensive care specialists, our priority is to prevent patients developing secondary infections and, if they do, to ensure they get the best treatment.

Professor Tim WalshHead of the Edinburgh Critical Care Research Group, University of Edinburgh

Drug resistance

Infections in intensive care are usually caused by organisms that are resistant to front-line antibiotics, which are doctors’ first choice for treating infections.

Broad-spectrum antibiotics, which are more powerful, can be used as a precaution to try and prevent patients from developing an infection.

These drugs, however, can have toxic side effects. Overusing them risks breeding further drug resistance in the bacteria.

In the long term, this [test] 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.

Dr Andrew Conway MorrisIntensive Care Specialist at the Department of Medicine, University of Cambridge

Mixed results

New treatments are urgently needed but clinical trials have had mixed success.

Researchers say this is partly due to a difficulty finding patients who are at greatest risk.

Hospital study

The Immune Failure in Critical Therapy Study examined data from 138 intensive care patients from four sites across Edinburgh, Sunderland and London. Experts from the biotech company BD Bioscience helped lead the study.

The research, published in Intensive Care Medicine, was funded by Innovate UK, BD Bioscience and the National Institute of Academic Anaesthesia.

Related links

Journal article

Edinburgh Critical Care Research Group

Edinburgh Medical School