A group of researchers are to evaluate whether a simple blood test for bacterial infection could help to reduce the use of antibiotics in patients with Covid-19.

A procalcitonin blood test (PCT) is used in hospitals to distinguish between bacterial and viral infections and guide antibiotic treatment.

Cardiff University reports this study will investigate whether the test is effective in Covid-19 patients by looking at data from the first wave of the pandemic in UK hospitals.

Dr Emma Thomas-Jones, deputy director of the Centre for Trials Research at Cardiff University, which is coordinating the research, said “COVID-19 is caused by the SARS-CoV-2 virus, therefore antibacterial agents – antibiotics – have no direct effect. On top of this, published data indicates that rates of secondary bacterial infection are low in COVID-19 patients, so antibiotic use early in the course of the disease may be unnecessary.

“Despite this many patients are being prescribed antibiotics empirically because of concerns that they may have secondary bacterial infections.

“The COVID-19 pandemic has potential to drive an increase in antibiotic use at a time when antimicrobial resistance is an increasing threat to global health. It’s important to look closely at our use of antibiotics in every scenario to help tackle this issue.

“The COVID-19 pandemic has potential to drive an increase in antibiotic use at a time when antimicrobial resistance is an increasing threat to global health. It’s important to look closely at our use of antibiotics in every scenario to help tackle this issue.”

Procalcitonin is a marker of infection that can be measured through a quick blood sample.

The researchers will analyse retrospective data from seven thousand Covid-19 patients across eleven NHS acute hospitals, half who will have used PCT testing during first wave of the pandemic, to determine whether and how PCT testing should be used to protect patients from antibiotic overuse if the NHS experiences a second wave.

They aim to find out if use of the test in Covid-19 patients reduced antibiotics and/or improved patient outcomes, such as time in hospital or in intensive care, death rates, and infections with superbugs, and will also assess its cost effectiveness.

They will produce guidelines for doctors on how best to use the test in patients with Covid-19, so that antibiotics are started early if needed and stopped promptly if unnecessary, thus reducing side effects, antibiotic resistance and infections with superbugs.

Professor Philip Howard, President of the British Society of Antimicrobial Chemotherapy and member of the National Institute for Health and Care Excellence COVID-19 rapid guideline on antibiotics, said “Almost three-quarters of patients admitted with suspected or proven COVID-19 pneumonia get antibiotics for this viral infection while less than 1% have a bacterial co-infection.

“The inappropriate use of antibiotics drives antimicrobial resistance so I’m really pleased that the NIHR has commissioned this important research.”

Patient representative Margaret Ogden said “I’m keen to see minimal use of antibiotics and only when needed. This study is a step forward in clinical decisions in antibiotic prescribing and should be of benefit to patients and, by extension, their carers and family members.”

The Procalcitonin: Evaluation of Antibiotic use in COVID-19 Hospitalised Patients (PEACH) study is a collaboration between Cardiff University, the University of Leeds and the University of Liverpool. It will last for eighteen months and has received £730,000 in funding from the National Institute of Health Research (NIHR).

It is one of a number of Covid-19 studies funded by the NIHR as part of its Recovery and Learning call, totalling £5.5m in funding, to help better manage current and future waves of the Covid-19 pandemic and investigate its long-term impacts on the health and care system beyond the acute phase.

Chief investigator Dr Jonathan Sandoe, from the University of Leeds School of Medicine, said “This important project aims to reduce the harm done by unnecessary use of antibiotics in patients admitted to hospital with COVID-19. We are very pleased to receive NIHR funding for this valuable study.”

The Centre for Trials Research is publicly funded by Health and Care Research Wales and Cancer Research UK.