Exploring phage therapy to treat lung infections

Over the last few years there has been renewed interest in the Western world in developing bacteriophage treatments for infections. They are being explored as a treatment for cystic fibrosis (CF) lung infections in a range of different ways. Here we explain more about what phages are, the different ways that they could be used as a treatment and how the Trust is supporting their development.

Below, we’ve listed some of the questions you may have about bacteriophages and why we’re researching them in CF.

What are bacteriophages?

Also known as ‘phages’, bacteriophages are naturally occurring viruses which infect bacteria instead of human cells. They kill bacteria when they infect them. They are very specific about which bacteria they infect, sometimes only infecting a specific variant of an infection-causing bacteria.
Why is there interest in phage therapy?

Phage therapy could become another option to treat CF lung infections. In addition, as they are so specific, researchers hope that using phages as a therapy can reduce the side effects seen with antibiotics – both in terms of not attacking ‘good bacteria’ in the lungs and elsewhere, and also having less toxicity in other parts of the body.
How could phage therapy be useful in CF?

Researchers hope phage therapy can be used as a treatment for long term CF lung infections, particularly where antibiotic options have become very limited due to antimicrobial resistance (AMR) or side effects. Phage therapies could be used alongside antibiotics to reduce the amount of antibiotics given, or phage therapies could be used on their own.
Reducing the amounts of antibiotics when antibiotics and phage therapy are used together could reduce their side effects. Using them together an also reduce AMR.
Antimicrobial resistance (AMR) refers to the way bacterial, viral and fungal infections have adapted to defend themselves against antimicrobial medicines (eg antibiotics), making them ineffective.
Ideally, in the future phage therapy may also be considered as a treatment to clear early infections from the lungs.
When might phage therapy be available for people with CF

Phage therapies are being developed that could be used as treatments for specific infection-causing bugs. Some of these may start to be tested in clinical trials in the next few years.
Occasionally, personalised phage therapies are developed for individuals with CF for hard-to-treat infections. Each one can take more than a year to develop – for more information see the section on ‘True or false – you can get phage treatments in the UK’ on the ‘Exploring more about phage therapy’ webpage.
Why is more research into phage therapy needed?

Scientists need to find the phages that are available in nature and test and sometimes adapt them in the lab. For example, to check if they produce toxins, or to make the phages more specific for the infection-causing bacteria.
Next, more detailed and extensive tests are carried out to develop them into a treatment, for example to make phages effective and safe to deliver them into the lungs of people with CF, working out how many phages to give and when, and how to make enough ‘medical-grade’ phages to use in these treatments.
How is Cystic Fibrosis Trust involved in research into phages?

Making access to phage therapy clearer and easier - Trailfinder-CF Innovation Hub
One of the aims of the Trailfinder-CF Innovation Hub is to develop new and more tailored treatment approaches for CF lung infections, by developing phage therapy. It’s led by Professor Jo Fothergill, from the University of Liverpool.
“At the moment phage therapy is only used as a last resort. We want to change that, particularly for people with chronic lung infections, making access easier and clearer for doctors and people with CF,” explained Professor Fothergill.
The Trailfinder-CF Innovation Hub is part of the Translational Innovation Hub Network for CF Lung Health and Infection funded by the Trust and LifeArc.
Learn more about the Trailfinder-CF Innovation Hub
Finding phages to treat Burkholderia cepacia complex infections
Trust-funded researchers in Cardiff University and University of Leicester are combining their strengths to look for phages that could be used in treatments for the Burkholderia cepacia complex group of bacteria. Their research studies include finding phages that could work as a potential treatments, testing and improving them in the lab and preparing for the production of phage therapies.
Find out more
Guidelines to accelerate development of phage therapy
Researchers within the Trailfinder-CF Innovation Hub have joined forces with colleagues in the CF AMR Syndicate to deliver a set of guidelines for the development of phage therapies to treat lung infections in CF. These guidelines known as Target Product Profiles (or TPPs for short) have been informed by the experiences and insights of people living with CF.
Learn more about the patient-focussed phage therapies TPPs
Supporting phage therapy clinical trials

Please see our Trials Tracker for information about any phage therapy clinical trials being planned in the UK.
Visit our Trials Tracker

Find out more:

CF LIVE on phage therapy

Listen to a panel of experts explaining what phage are, how phage therapy may be used to treat lung infections in people with CF and talking about gaining access to phage, plus Q&A from the audience in an event recorded in June 2025.

Find out more

The Trailfinder-CF Innovation Hub research programme

The Trailfinder-CF Innovation Hub website contains helpful explanations about phages and phage therapy aswell as how people with CF and their families can get involved in their research programme.

Visit the research programme website

Read our summary on the Trailfinder-CF Innovation Hub