Discovering a new home diagnostic tool to detect Pseudomonas aeruginosa

Feature -

Sarah Sharp, a person with CF and guest editor of the June CF News, interviews Dr Shaun Robertson and Professor Miguel Cámara, researchers of a new home diagnostic tool for Pseudomonas aeruginosa.

Dr Shaun Robertson(right) and Professor Miguel Cámara (left)While working with Cystic Fibrosis Trust to guest edit the June issue of CF News, I had the privilege of speaking with Dr Shaun Robertson and Professor Miguel Cámara, researchers working on a very exciting new diagnostic tool for Pseudomonas aeruginosa

As someone who was first diagnosed with Pseudomonas aeruginosa at six months old and has had it as a constant companion ever since, I was particularly intrigued by this research. 

Facilitated by the Trust, I spoke to Shaun and Miguel over Teams. You can read our conversation below.

Hi Shaun and Miguel. Can you tell me about how you started working on Pseudomonas?

Miguel: We’ve been working on the bacterium Pseudomonas aeruginosa for more than 30 years now. It is responsible for many hospital-acquired infections and is highly resistant to antimicrobials. Originally, we were interested to discover new ways to target Pseudomonas aeruginosa infections.

One of the areas we’ve been interested in is how individual Pseudomonas bacterial cells have developed a way to communicate with other Pseudomonas cells by producing ‘quorum sensing’ chemical signals. This helps them all respond to changes in the environment in a coordinated manner.

When did it occur to you that you could create a diagnostic tool?

Miguel: The whole thing started because we wanted to know whether there was evidence that Pseudomonas aeruginosa produced these quorum sensing chemicals in the lungs of people with CF with Pseudomonas infection.

So, we embarked in a big clinical trial and obtained samples from more than 400 people, taking samples of sputum, saliva, blood and urine. We really did not expect to detect what we were looking for anywhere but sputum, but we did! And that meant we could look for the presence of the quorum sensing chemicals as a biomarker of infection. 

We were also given samples from people with CF that were having an exacerbation, and samples after their antibiotic treatment. To our surprise, the level of quorum sensing chemicals went down very quickly with treatment.

After discovering that, we knew we could then use the detection of the quorum sensing chemicals in people with CF to establish whether treatment was working.

From there we moved this forward, developing a way to detect the quorum sensing chemicals using antibodies.

Your diagnostic tool is a lateral flow test, a technology which has become almost common objects in homes as well as hospitals with the recent pandemic. So, for those of us looking forward to the test kit being a reality, can you briefly explain how the test will work?

Shaun: The test will be a lateral flow test, and we’re still designing it at the moment. Lateral flow technology was used in COVID-19 tests during the pandemic. We’ve been looking at developing a lateral flow using blood samples, rather than throat or nose swabs used in the COVID tests. If this works, it could be like a finger prick that then goes on to the lateral flow.

There will be other key differences to the COVID-19 tests for people to know too. With a COVID-19 test, when you got the line that meant a positive result. Ours will work the other way round. When you have a line it means [Pseudomonas] is not there, whereas no line means it is there. It is also designed to tell us the levels of Pseudomonas infection present.

If you’re doing it at home people will use a smartphone app to read the result and send it to the clinical team. The app reader will measure the amount of Pseudomonas present and help to keep the tests as accurate as possible.

We hope that people that have established Pseudomonas will be able to use the test to monitor when they are potentially getting an exacerbation and then be able to get treatment earlier before that exacerbation happens. 

Why is diagnosing Pseudomonas aeruginosa early really important?

Shaun: The aim of our test is to prevent Pseudomonas infection becoming established in the lungs and limit the damage as much as possible in those who have long term infections.

One of the main drivers in the last 10 years has been about detecting initial pseudomonas infections as quickly as possible, through sputum culture. But sputum is now difficult for some people on Kaftrio to produce and alternatives are needed.

Essentially, we know that if we detect Pseudomonas and start treatment quickly, the better the outcome of preventing long term infections. And that’s really important because there are so many quality-of-life and length-of-life effects of developing long term Pseudomonas infection.

There are economic benefits of developing an early test for Pseudomonas infection too, as it could reduce the numbers and cost of hospital beds required, and the wider impact on the economy as well, not to mention that financial impact on people with CF.

For people that are chronically infected, we want to detect their exacerbations earlier. And if we treat them early, we can limit any possible lung damage.

You said this is all still in development, but how far in the future do you think those of us with CF will be using these tests at home or in clinic?

Shaun: We have to go through all the regulatory approvals if we want people with CF to use our tests at home. So, for now we are looking at transferring this into the clinic setting.

Ideally, we’d be looking at trying to get this into clinics and for limited use first in Nottingham where we have very strong links with the CF centre. When we’re looking at the regulatory approval and the time it takes to get that done, you’re probably looking at mid-2026. So not too far away. 

How has the Trust supported your research and what does this charity mean to you?

Miguel: The Trust have been instrumental. From the early points when we thought the possibility of developing a test existed, I contacted the Trust and said: ‘I’ve got some funding, but it’s not enough to be able to develop antibodies needed for the test, would you be interested in giving us funding for it?’. And they immediately gave me funds with the Trust’s Venture and Innovation Award. We’ve kept the Trust engaged all the way through and they have been extremely supportive.

Shaun: I met Lorna Allen from the Trust’s Involvement Team at the ECFS Conference two years ago. Through that we were able to talk and instantly she set up focus groups with people with CF. We wouldn’t be where we are without the Trust. 

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