In 2019, following some routine testing, we launched an investigation into some cases of Mycobacterium abscessus infection, a rare infection which can cause problems for people with specific underlying respiratory conditions or who are immunosuppressed as a result of their condition.
Here you can read about what we found, what we did, and how we’re monitoring and managing the situation.
What is Mycobacterium abscessus?
Mycobacterium abscessus is one species of a group of bacteria (Mycobacteria) commonly found in water, soil, and dust. It can enter people’s lungs and other organs naturally through exposure in the environment, and although it is not usually harmful to the general population, it can cause lung infections in some people who already have specific underlying respiratory conditions or who are immunosuppressed as a result of their condition.
Treatment is not always needed but can be a combination of antibiotics, administered intravenously (through a vein) and orally (swallowed). This treatment may be prescribed for a prolonged period of time.
These types of bacteria have been seen in a growing number of people with cystic fibrosis across the world since the 1990s, so it’s been normal practice for many years for us at Royal Papworth Hospital to regularly test for it as part of our ‘business as usual’ in patient care.
Our investigation
In August 2019, after we had moved to our new hospital on the Cambridge Biomedical Campus, it was confirmed that two of our post-lung transplant patients had tested positive in our routine testing for Mycobacterium abscessus. We hadn’t seen this before in our post-lung transplant patients, so we launched an investigation to find out more and ensure the safety of our patients.
These investigations were, and remain, extensive and it was confirmed we had found these bacteria in our water supply.
Immediate action
We took immediate action, including putting in enhanced ‘point of use’ (POU) filters on water outlets (basin taps and showers), providing bottled water to our most susceptible patients, and doing extra environmental testing and taking more water samples. We installed a dosing plant (called a hydrogen peroxide dosing plant) and an ultra-violet treatment unit on site to minimise the number of bacteria in the water. .
Through our regular testing, we know that these measures have been effective in reducing the counts of mycobacteria at the Trust. We have never grown M. abscessus from a water outlet with a POU filter on it and we continue to test regularly as part of our ongoing investigations.
We are working alongside water specialist advisors, as well as other health agencies to analyse all potential modes of transmission. Clinicians at Royal Papworth Hospital are at the forefront of research into the disease and we are happy to share our findings and learning with any other organisation that may benefit - please contact us if you’d like to discuss this.
We’ve made sure to keep all our regulators fully informed throughout the investigation process, and have involved water safety and public health experts from the beginning.
If you have questions, please ask
If you are a patient coming in for treatment with us and your clinician thinks you might be particularly susceptible to Mycobacterium abscessus, you will be informed. You can then have a conversation with your clinical team to ask any questions you might have.
The patients we consider most susceptible to Mycobacterium abscessus are:
• Pre and post-transplant inpatients
• People with cystic fibrosis
• Lung defence patients
• Patients with interstitial lung disease.
If you are a potential lung transplant recipient, we will talk through our enhanced consent process with you so that you’re fully aware of the issue, any potential risks, and how we are managing the situation.
If you have any concerns, please contact your clinical team who will be happy to support you.
You can read more about Mycobacterium abscessus, and our ongoing response to how we’re managing it, below.
When did we find out about this problem?
Mycobacterium abscessus is not usually harmful to the general population but is known to affect people with specific underlying respiratory conditions. Infection with non tuberculous mycobacteria including M abscessus have been seen in a growing number of people with cystic fibrosis since the 1990s through everyday exposure to things like water, soil and air.
It has therefore been our normal process for many years to test certain patients (mainly cystic fibrosis patients) for the bacteria and support with treatment if they need it. It is not unusual to find positive cases amongst this patient group as infections can happen through ordinary exposure in the general environment - as an example, between January 2016 and December 2019 while we were at our old hospital site, we recorded 15 cases of Mycobacterium abscessus infection in our cystic fibrosis patients. With this in mind, when moving to the new site we invested in a state-of-the-art ventilation system in our cystic fibrosis treatment areas so that we were using all available best practice to reduce any chance of hospital acquisition.
In August 2019, two of our post-lung transplant patients tested positive for Mycobacterium abscessus infection. This was the first time we had identified the infection in a post-lung transplant patient, although from our subsequent investigation we understand there have been similar cases in other transplant centres, especially in the USA.
To ensure our patients’ safety, we immediately launched an investigation to find out more – in the NHS this is called a serious incident (SI) investigation.
As part of our investigation we carried out water sampling, and in November 2019 it was confirmed we had found these bacteria in our water supply.
What have we done in response?
We have put multiple measures in place to enhance the treatment of the water supply, which include:
- Installing a hydrogen peroxide dosing plant.
- Fitting point-of-use filters to water outlets.
- Supplying bottled drinking water to patients who are more susceptible.
- Increasing water flushing in high risk areas.
- Conducting ongoing mycobacteria sampling (including water, surface and air sampling) so we can quickly see any changes in mycobacteria levels in the water system, including incoming water supply risers and outlets.
- Installing an ultraviolet treatment unit.
- Installing automatic flushing to end-of-line outlets.
- Installing anti-microbial shower heads and hoses.
Collectively these actions have reduced the counts of mycobacteria at the Trust.
We have never grown M. abscessus from a water outlet with a POU filter on it.
We continue to conduct regular and enhanced sampling of our water supply.
We will continue to work alongside water specialist advisors in our ongoing management of the investigation and share our learnings.
Was the water safety checked before the new hospital opened?
Yes it was.
Water safety in UK healthcare is regulated by a healthcare technical memorandum (HTM) issued by the Department of Health and Social Care. This also regulates water safety before a hospital premises can be occupied.
Before moving to the new hospital in May 2019 we developed a water safety plan, which included specific water testing requirements in line with the above regulations.
This also meant taking specific measures to ensure we had a clean and safe water system, including: putting in a sodium hypochlorus dosing system as a secondary control measure; taps and pipework across the site were removed and thermostatic mixing valve (TMV) cartridges were replaced; pipework across 55 locations was removed and replaced; and water flushing was increased.
Following the implementation of various measures, the water supply was deemed clean and safe and the hospital was approved for occupation in May 2019.
How many patients have acquired Mycobacterium abscessus infection?
Since implementing our stringent and additional water safety measures, we have significantly reduced the counts of mycobacteria at the Trust.
Since moving to our new hospital in May 2019, 67* patients have been confirmed positive for Mycobacterium abscessus through our testing.
Mycobacterium abscessus positive sputum (mucus from the lungs) tests are not unusual in certain patient groups as it can be contracted in the community. Therefore we undertake genome sequencing on all cases to identify if they are linked to our water supply.
It is likely 39* cases are related to the outbreak (this means the bacteria has likely come from the same source). Many patients have not needed treatment to date, and several have tested negative after one positive result.
We continue to regularly test and monitor the effectiveness of the measures we have put in place at the Trust. We are continuing to work closely with partners like the UK Health Security Agency (formally Public Health England) to ensure all recommended response measures are implemented at the Trust.
*These figures were last updated in June 2025.