Mycobacterium abscessus is part of a group of environmental mycobacteria which are found in water, soil, and dust. Although not usually harmful to people, it can cause lung infections in people with underlying respiratory conditions.
We have been aware of mycobacterium abscessus in patients with cystic fibrosis, and other chronic lung conditions, for a decade. Between January 2016 and December 2019, we recorded 15 cases of mycobacterium abscessus infection in our cystic fibrosis patients. However, before 2019, we had not identified the organism in any of our post-lung transplant patients.
Globally, there is very little understanding of what causes mycobacterium abscessus infection, what can be done to reduce the risk to vulnerable people and how it can be treated. Some of our clinicians at Royal Papworth Hospital are at the forefront of research into the disease.
In the summer of 2019, we became concerned about a small number of our lung transplant patients testing positive for Mycobacterium abscessus infection. We have carried out extensive investigations and, although we cannot be sure, we believe our water supply could be a credible source of the bacteria.
We continue to work with partners to better understand the disease and reduce the risk to patients. We hope that sharing what we have learnt so far will also help other healthcare professionals trying to respond to this relatively new disease.
Testing our water for mycobacterium abscessus
In May 2019, we moved into our new hospital on the Cambridge Biomedical Campus.
Water safety prior to occupying a new hospital premises is regulated by a healthcare technical memorandum issued by the Department of Health and Social Care. In line with this memorandum, we were required to develop a water safety plan which included specific water testing requirements before moving into our new hospital in May 2019.
In December 2018, the results from this testing indicated that the water system of the new hospital had high counts of Legionella and Pseudomonas across the site.
In response, we took a number of actions:
- We implemented our water system remedial action plan
- We installed a hypochlorous dosing system as a secondary control measure
- We removed taps and pipework across the site, and replaced thermostatic mixing valve (TMV) cartridges
- We removed and replaced pipework in 55 locations
- We increased regular water flushing
As a result of these measures we achieved a clean water system before occupying our new hospital building. This was assured by clean sampling of the water system for Legionella and Pseudomonas.
Although we are not required by law to test our water supply for mycobacteria, we chose to do so, and none of the samples tested grew Mycobacterium abscessus.
Lung transplant patients testing positive for Mycobacterium abscessus
In August 2019, we became aware of two post-lung transplant patients testing positive for Mycobacterium abscessus. As we had not seen the organism in post-lung transplant patients before, we declared an outbreak held an initial serious incident meeting in September 2019.
We immediately launched an investigation to try to identify the source of the bacteria so that it could be isolated and removed. Although we cannot prove it, we believe that our water supply could be a credible source of the bacteria.
What actions did we take?
As part of our investigation, we carried out water sampling, with initial results in November 2019 confirming high mycobacteria counts across our hospital site. The water supply in two patient bedrooms on the fourth and fifth floors of the hospital tested positive for Mycobacterium abscessus. Sampling continued between January and June 2020, with a further six locations shown to be growing Mycobacterium abscessus.
We employed a number of engineering solutions to try and reduce the level mycobacteria in our water supply.
These solutions have included:
- installing a hydrogen peroxide plant on two floors of the hospital (where patients most vulnerable to lung infection are located). Hydrogen peroxide is believed to be effective in reducing mycobacteria in water.
- fitting point-of-use filters to water outlets (including taps and showers in areas of the hospital where patients vulnerable to problems associated with mycobacterium abscessus infection are located).
Following recommendations from our clinicians in November 2019, we also installed point-of-use filters in patient rooms where vulnerable patients are located and supplied high-risk patients with bottled drinking water.
Our estates and facilities team worked together with our infection control team and water professional advisors to implement the following actions:
- Increased water flushing in high risk areas
- Installing a hydrogen peroxide dosing system to third, fourth and fifth floor risers, critical care department and incoming mains
- Ongoing mycobacteria sampling to provide an understanding of changes to mycobacteria levels in the water system, including incoming water supply risers and outlets
- Installation of incoming mains ultraviolet treatment unit
- Installation of automatic flushing to end-of-line outlets
- Installation of anti-microbial shower heads and hoses
We continue to conduct regular sampling of our water supply.
As a precaution, any patient identified as being vulnerable to the risk of mycobacteria infection is being given bottled water while in the hospital. We have also fitted taps and showers with filters in areas where vulnerable patients are managed post-opeatively.
Who is vulnerable to Mycobacterium abscessus infection?
At present, we believe the following patient groups are vulnerable to problems associated with Mycobacterium abscessus infection:
- All inpatients on the waiting list for lung transplantation and all post-lung transplant inpatients
- Patients with cystic fibrosis
- Lung defence patients
- Patients with interstitial lung diease
How many of our patients have been diagnosed with Mycobacterium abscessus infection?
Seven of our lung transplant patients, 13 of our cystic fibrosis patients and four lung defence patients have tested positive for the infection.
What is the treatment for Mycobacterium abscessus infection?
The effect of Mycobacterium abscessus infection varies greatly between individuals. Mycobacterium abscessus infection is treated by a combination of antibiotics, administered intravenously and orally. This treatment is often prescribed for a prolonged period of time.
Are current and new patients safe?
We have employed a wide range of engineering solutions to mitigate the risk posed by mycobacteria. As a precaution, we have been supplying bottled water to vulnerable patients and have fitted filters to taps and showers in certain areas of the hospital. We are conducting regular testing to monitor the effectiveness of these solutions.
We continue to work closely with partners to consider any further measures we could take to reduce the risk to vulnerable patients.
We have written to all of our patients who we believe could be vulnerable to problems associated with Mycobacterium abscessus infection. We are carrying out an enhanced consent process with our potential lung transplant recipients to ensure they are fully aware of the Mycobacterium abscessus outbreak in the hospital. Our intention is to give patients the information they need to balance the risk of this mycobacteria against the benefits of being treated here.