With input from the Trust’s associate director of Engineering, Louise Clark, Nigel Otter, Marketing manager EMEA at IDEXX, discusses Guy’s and St Thomas’ NHS Foundation Trust’s successful use of two of the company’s rapid microbiology systems to test for, and identify, Legionella and Pseudomonas aeruginosa, ‘in-house’, in the water systems of its two largest London hospitals. Using this testing technology has enabled the Trust to implement, and confirm the impact of, remedial actions in the shortest possible timeframe.
Healthcare estates and facilities managers must be alert to the dangers of waterborne bacterial contamination, as it has the potential to lead to serious infections, especially among immunocompromised patients, such as the elderly, people undergoing treatment for cancer, people in burns units, or premature infants. Rapid, accurate, and regular testing of water systems for bacteria such as Pseudomonas aeruginosa and Legionella is vital to ensure that any contamination is detected as early as possible, so that remedial action can be initiated before any risk to patient safety arises
Louise Clark, associate director of Engineering at Essentia, part of Guy’s and St Thomas’ NHS Foundation Trust, in London, explained: “Water services are there to support clinical care, and it is therefore imperative that outlets remain in use. Across our estate, we have 10,000 thermostatic mixing valves (TMVs) and approaching 18,000 outlets. So, as a Facilities manager, if you are coordinating the response to a Legionella or Pseudomonas problem, you cannot afford to waste any unnecessary time before determining the appropriate steps of remedial action.”
In-house testing
“A few years ago, at Guy’s and St Thomas’,” she continued, “we had a problem with the water system in a number of areas of the organisation. At the time, we were using a specialised water contractor to undertake the testing. This was time-consuming and potentially risky, as it allowed issues to remain within the system for a longer period, and possibly to develop while we waited for the results. This led to the deployment of many point-of-use filters, and to us taking some outlets out of use, which presented a problem in itself, as they would be declared ‘little-used outlets’, having the potential to grow bacteria and become deadlegs. We wanted to speed up the process of returning these outlets back to normal use.”
The Trust turned to IDEXX, a manufacturer of rapid water microbiology testing methods. Louise Clark, and her director of Engineering, had previously used these the company’s systems, including Pseudalert. Psdeudalert is used as a method to enumerate Pseudomonas aeruginosa bacteria in water under the ISO international standard for 24-hour detection of Pseudomonas aeruginosa in water (ISO 16266-2:2018). Samples can be processed in less than one minute, and the results are available the next day without additional confirmation steps, with interpretation of results achieved through observable fluorescence after incubation.
Speed of results
A trial was run with Pseudalert to demonstrate the speed at which results could be delivered. “We were able to get quicker confirmation of the effectiveness of our remedial actions,” explained Louise Clark. “IDEXX kindly lent us some kits and trained the staff in their use, and within five to six weeks we had approved the equipment and purchased systems for both sites.”
She added: “Using the IDEXX tests puts us in control of the whole process, and we can ensure that each stage is conducted correctly, unlike when external contractors are used, and there are concerns as to whether samples are being taken correctly, and maintained within the correct temperature range throughout the transit stages – from sample point to laboratory
“When we undertake the testing inhouse, we can control the samples from the point at which they are taken to the point at which they are read – ensuring that all the correct parameters are followed throughout the process, and receive confirmed results within a 24-hour period. In contrast, it might take up to a week using contractors and an external lab.”
Advantages of rapid, in-house testing for Guy’s and St Thomas’
With the vast number of outlets, and potential sites for contamination, the Trust uses IDEXX tests on a regular basis to monitor its water system. Louise Clark explained: “We have found that the use of IDEXX Water’s testing methods significantly helps reduce any downtime encountered with problematic outlets. The simple tests are fast, cost-effective, and put us in control.
“When we have a particular issue, we use the IDEXX tests to identify and locate the problem, and to get a speedy resolution. The kits quickly determine the conditions in the water system for bacterial growth, and indicate whether we have eliminated them with our remedial actions. This means that the outlets can then be returned to use quickly and more cost-effectively.”
“Some of my colleagues were initially sceptical,” Louise Clark continued, “but they have been won over, and are now more readily accepting of the methods, and the results they deliver. The clinical staff and infection prevention and control teams are supportive of the rapid results of in-house testing.
“Recognising that there is a requirement for continual monitoring and testing, we will continue using these rapid technologies to support and understand the extent and impact of any contamination, and of our remedial actions. Taking this into account, we have amended our standard operating procedures in the Trust to include the use of IDEXX rapid testing methods alongside accredited procedures.
Challenges during the COVID-19 pandemic
Faced with a potentially major Legionella issue at the height of the COVID-19 pandemic, and challenges in coordinating external contractors to sample and test water, the Trust again turned to IDEXX for assistance.
The Facilities team had introduced enhanced flushing procedures throughout the estate wherever lower utilisation had been identified. However, one particular instance of lower usage was not brought to the attention of the team. This concerned two lower floors of a nonpatient area in one building, which saw a reduction in outlet use when staffing levels reduced. Subsequent monthly routine testing of the area showed positive results for Legionella.
While the UKAS-accredited tests take up to two weeks to confirm the presence of Legionella, through the relationship with IDEXX, and the routine use of, and confidence in, the previously proven Pseudalert method, the Trust trialled the use of the IDEXX Legiolert test to see if the problems could be identified and resolved more effectively.
IDEXX launched Legiolert in Europe and North America in 2017. It is a liquid culture method using most probable number (MPN) that is highly sensitive for the confirmed detection of Legionella pneumophila (the primary cause of Legionnaires’ disease) in water. The Legiolert method is certified by AFNOR ‘NF validation’ (IDX 33/06-06/19), and has been published by ASTM International as the ASTM D8429-21: Standard Test Method for Legionella pneumophila in Water Samples Using Legiolert. The method delivers confirmed results within seven days, which can be twice as fast as the conventional plate culture testing methods and, as with Pseudalert, samples can be processed typically within one minute, with the presence of contamination indicated by a colour change of the sample after incubation.
The extent of the contamination
“As the person responsible, I needed to know what action was required,” said Louise Clark. “We began with a small area. As we investigated back, we increased the area, supporting the UKAS-accredited testing with extensive Legiolert testing. We had a concern about the extent of the contamination, so we took an initial batch of over 120 additional samples one Friday morning, which were couriered immediately to IDEXX’s laboratory, which ran the tests for us. IDEXX was very supportive, and the speed of the method meant that we had preliminary results early the following week. This gave us a much clearer view of the extent of any potential issues.”
The samples were run alongside UKAS-accredited testing to determine whether there was correlation between the results. The comparison was very favourable, which allowed Louise Clark’s team to quickly pinpoint contamination issues, undertake rapid remedial actions, and check how effective they had been.
Legiolert system
After this initial batch, the Trust installed an in-house Legiolert testing system to support the processing and incubation of the high volume of samples required. Louise Clark said: “This was all in an attempt to reduce the timescale that was faced to take remedial action. It allowed further interventions to be deployed where necessary, much earlier than would normally be the case.”
Leading water hygiene specialist, Dr Paul McDermott, provided technical support to the Trust on COVID-19-related contingency projects involving water-critical areas. He said: “When testing routinely in hospitals, you will sometimes find Legionella. Usually, it does not result in an infection, but finding the bacterium in hospital water systems should always result in some form of internal investigation, and in some hospital areas its presence is particularly significant.
“Positive test results can mean that part of a water system is taken out of use temporarily, and, like everything else, this has a resulting cost – even if a single tap is taken out of use, there’s an associated cost. UKAS-accredited laboratories will not release final results until they are confirmed, according to ISO 11731, and although some labs will give preliminary results, these can be misleading, as colonies may appear on plates later in the incubation. Legiolert provides confirmed results within seven days, so offers much greater certainty of knowing if the samples you had taken were negative for the bacterium, or at least having a clearer understanding of what the problem might be.”
Ongoing testing to ensure patient safety
As well as the ongoing in-house testing using Pseudalert, the Trust’s use of Legiolert as a monitoring tool continues. Louise Clark explained: “Having longterm experience with Pseudalert, and the positive trials with Legiolert, the upshot is that we have reviewed our internal arrangements and procedures, and recognised that there is a requirement for continual monitoring and testing. We will continue using the IDEXX rapid testing systems in supporting and understanding the extent and impact of any contamination and remedial actions.
“The design of the building, and the difficulty in accessing all of the water services within it, means that we have occasional unpredictable flare-ups, so we use the IDEXX methods to support the remedial actions taken. Again, some of my colleagues were initially quite sceptical, but are now more readily accepting of the Legiolert process and the results that it delivers.
“We use Legiolert to support the testing for Legionella that is also undertaken for us by UKAS-accredited laboratories, as advised in guidance,” Louise Clark explained. “This is not currently the case for Pseudomonas aeruginosa, where guidance does not specify testing by a UKAS-accredited laboratory. While the Trust’s use of Legiolert is not UKASaccredited, IDEXX provides us with external quality assessment samples, which gives us the assurance that our inhouse testing is accurate
The people and the whole system
“We appreciate that UKAS accreditation covers more than simply the test. It is also about the laboratory, the people – the whole system. However, we believe that the system we have adopted, which uses testing conducted in UKAS-accredited labs supported by our own in-house testing, gives us real advantages in the way we test for the bacteria, and what we do when we find them.”
Louise Clark’s team includes Water manager, Jonathan Danso, and Engineering team leader, Daryl Merrylees, Both use the IDEXX methods routinely, and see the benefits of in-house testing to patient safety. Jonathan Danso explained: “If we have an area of low usage, we can use Legiolert to monitor the outlets and keep costs down. Where the count is high, it gives an early indication, enabling us to take remedial action quicker. The IDEXX process gives reassurance to clinical staff that there is not an issue.”
Faster identification and money saved
For Daryl Merrylees, the rapid results show the benefits of the tests. He said: “If we have suspected Legionella contamination, to remove point-of-use-filters we have to get three clear results. The UKASaccredited tests need 14 days to get results, so the three tests required take at least six weeks. With Legiolert we can get an early indication at seven days of any bacterial growth. The IDEXX methods speed everything up and save money, as we take the samples and process them in-house.”
Louise Clark concluded: “Hospitals are there to make people better, rather than to give them another infection. Therefore, should there be a risk of Pseudomonas aeruginosa or Legionella pneumophila, the way we monitor and test our systems in-house with the support of IDEXX methodology is really useful. Using this testing technology allows us to implement and confirm remedial actions in the shortest possible timeframe, minimising any impact on patient care.”
Nigel Otter
Nigel Otter graduated from the University of Newcastle upon Tyne with a Life Sciences degree, and has spent the majority of his career working in the pharmaceutical, biotechnology, and diagnostics industries. He has worked in a variety of senior executive roles both in the UK and internationally, predominantly in marketing, managing brands and teams, and pioneering new lifesciences technologies in established markets.
He joined IDEXX Water, a specialist company dedicated to water microbiology, in 2013, as Marketing manager EMEA. In this role, he has been involved in the launch of innovative rapid microbiology diagnostic methods for the detection of Pseudomonas aeruginosa, Legionella pneumophila, SARS-Cov-2, and heterotrophic bacteria in water. In addition, as part of the IDEXX EMEA team, he manages the company’s core product lines for the detection of coliforms and E.coli in drinking water, used to monitor and protect water quality for 2.5 billion people globally. Today he is focused on the adoption of in-house water microbiology testing by hospitals on behalf of IDEXX Water.