The NHS and its building infrastructure are undoubtedly facing challenges that could impact the health of vulnerable patients, but there is another risk which could add to these if not taken seriously – Legionella. Legionella is a waterborne bacterium that lives in the natural environment, but generally only becomes a major risk to human life when it enters the built environment. It can cause a severe form of pneumonia called Legionnaires’ disease, which can be deadly. Legionella is a rapidly multiplying bacteria that can – even if small amounts are present – infect a complete water system in no time. Legionella doubles every 24 hours.1 The hospital environment should be considered as a serious risk area for Legionella due to the large number of vulnerable and/or immunocompromised patients, in addition to 37% of A&E attendances and 63% of admitted patients in England alone falling within the higherrisk ages category (50+).2
The NHS, as one of the largest and most complex healthcare systems in the world, provides care to more than 67 million people in the UK. Over the years, this system has faced several challenges, including funding shortages, staff shortages, and rising demand for healthcare services. One of the most pressing challenges, however, is the outdated infrastructure of many NHS hospitals. A recent investigation conducted by ITV News highlighted the poor state of some, and particularly ageing, NHS buildings – from year-long leaks and collapsing floors, to ageing roofs and the potential for falling brickwork, and the risks these pose to the health and safety of patients and staff alike.3
Unresolved structural or maintenance issues
Alarmingly, 50% of the responding hospital Trusts in England highlighted that as of October 2022 they had at least one unresolved structural or maintenance issue. The Walton Centre NHS Foundation Trust in Liverpool, for example, has suffered an ongoing stairwell leak for eight years; a leak at Lewisham and Greenwich NHS Trust has been left for nearly two years, and a leaking roof at University Hospital Southampton NHS Foundation Trust has remained for nearly 18 months so far. With some hospitals dating back as far as the 1930s, their walls and ceilings are crumbling and collapsing. Doctors fear that these environments are not fit for the purpose of patient care.
To address this problem, the Government has committed to investing over £3.7 bn in the construction of new hospitals across the country. This funding will also be used to refurbish existing hospitals, upgrade facilities, and provide state-of-the-art equipment and technology. The aim is to improve patient outcomes, increase capacity, and create a more modern and efficient healthcare system.
Reports of delays
There are already reports of delays to this ambitious face-fit and construction programme, however, and government critics argue that this funding is not sufficient to address the scale of the problem. A focus on new, leading-edge hospitals and facilities could be ignoring the significant needs of the existing estate. That said, a commitment to investment in NHS hospital construction is a significant and much-needed step forward for the UK healthcare system. Even so, however, a programme of this scale will take many years to undertake, so the reality of the here and now needs to be the focus. With respect to the risks posed by Legionella bacteria in these existing buildings, there are several areas of concern which should be considered
Ageing pipework – complicated and ageing pipework with deadlegs poses a real threat, as it provides ideal conditions for the formation of rust, scale, sludge, and amoeba, which provide nutrients, and support rapid Legionella growth and spread
Leaks and flooding – any standing water can become stagnant; this could be hidden in cavities, broken tiling, and in dips of uneven flooring. This water could harbour Legionella bacteria long after the visible flood has subsided. In addition, puddles in hightraffic areas, where perhaps trolleys are wheeled through, could launch Legionella-contaminated aerosols into the air, where they can be inhaled by the unsuspecting vulnerable
Unused facilities in closed wards – any water outlet that is used either infrequently, or not at all, is a serious risk for Legionella growth, as this too creates stagnation. Closing wards due to structural risks, and then being forced to use them again – because of overcrowding – would put patients at risk of infection unless these environments have been recommissioned correctly
On-site construction projects – during construction work, the plumbing systems of a building can be disrupted or disconnected, and sections may be temporarily taken out of service, leading to stagnant water becoming trapped in pipes and fixtures. This stagnant water can then provide an ideal breeding ground for Legionella bacteria. Additionally, construction activities such as drilling and cutting can create dust and debris, which can contaminate water systems and encourage biofilm (slimy communities of sessile microorganisms including bacteria, algae, and protozoa) to develop on the inside of pipes. The majority of Legionella, if present, will reside within this biofilm, which can also provide ideal nutrients for Legionella growth. When the water system is then put back into service, this contaminated water can be dispersed throughout the building, leading to potential exposure of patients and staff to the bacteria
Cooling towers maintenance that are out of compliance – because of their ability to spread Legionella over a wide area, cooling towers are regarded as one of the most dangerous and heavily regulated sectors in the water treatment and Legionella control industry. The aim of these systems is to extract heat from a building and dissipate it into the atmosphere via an evaporative process. The heat and evaporated water then flow out the top of the tower in the form of a fine cloud-like mist. If windows are open to give patients some much-needed fresh air, they could be unknowingly breathing in Legionellacontaminated aerosols. A study was conducted by the CDC (Centers for Disease Control and Prevention) after a significant Legionnaires’ disease outbreak caused by cooling towers in the US in 2015. Legionella species DNA was found in 88.5%4 of the cooling towers tested, and specifically Legionella pneumophila DNA was detected in nearly 50%. Therefore, the maintenance of these systems is essential.
Legionella pneumophila is the species responsible for approximately 90% of Legionnaires’ disease cases.5 L. pneumophila is divided into 15 serogroups. and serogroup 1 is proven to be the most prevalent disease-causing variant. In fact, the ECDC (European Centre for Disease Prevention and Control) Annual Epidemiological Report for 2020 highlighted that Legionella pneumophila serogroup 1 was the cause of 83% of cases reported between 2019 and 2020 alone.5
A greater focus on Legionella hazards needed
Care-giving buildings that are falling apart need to be a focus for the government, and that focus needs to be wider than just the immediate risk from falling debris or mould. The focus should include the hazards of waterborne pathogens, especially Legionella pneumophila, which is triggered by this very state of disrepair. While a refurbishment and construction programme could reduce the risk of Legionella in the long term, there are many well-known specific Legionella risks associated with this
Several phases of a construction project can increase the risk of Legionella proliferation. These include excavation, inadequate building water system recommissioning, construction equipment with water reservoirs, re-pressurisation, demolition activities, underground utility connections. and water main breaks. Alarmingly, in a report by the International Journal of Environmental Research and Public Health, more than three-quarters of Legionnaires’ disease cases linked to construction activities were found to be in healthcare buildings.6 An overwhelming 71% of these healthcare settings involved acute care hospital operations.
Construction activity risks
In the same report, the top construction activity contributing to Legionnaires’ disease cases by frequency of occurrence was excavation (38.7%).6 The physical process of excavation can cause bacteria like Legionella to become airborne, which can compromise water reservoirs and enter the mechanical water system, ultimately negatively affecting the water quality. Excavation is also responsible for a case fatality rate (CFR) of 11.8%,6 only being topped by ‘commissioning’, at 14.4%. Both figures are higher than the accepted community-acquired CFR of 10%, so it is clear to see that excavation increases the death risk significantly. Add to this the increased susceptibility of inpatients to infection, and if Legionnaires’ disease is contracted while individuals are in hospital, the healthcare-acquired CFR jumps to around 25%. Even more worryingly, the World Health Organization highlights that the death rate may be as high as 40–80% in untreated immunosuppressed patients.7
Need for strict protocols
Hospital construction projects are needed urgently, but there must be an acceptance that they come with an inherent risk of Legionella exposure. It is therefore essential to follow strict protocols and regulations to prevent the spread of the bacteria. Hospitals must have a robust risk assessment and water management plan in place, work with experienced contractors, and implement control measures to protect patients and staff. By taking a proactive approach to Legionella risk management, hospitals can ensure that construction projects are completed safely, and with minimal disruption to patient care.
Once the construction and refurbishment phases are over, and the hospital environment is returned to the high standards expected of a healthcare setting, staff may think they can relax in their approach to managing Legionella risk. Unfortunately, Legionella is a stubborn bacterium that will find a way to enter and command a water system if the conditions allow it, even in new modern buildings. There are several Legionella ‘watch-out’ areas in a hospital:
Cooling towers – as mentioned previously, cooling towers are a significant risk; the warm, moist conditions are an ideal breeding ground, and the erupting mist cloud can travel up to 10 km from the source.8
Water facilities – water systems, including hot and cold-water storage tanks, showers, taps, and sinks, can also provide an environment for Legionella growth. Stagnant water, biofilm formation, low flow rates, and inadequate temperature control, can all lead to the proliferation of the bacteria.
Respiratory care equipment – Legionella can grow in the water and be dispersed into the air via devices such as nebulisers and humidifiers. Potentially contaminated aerosols can then be inhaled
Decorative water features – water features such as fountains and pools can also provide a suitable environment for Legionella growth, particularly if the water is stagnant or not treated with adequate disinfectants. Ideally, these features should be avoided in hospitals and other healthcare settings.
Therapeutic pools, birthing pools, and hot tubs – pools and hot tubs are usually kept at the ideal temperature for Legionella growth (around 36-38°C), with the optimum temperature for growth being around 37 °C.8 Another consideration, therefore, is that this optimum temperature is also the human core body temperature, making our lungs the ideal environment as a host for Legionella.
Thermostatic mixing valves – TMVs can also provide an environment for the proliferation of Legionella bacteria if they are not correctly installed, maintained, or cleaned. The anti-scald design involves mixing hot and cold water, which can create the ideal water temperature for Legionella multiplication. Also, the inner design of these units is complex, and can harbour pockets of stagnant water, encouraging biofilm growth, which is difficult to remove.
A ‘never-ending battle’
It is true to say that Legionella is a never-ending battle. It is persistent and difficult to eradicate, and ultimately it can be deadly, so the management of Legionella in hospitals is critical. Hospital management shouldn’t see Legionella control as an ‘add-on’ to the day job, but as an imperative element of patient safety and care standards. Preventive measures may include maintaining appropriate temperature and pressure levels, regular cleaning and disinfection of water systems, and regular flushing to avoid stagnation, together with ongoing testing to detect Legionella presence.
It is a well-documented fact that one of the major risk factors for Legionella proliferation within a water system is temperature.9,10 The ideal temperature range which encourages the growth of Legionella bacteria is 20 °C to 45 °C (77-113 °F). Legionella isn’t a fan of temperature extremes, so creating a hostile environment by keeping cold water cold (below 20 °C), and hot water hot (above 60 °C in storage tanks, and above 50°C in the circulating system), is a simple yet effective step in helping reduce risk, and should be a minimal-level method of Legionella control in any water management process.
Disinfection
Disinfection has also proven itself to greatly reduce waterborne infections, and is one of the greatest advances in the prevention of disease in the last century, and maintaining levels within a water system will help keep Legionella in check. However, disinfectant presence in water systems can also conversely encourage the growth of OPPPs (Opportunistic Premise Plumbing Pathogens) like Legionella pneumophila. As disinfectant reduces the number of pathogens in the water, it also reduces the number of competitors for the available carbon and nutrients. Ironically, this can give OPPPs an increased opportunity to proliferate.11 Regular cleaning might involve the identification and removal of the biofilm which can be found in most water systems – natural and man-made, throughout the entire world. Biofilm is very common, and if you look inside taps, showerheads, pipework, or water tanks, you are likely to find biofilm residing within. It is widely considered that a majority of Legionella is locked in biofilm, and issues occur when sections of biofilm break off, leading to the release of the bacteria into the water, where they can clog up filters or deadlegs, and embark on their relentless journey to infect the whole water system. Biofilms also provide Legionella with protection from high temperatures in the water or chemical treatments, allowing them to proliferate into larger and more dangerous quantities uninterrupted.
A dormant state
It is really important to note, however, that when Legionella is exposed to stressful conditions such as starvation, chemical treatment (e.g. chlorination), heat shock treatments, low temperatures, and UV treatment, it can enter a dormant state called VBNC (Viable but Non-Culturable) Legionella. This dormant state suggests an adaptive strategy for the long-term survival of the bacteria under unfavourable environmental conditions, and as the name suggests, it cannot grow on conventional culture plates in a laboratory. It will therefore remain undetected if water testing programmes only rely on lab culture, as many healthcare settings do. When conditions become favourable again, VBNC Legionella may reactivate. VBNC Legionella is very dangerous, and has been shown to retain pathogenic properties despite restricted metabolic rates.12 It has been observed that VBNC bacteria have recovered their culturability after passage through human lung cells, which they can directly infect, suggesting that after VBNC bacteria are inhaled by a human, they have the potential to cause infection in the same way as culturable bacteria.13 It is clear that hospitals take grave risks when they only use lab culture methods to check their water systems for Legionella.
Hiding within the system
So, if a hospital finds Legionella, and takes steps to remove it, only to find that the bacteria is back again, it could be that VBNC Legionella is hiding within the system. Undertaking a test that can detect VBNC forms of the bacteria (e.g. antibody-based lateral flow tests or PCR) after all remedial work is critical to ensure efficacy.
The only way to know if culturable and VBNC Legionella is present in the water is to test it regularly. There are options available on the market to support a regular testing regime. Lab culture is considered the traditional method, and is required by many Legionella codes of practice, including the Department of Health and Social Care’s HTM 04-01: Safe water in healthcare premises document.14 This process can be lengthy, must be carried out by an accredited laboratory, takes around 10 days to receive results, and involves the transportation of samples, which can kill Legionella. Lab culture will test for all culturable Legionella species, including non-pneumophila, but will not detect VBNC Legionella.
The rapid testing option
Another option, which does not replace lab culture, but may help give a more immediate view of the Legionella health of a water system, and also checks the efficacy of remedial works, is rapid testing. PCR is classed as a rapid test, and will detect all species plus VBNC Legionella, but takes between 2-4 hours for the results, is a relatively complex process, and requires a high level of skill to conduct. Finally, there are rapid antigen tests like Hydrosense, which focuses on Legionella pneumophila, can be carried out by anyone with minimal training, and gives accurate results in 25 minutes.
Relying solely on lab culture is likely to not be effective enough, since by the time results are returned, the levels of Legionella in the system, if positive, will be dramatically increased. Adding another layer of detection will undoubtedly help to positively monitor and control Legionella risk. The health risk to patients and staff must be more important than simply ‘ticking the box’ when it comes to Legionella testing
Complete eradication of Legionella is very unlikely – due to the scale and complexity of the water systems in healthcare buildings, both old and new, and the survival instinct of the bacterium itself. However, by maintaining a robust water management programme, following the preventative measures outlined by the HSE, and regularly testing for and treating potential Legionella growth, healthcare facilities of all types can reduce the risk of their staff and visitors becoming ill from Legionnaires’ disease.
Greg Rankin
Greg Rankin, CEO at Hydrosense, is a ‘technology product veteran’, marketeer, and business developer. His 30+ year career has been ‘underpinned by innovation’. He has been responsible for product inception, product development, marketing, and sales, within the IT and SaaS industries, and has secured significant global deals, launched turnaround products, and – Hydrosense says – ‘delivered world-leading solutions’.
Today, he is an ambassador for protecting lives against Legionnaires’ disease, and for finding Legionella quickly to help keep businesses operational and protected from potential reputational damage. He has spent the past six years leading the team at Hydrosense, and driving the technological and digital advances to realise those beliefs – ‘delivering solutions that work quickly and accurately to detect the Legionella pneumophila species’, ultimately delivering what Hydrosense claims is ‘the world’s fastest Legionella testing kit’
References
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