WATER SYSTEM HYGIENE AND SAFETY
Water systems, including hot and cold water storage tanks, showers, taps, and sinks, can provide an environment for Legionella.
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: n 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
n 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.
n 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.
n 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.
n 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.
n Thermostatic mixing valves – TMVs can also provide an environment for the proliferation of Legionella bacteria if they are not correctly installed, maintained, or
May 2023 Health Estate Journal 47
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