Legionellosis is the collective name given to the pneumonia-like illness caused by legionella bacteria. The most serious is Legionnaire’s disease, which is potentially fatal. Legionella bacteria live in water supplies so dental practices have a duty of care to protect their patients and staff from potential harm.
Everyone is susceptible to infection. However, those over the age of 45, smokers and heavy drinkers, sufferers of chronic respiratory or kidney disease and those with an impaired immune system are most at risk.
Water companies are required to keep levels of water-born bacteria in drinking water within very strict limits – just 100 Colony Forming Units (CFUs). Research reveals that bacterial counts in dentists’ waterlines can far exceed these. One study showed colony sizes of 19,500 CFUs, so legionella control needs to be taken seriously.
Why are dentists’ water systems at risk?
They provide suitable environmental conditions for biofilm and bacterial growth, namely:
- a source of nutrients for the bacteria
- plasticisers in the plastic tubing of the waterlines
- ambient water temperatures
- potentially stagnant water conditions overnight and at weekends
Are there legal requirements in relation to legionella in dental practices?
Yes, they have been set by the Care Quality Commission (CQC). The CQC standards include:
- identifying and assessing the sources of risk
- preparing a legionella risk assessment
- preparing a scheme to prevent or control such risk – to be upheld by the registered practice manager
- appointing a responsible person to undertake legionella testing and care procedures.
- implementing, managing and monitoring legionella control precautions
- keeping records of these precautions
Do dental lines require routine microbiological monitoring?
Unless there are taste or odour problems, microbiological monitoring for total viable counts is not considered necessary.
How often should legionella testing be carried out?
This depends on the system in place and the outcome of the risk assessment.
What procedures should I adopt to to reduce microbial accumulation?
As no one product is 100% effective in controlling legionella, a variety of products should be used periodically, in accordance with the manufacturers’ instructions.
The water supply should be isolated from the mains, using an independent bottled water system on the unit. This bottle should be filled with freshly distilled/reverse osmosis water at the start of each day. Tap water should not be used as it will result in the introduction of opportunistic respiratory bacteria to the waterline, which would rapidly lead to biofilm formation.
Waterlines should be regularly flushed – for 2-3 minutes at the start of each session and for 20-30 seconds between patients. An inspection checklist is useful to ensure compliance and provide auditable evidence.
At the end of the day, the bottle should be disconnected, emptied, rinsed and stored inverted – clean and dry – overnight.
Where can I find more guidance on legionella control?
There is specific guidance on the care of dental unit water lines in the government’s ‘Health Technical Memorandum 01-05: Decontamination in primary care dental practices’ which sets out the legal requirements and recommends the engagement of a specialist. You can download it here
The HSE has published a booklet called ‘Legionnaires’ disease. The control of legionella bacteria in water systems’ It is aimed at duty holders, to help them comply with their legal duties in relation to legionella and sets out the role of the appointed ‘responsible person.’ It can be purchased here
The Department of Health has produced Memorandum 04-01: Safe water in healthcare premises which is intended to help promote holistic management of water systems via Water Satety Groups (WSGs), Water Safety Plans (WSPs) and other initiatives. It can be downloaded here
Guardian is able to offer expert advice on Legionella testing, risk assessment and control, including compliance with ACOP L8 – the Approved Code of Practice L8 2013 – The Control of Legionella Bacteria in Water Systems.
Failure to comply puts people’s health at risk and if an issue did occur, this failure could be used in criminal proceedings as evidence of a company’s negligence. For more details click here