Decon Pete – water quality and the potential risks of legionella

This month Decon Pete discusses legionella formation and things to consider when reopening dental surgeries.

Water quality, within dentistry, is an extremely important element that needs maintaining to reduce any potential pathogen risk. In particular legionella pneumophila.

Dental practices have, for some time now, not been operating at full capacity. With many utilising additional surgeries for the donning and doffing of PPE.

With these surgeries not in use, as initially intended, it could result in issues with the water lines that staff members might not notice.

The surgery taps, unless run routinely every day, would result in dead legs forming in the water system. These dead legs are a perfect breeding ground for pathogens such as legionella.

Legionella formation

As discussed, in a previous article, the longer that water remains static the greater the chances of biofilm formation.

Biofilms form when individual bacteria, in a water line/pipe, adhere to the tube surface. When many bacteria adhere, a mechanism called quorum sensing changes the way that the adhered bacteria behave. The adhered bacteria then secrete a protective polysaccharide slime, forming a continuous film.

Before reopening an unused surgery we need to ensure that we have run through a few things.

Ensure that a biocidal agent is run through the treatment centre as part of the re-commissioning procedure. Run the cold water supply for two minutes and ensure that the temperature doesn’t exceed 20°C.

Run the hot water supply for one minute and ensure that the temperature doesn’t drop below 50°C.

If you believe that you may have a legionella problem with your mains supply, then the use of a Point of Use filter is advantageous at protecting staff and patients from the disease. These filters will stop any bacteria, down to 0.2nm. And they prevent further transmission.

UK guidance documents has the following to say about POU filters:

‘19.63: Point-of-use filters must be changed in accordance with manufacturers’ recommendations, typically at least once a month. When changing filters, we recommend water-quality sampling takes place at outlets identified as sentinel points before refitting a replacement filter. Except where taking samples as above, once introducing point-of-use filtration, practices must not use taps or showers without a filter in place.’

To ensure that we have good quality water and no significant biofilm issue, I would also recommend the use of a microbiological dip slide carried out every three months.

This will help to provide us with the safe knowledge that we have any biofilm issues under control.

To read the full article post click here.

If you or your company requires a pre commission disinfection please feel free to contact Black Sheep.

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