Water/Wastewater

  • Validate Recommissioning and Remedial work in 25 minutes

Validate Recommissioning and Remedial work in 25 minutes

Sep 21 2020 Read 1117 Times

There are growing concerns amongst public health and water management professionals about the threat of Legionnaires’ disease as buildings such as factories, schools, hairdressers, cinemas and shops reopen, especially where water systems have not been maintained during lockdown, or decommissioning has not been carried out with proper care.

In a recent article in The (London) Times, Professor Hugh Pennington, professor of bacteriology at the University of Aberdeen, warned that potentially deadly Legionella bacteria will have been growing in factories and other businesses during this period of closure. He cautioned that if this is the case, then these facilities can expect a Legionella outbreak, if not several when they start re-opening.

Legionella bacteria, which causes a potentially fatal pneumonia-like infection, with practically identical risk groups and symptoms to COVID-19, thrives in stagnant water and presents a serious public health risk, especially where systems have not been flushed, have had low to no use over lockdown, have experienced thermal gain or where there has been substantial growth in biofilm (which can act as a host for Legionella bacteria and can protect it from heat and chemical treatment).

In many buildings lockdown has caused low flow and system stagnation which can lead to thermal gain, low disinfection residuals at outlets and biofilm formation. These factors provide Legionella with ideal conditions for growth and resuscitation from a dormant state (VBNC).

Legionella thrives in temperatures ranging between 20°C and 45°C, temperatures which can be reached as a result of stagnant water sitting in the pipes warming up or cooling down. Stagnation and warm temperatures can also support the growth of biofilm (a slime-like layer that protects micro-organisms from disinfection and biocides by providing nutrients and a physical barrier from treatment). As a result, it helps pathogens like Legionella to proliferate and resist treatment.

Around 90% of bacteria is found in biofilm and 90% of Legionella in biofilm are in a VBNC state. VBNC Legionella is Legionella in a state of reduced activity, normally induced by stressful conditions. These dormant bacteria present a serious risk for buildings who have experienced stagnation in the pipes during lockdown.

Recent research suggests that biofilm impacts Legionella’s ability to infect amoeba or human lung cells. Worryingly, it seems that Legionella that has long been resident in biofilm can be much more deadly. Studies indicate that Legionella which originate from biofilm can avoid immune responses in human macrophages in the lungs thus allowing for more successful infectivity.

To make things worse, VBNC Legionella cannot be detected using the lab culture method, meaning that risk presented by VBNC bacteria can easily be missed with standard testing until there is an outbreak or someone falls ill.

This risk was recently identified at Maples Medical Care Facility in the United States after a patient was diagnosed with Legionellosis. The facilities administrator stated that the Legionella that caused the infection may have been sitting dormant in the system for two years prior to detection and that stagnation had allowed the bacteria to resuscitate and grow.

Hydrosense recently polled a diverse group of water management professionals from all around the world to find out just how critical speed of recommissioning was for them and their customers after lockdown. 93.3% of water management professionals and duty holders we asked said that speed of recommissioning was absolutely critical, suggesting that clients are in desperate need of ultra-fast tools which help them to accelerate maintenance and minimise downtime.

It is also crucial for long-term water safety that dormant bacteria can be detected by the testing methods being used on sites. As we now know, traditional Legionella testing methods (the laboratory culture method especially) is unable to detect VBNC bacteria. To avoid cases like the one seen at Maples, targeted solutions which are able to detect VBNC Legionella are highly recommended.

“While it usually takes a lab up to 14 days to process Legionella samples, Hydrosense can help speed up the recommissioning process by helping water engineers to spot high risk problems in only 25 minutes. This allows for corrective action to be taken almost immediately, and without having to wait two weeks for a lab culture result only to find out more flushing or biocide is required.” – Greg Rankin, Hydrosense CEO

The Hydrosense Swab range can also detect VBNC Legionella pneumophila serogroup 1 in biofilm, helping to detect VBNC risk that the lab culture method will always miss. Hydrosense provides a rapid indication of the success of recommissioning, allowing businesses to get back to 'business as usual' quickly, and safely. And helps duty holders identify problems with VBNC early and minimise the risk of an outbreak.

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