Persistent legionella bacteria in the water system of a healthcare premises.

Case Study for promotion of use of hydrogen peroxide stabilised with silver ions for control of legionella bacteria in hot and cold water services.

Background – A healthcare premises in the Midlands with a comprehensive written legionella control scheme in place was experiencing repeated legionella positive samples (despite carrying out various remedial works to improve their water system to the current standards and recommendations). Continuous chemical dosing had been discussed as an additional control strategy but the site management team wanted to attempt further remedial works and system modifications first.

Managed Water Services supported and assisted the client with remedial works and modifications and this was done in tandem with repeated disinfections of the system in response to legionella positive samples being received (See Fig.1).  Disinfection of the system was operationally difficult due to the patient profile present on site.  Persistent disruption to operations resulted in patients and staff becoming frustrated.  The CQC had also picked up on the issues during a recent inspection which had caused more work for the centre management.

Fig. 1 – samples with legionella detected were commonplace

Solution –  A proposal was accepted to install and commission a continuous dosing plant on the supply to the hot and cold water services.  By installing a water meter and intelligent pump the chemical can be safely dosed to the required limits (See Fig.2).

Fig.2 – a water meter and intelligent dosing pump was installed onto the supply to the hot and cold water services

The science – The chemical being continually dosed was an ecological, universal and antiviral disinfectant based on hydrogen peroxide and silver.  The chemical used can eliminate all pathogenic amoeba, bacteria, biofilms, fungi, moulds and viruses through simple chemistry that allows silver ions within the solution to react with proteins produced by bacterium to protect the cell wall from being destroyed.  This then allows the hydrogen peroxide in the formula to destroy the cell wall and eliminate the bacterium.

Benefits –

  • The chemical used has no taste, is colourless and has no smell. The product has over 200 tests to endorse safety and efficacy.
  • The new installation has eliminated the need for emergency disinfections and ensured compliance with HSG274.
  • Importantly, the centre’s management team are not spending their time managing reactive maintenance tasks and having to explain to patients, staff and the CQC what is being done.
  • Maintaining system control in the future will be less intrusive to patients and staff as there will be fewer visits needed from Managed Water Services engineers.
  • Within 12 months, the new system will prove to be less costly than repeated system disinfections.
  • All involved will have peace of mind that control has been returned to the systems.

Outcome – Once the plant was commissioned, samples were taken fortnightly to determine if control was being maintained.  At the time of writing, all samples returned since installation have returned with no traces of legionella bacteria detected (see Fig.3).

Fig.3 – so far the samples have been returned with legionella bacteria not detected