Armed against nosocomial infections

June 2013

Controlling bacterial growth by monitoring water quality is essential to reduce nosocomial infections. Following on from Legionella, it is Pseudomonas aeruginosa that has become the focus of attention. Specially designed mixers and taps are essential to limit the spread of these pathogens in the healthcare sector. 

The biofilm formed naturally in the fittings and pipes houses 99.5% of bacteria in healthcare facilities. Impossible to eradicate, it must be controlled in order to limit the proliferation of pathogenic bacteria. The goal is to prevent germs from multiplying and forming aggregates that can easily get into the water flow. When a tap is turned on, these bacteria may be released into the air in micro-droplets (aerosols). For vulnerable people, including the immuno-compromised, contact with certain microorganisms is synonymous with the risk of infection. Bacteria in the water supply are responsible for approximately 30% of nosocomial infections. It is therefore necessary for health facilities to control bacterial growth in their sanitary installations.

Wanted: Legionella and Pseudomonas

For example, in France, since 1st January, 2012, all Institutions Receiving the Public (IRP) are subject to the monitoring of the bacteriological quality of the water, in so far as the general public have access to the points-of-use and aerosols can be formed from hot water systems where there is a risk of Legionella.

The Health and Safety Executive (HSE) L8 Approved Code of Practice and Guidance** requires the bacteriological quality of water to be monitored in sanitary installations in buildings where the Health and Safety at Work Act 1974 applies. This identifies the procedure for measuring the temperature of the water and the search for Legionella in all water systems.

Minimum hot water temperatures have been identified to reduce the risk of Legionella developing; and a thermostatic mixing valve is recommended to provide safe hot water at the point-of-use to reduce the risk of scalding.

Until recently, no special requirements were in place to monitor for Pseudomonas aeruginosa. This so-called point-of-use bacterium develops in the presence of oxygen and water, mainly in mixer and tap spouts. Once established in the spout interior, the pyocyanic bacillus (another name for the germ) gradually colonises the body of the mixer/tap, then the tails, then the pipe work. At this point, it becomes impossible to eliminate, hence it is the second most common cause of life-threatening hospital infections.

Recommendations for Pseudomonas

In March, 2012 the National Health Service (NHS), published a guide to good practice to detect Pseudomonas aeruginosa in healthcare facilities, and appropriate action in the event of contamination. It recommends that the sampling strategy should be to take the first sample of water (pre-flush) at least 2 hours after the last draw-off (preferably 5 hours) for taps used daily, and to test the taps that are used infrequently. In the absence of contamination, repeat tests should occur every 6 months. The NHS states that the alert level for action is from 1 CFU / L (Colony Forming Unit of Pseudomonas aeruginosa per litre of water). At levels between 1 and 10 CFU / L, the test should be repeated and curative measures put in place. Above 10 CFU / L, the cause of these results should be investigated and an engineering study maybe undertaken to identify remedial actions to be implemented.

Specifically Designed Product Ranges

NHS recommendations, in conjunction with the BIOSAFE solutions developed by Delabie in recent years, help to control bacterial growth in hospital water controls. Several specialist controls have been developed by the manufacturer: The BIOCLIP range has removable elements, allowing thorough internal cleaning and specialist spouts to be fitted. The mixer or tap can be fully removed from its base, or just the spout can be removed from the body. Removable spouts come in three options: brass, disposable, or filter. This latter spout incorporates a filter, sterilising grade 0.1 microns absolute rated, which delivers bacteria-free water. Water controls with low volumes of standing water have specifically designed interiors which reduce the volume of water in the body. The interior passages have no corners, and can accelerate the speed of the water, limiting the development of biofilm. Water controls with smooth body and/or spout interiors  have no niches where biofilm can adhere, unlike most mixers and taps whose bodies and spouts have rough interiors where bacteria can attach(a study showed that taps with smooth bodies have Pseudomonas aeruginosa contamination levels 14 times lower than for taps with rough bodies*).

Finally, electronic controls with an automatic duty flush prevent water stagnation, one of the leading causes of bacterial growth in water systems. A periodic flush occurs automatically for 45 seconds, 24 hours after the last use.

Each solution addresses a specific constraint. The combination of several solutions can increase the level of precautions against bacterial pathogens.


* Study conducted in June 2010 by the BioPI laboratory and the Department for Biological Studies at the Jules Verne University, Amiens
** The Health and Safety Executive L8 Approved Code of Practice and Guidance: Legionnaire’s disease: The control of legionella bacteria in water systems (2004)