Costs: Anti-bacterial surfaces

There is a range of measures in place to limit the prevalence of acquired infections in hospitals and healthcare facilities. These are related to good hygiene, cleaning and surveillance. Infections are typically passed on through contact with infected people or items. There is also an argument for using building components with anti-bacterial coatings to limit cross-contamination. However, authoritative guidance on using anti-bacterial building components in healthcare buildings is limited.

Anti-bacterial building components may help but even the most effective take an hour or two to kill bacteria, during which time infections could be passed on. It is also important to note that they may not deal with all bacteria. Nevertheless, anti-bacterial building components are increasingly being specified.

The skill for designers is to achieve a balance between the additional cost of specifying anti-bacterial components and the likely effect in reducing acquired infections. Ideally this should be based on evidence for the efficacy of anti-bacterial surfaces in the context of infection risk and cost. Data from 1999 suggests that at least 300,000 patients a year develop one or more infections - the extra costs associated with infection because of patients staying longer in hospital and receiving additional treatment is about £3000 per case.

Anti-bacterial components

Anti-bacterials are based on metals such as silver, copper, titanium or antiseptic hydrocarbon compounds. Some materials or compounds are anti-microbial, which means they kill or slow the growth of fungi, viruses or parasites, as well as bacteria. Practically all building components can be treated to have anti-bacterial properties by applying an anti-bacterial coating, manufacturing the component from materials that are intrinsically anti-bacterial or including an anti-bacterial material or compound in the base material of the component.

Specification options

A common-sense approach to specifying anti-bacterial surfaces is to target areas where risk of contamination is high, such as intensive care, or components where there is a high risk of cross-contamination, such as door handles, push plates or toilet seats. The anti-bacterial content may influence the durability of components where it deteriorates or become less effective with time. The cost of components with anti-bacterial surfaces varies, typically being 0-20% higher than an equivalent component without anti-bacterial surfaces. Calculating the whole-life costs relies on making assumptions about the probability of infection occurring as well as taking into account differences in capital, replacement and maintenance costs.

Coatings

Anti-bacterial formulations may be added to paint for walls with expected repainting frequencies of between two and 10 years. Performance of coatings can be assessed according to the relevant parts of the paint and varnish standard BS 3900. For example, good adhesion is tested to BS 3900-E6, resistance to cleaning and scrubbing to ISO 11998, impact to BS 3900-E3, humidity to BS 3900-F9, scratching to ISO 1518 and abrasion to BS 3900-E14.

Doors

Doors may be made from steel with an anti-bacterial powder-coated finish or glass-reinforced fibre impregnated with anti-bacterial formulations. Typical service lives are 20-40 years. The performance of the hinge should be to the appropriate duty grade to BS EN 1935. Protection from impacts should be provided.

Door furniture

Anti-bacterial options are available for practically all items of door furniture using:

• Copper or copper alloy door furniture - expected service life 10-40 years.
• Proprietary metal based anti-bacterial thin coatings on steel ironmongery - expected service life 10-15 years.

The range of building components incorporating anti-bacterials includes ceramic glazes, floor coverings and matting, floor coatings, sealants, worktops, curtains, luminaires, suspended ceiling systems, ventilation and air-conditioning filters. Specification guidance for many components can be found in the newly revised NHS Health Technical Memorandum. However, these do not generally mention anti-bacterial options.