Novel antibacterial silver-silica surface coatings prepared by chemical vapour deposition for infection control
Environmental contamination plays an important role in the transmission of infections, especially healthcare-associated infections. Disinfection transiently reduces contamination, but surfaces can rapidly become re-contaminated. Antimicrobial surfaces may partially overcome that limitation. The antimicrobial activity of novel surface coatings containing silver and silica prepared using a flame-assisted chemical vapour deposition method on both glass and ceramic tiles was investigated.
Methods and Results
Antimicrobial activity against a variety of bacteria including recent clinical isolates was investigated based on the BS ISO 22196:2007 Plastics – Measurement of antibacterial activity on plastics surfaces, British Standards Institute, London, method. Activity on natural contamination in an in use test in a toilet facility was also determined. Activity on standard test strains gave a log10 reduction of five after 1–4 h. The hospital isolates were more resistant, but MRSA was reduced by a log10 reduction factor of >5 after 24 h. Activity was maintained after simulated ageing and washing cycles. Contamination in situ was reduced by >99·9% after 4 months. Activity was inhibited by protein, but, although this could be overcome by increasing the amount of silver in the films, this reduced the hardness of the coating.
The coatings had a good activity against standard test strains. Clinical isolates were killed more slowly but were still sensitive. The optimum composition for use therefore needs to be a balance between activity and durability.
Significance and Impact of the Study
The coatings may have applications in health care by maintaining a background antimicrobial activity between standard cleaning and disinfection regimes. They may also have applications in other areas where reduction in microbial contamination is important, for example, in the food industry.