Buildings that kill bacteria

Silver in various forms has long been known to act as a natural antibiotic. Photo / Supplied

This post originally appeared on sciblogs.co.nz.

In an effort to control the spread of bacteria which are harmful to humans, the science world is always coming up with interesting innovations. This now includes additives to building materials that will kill bacteria, including the dreaded MRSA strain.

Antimicrobial, antibacterial and antifungal powder-coating has been available commercially for a few years, and now scientists have developed an additive for paint that targets only staph bacteria.

The innovation comes in how these materials can provide lasting protection, despite some surfaces like door handles and handrails getting a lot of human interaction.

In the case of the powder-coating, the manufacturers have added silver ions to the powder coating material and found a way to keep the ions distributed through the coating once it is applied and heat fused onto the (typically metal) substrate. Powder-coating is often used as the aesthetic and protective coating on metals, such as handrails, door handles, window and door frames, furniture frames, equipment frames, etc.

Silver in various forms and silver ions have long been known to act as a natural antibiotic, dating back centuries, although it has fallen in and out of favour over time as medical knowledge has changed. The silver ions interrupt the replication ability of proteins within the bacteria, making them inactive. Having done testing for effectiveness and gaining US FDA and EPA approvals for food contact, the company that makes this powder-coating is now promoting it for use wherever you want to stop the possible spread of bacteria.

The paint additive is reported to kill MRSA without the use of antibiotics. Using carbon nanotubes bound with lysostaphin, it is the lysostaphin that does the damage.

The report identifies lysostaphin as a naturally occurring enzyme used by non-pathogenic strains of Staph bacteria to defend against Staphylococcus aureus, including MRSA. Lysostaphin works by first attaching itself to the bacterial cell wall and then slicing open the cell wall. That means it's a highly-targeted substance - in fact, it only destroys staph bacteria.

This looks to work well in the lab, but it has yet to be turned into a commercially available product.

Although we have had fungicidal paint for some time, and it is sometimes used in high humidity areas, the concept of using building materials, or in this case entire wall surfaces, to act as an antibacterial agent is certainly an interesting development. On the face of it the advantages could be many, especially if it means that the building environment is helping to reduce the number of places harmful bacteria can sit and be transferred from person to person.

However, a concern that has been expressed is the evolutionary process, where we have already seen bacteria become resistant to some commonly used antibiotics. If these products are widely used, will bacteria evolve to become resistant to the active parts of these building products? Only time will tell.

Ken Collins is the founder of Lab-works Architecture Ltd, which specialises in the design of scientific laboratories. View his work and that of 30 other scientists and science writers at Sciblogs, New Zealand's largest science blogging network.