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Fighting the superbugs: resistance to antibiotics means that a traditional material is making a comeback in the war against hospital-acquired infections.

The rise of superbugs apparently resistant to the charms of antibiotics has put renewed emphasis on contamination control in hospitals and other places where we go expecting to emerge in better shape than when we went in. And it's given impetus to a quiet campaign that's been waged over many years by proponents of an older but apparently effective technology.

For years past, the Copper Development Association, a metals industry pressure group, has been talking up the antibacterial properties of copper. As an industry group, the association, and its international copper siblings, can't really be accused of disinterest. But what's become apparent, as MRSA, C. difficile and norovirus stalk the corridors, is that their message is true.

Copper and copper compounds and alloys kill bacteria. The properties have been known about, in an unofficial folklorish way, for centuries, and silver and silver compounds have long been thought to do the same. But only in recent years has there been scientific investigation of the phenomenon--and even now, the mechanism is still being researched.

What appears to happen is a chemical reaction between the copper and the DNA and RNA of genes that stops bacterial propagation. The gene mechanism is important. Bill Keevil, professor of environmental healthcare at Southampton University, has been investigating horizontal gene transfer (HGT) in bacteria, which is largely responsible for the development of antibiotic resistance.

Much of the work in this area has looked at HGT inside organisms, but Professor Keevil looked into the survival of pathogens on surfaces. He found that the common E. coli and Klebsiella pneumoniae bugs were able to survive happily on stainless steel surfaces for several weeks.

"However, rapid death of both antibiotic-resistant strains and destruction of plasmid and genomic DNA was observed on copper and copper alloys surfaces, which could be useful in the prevention of infection spread and gene transfer," he said.

The research suggests that antibiotic resistant genes are being transferred from surface to surface as people touch them. Professor Keevil says there are obvious implications in this for hospitals, where superbugs have caused huge problems in recent years. "What we have shown is the potential for strategically-placed antimicrobial copper touch surfaces to not only break the chain of contamination, but also actively reduce the risk of antibiotic resistance developing at the same time he said.

But he believes this could go further: "Copper touch surfaces have promise for preventing antibiotic resistance transfer in public buildings and mass transportation systems, which lead to local and, in the case of jet travel, rapid worldwide dissemination of multidrug-resistant superbugs as soon as they appear."

The difficulty that copper faces in establishing itself as a material for surfaces in these potentially massive markets is the perception of cost. The International Copper Association has been trying to meet this perception head on by engaging the healthcare economists at the York Health Economics Consortium to come up with a cost-benefit analysis model, pitching the cost of installing limited numbers of copper surfaces against the benefit in terms of reduced infections.

The model lets individual hospitals or health trusts insert their own figures for costs, both of installing the surfaces and of the treatment for infected people. One that has already done so is the University Hospitals Birmingham NHS Trust, where consultant microbiologist Professor Tom Elliott worked out that the cost of installing surfaces in a 20-bed hospital ward was equivalent to the cost of 1.5 infections over the lifetime of the surfaces, which is reckoned to be many years.

The focus for contamination control work using copper and copper alloys has so far been on hospitals because of the specific problem of superbug infections in places where people go with the aim of getting better, not worse. Extension of the work into wider cleanroom operations and into contamination control in industry and research work is not currently under consideration, and the practicalities and the economics would be very different.

But the potential is there.
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Title Annotation:Contamination Control
Publication:Environmental Engineering
Date:Feb 1, 2013
Words:660
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