Metallic copper surfaces kill microbes on contact, decimating their populations, according to a paper in the February 2011 issue of the journal Applied and Environmental Microbiology.
They do so literally in minutes, by causing massive membrane damage after about a minute’s exposure, says the study’s corresponding author, Gregor Grass of the University of Nebraska, Lincoln. This is the first study to demonstrate this mechanism of bacteriocide.
“When microbes were exposed to copper surfaces, we observed contact killing to take place at the rate of tens to hundreds of millions of bacterial cells within minutes,” says Grass. “This means that usually no live microorganisms can be recovered from copper surfaces after exposure.”
Thus, such surfaces could provide a critical passive defense against pathogens in hospitals, where hospital-acquired infections are becoming increasingly common and costly, killing 50,000-100,000 Americans annually, and costing more than $8 billion, according to one estimate. Still, Grass cautions that “metallic copper surfaces will never be able to replace other hygiene-improving methods already in effect,” although they “will certainly decrease the costs associated with hospital-acquired infections and curb human disease as well as save lives.” However, he expects this strategy to be inexpensive, because “the effect does not wear off.”
Critically, the researchers provide strong evidence that genotoxicity through mutations and DNA lesions is not a cause of dry copper’s antimicrobial properties. This is important, because mutations can cause cancer in animals and humans, and the lack of such mutations in bacteria from copper means that copper does not endanger humans.