Researchers from the University of Southamptom in the UK have shown that copper may help slow the global spread of antibiotic-resistant infections by preventing horizontal gene transfer (HGT) in bacteria that can survive outside the body, such as on frequently touched surfaces like door handles and tables.

They write about their new study in a paper published online in the journal mBio on 27 November.

Horizontal gene transfer (HGT) is where genetic material transfers directly between bacteria outside of the usual cell division.

HGT is thought to be the main reason bacteria are becoming antibiotic resistant, contributing to a worldwide epidemic of hospital and community acquired infections caused by multidrug-resistant microorganisms or “superbugs”.

In a paper published in Nature in 2011, researchers described how bacteria linked to humans and their livestock exchange genetic information rapidly, including coding for antibiotic resistance through HGT.

Lead author of this latest mBio paper, Professor Bill Keevil, Chair in Environmental Healthcare at the University, says in a statement released on Tuesday:

“Whilst studies have focussed on HGT in vivo (an experiment that is done in the body of a living organism), this work investigates whether the ability of pathogens to persist in the environment, particularly on touch surfaces, may also play an important role.”

In their study, Keevil and colleagues show while HGT can take place among bacteria in the environment, for instance on frequently touched surfaces such as tables, trolleys and door handles, which are made of stainless steel, materials made of copper seem to stop it, and also kill the bacteria on contact.

They found the multidrug resistant superbugs Escherichia coli and Klebsiella pneumoniae could survive on stainless steel surfaces for weeks.

But on copper and copper alloy surfaces, both the Escherichia coli and the Klebsiella pneumoniae resistant strains died quickly and their DNA was destroyed:

“Rapid death, inhibition of respiration, and destruction of genomic and plasmid DNA of both pathogens occurred on copper alloys …” write the authors.

This suggests surfaces made from these materials “could be useful in the prevention of infection spread and gene transfer,” says Keevil.

Keevil notes that we know that many human pathogens can survive for long periods in hospitals, where they cause infections that are difficult to treat, leading to increased costs, blocked beds and even deaths.

Keevil says their research suggests strategically placing anti-microbial copper on frequently touched surfaces would not only “break the chain of contamination” but could also “actively reduce the risk of further increasing antibiotic resistance”.

“Provided adequate cleaning continues in critical environments, copper can be employed as an important additional tool in the fight against pathogens,” he urges.

The researchers believe copper could also be used outside hospital settings to control infection, such as in public buildings and transport systems, where jet travel helps superbugs spread quickly worldwide almost as soon as they appear.

Copper surfaces are already being installed in the UK and other countries.

Written by Catharine Paddock PhD