Why copper busts bacteria

(Nanowerk News) Researchers in the United Kingdom have discovered that copper has the ability to prevent the horizontal transmission of genes, which has fuelled the spread of global antibiotic-resistant infections. The finding was recently published in the journal mBio ("Horizontal Transfer of Antibiotic Resistance Genes on Abiotic Touch Surfaces: Implications for Public Health").
The University of Southampton scientists say horizontal gene transfer (HGT) in bacteria plays a major role in the development of antibiotic resistance, which triggers headaches for researchers who are trying to find ways to treat healthcare-associated infections (HCAIs).
Despite the fact that HGT emerges in various environments, including buses, trolleys, door handles and frequently touched surfaces, copper not only puts a stop to this process but it also kills bacteria on contact.
'Whilst studies have focused on HGT in vivo, this work investigates whether the ability of pathogens to persist in the environment, particularly on touch surfaces, may also play an important role,' said senior author Bill Keevil, head of Environmental Healthcare at the University of Southampton. 'Here we show prolonged survival of multidrug resistant Escherichia coli and Klebsiella pneumoniae on stainless steel surfaces for several weeks. However, rapid death of both antibiotic-resistant strains and destruction of plasmid and genomic DNA [deoxyribonucleic acid] was observed on copper and copper alloy surfaces, which could be useful in the prevention of infection spread and gene transfer.'
By demonstrating the connection between touch surfaces and horizontal transmission of genes, the team added weight to the theory that the environment contributes significantly to the prevention of infection.
'We know many human pathogens survive for long periods in the hospital environment and can lead to infection, expensive treatment, blocked beds and death,' Professor Keevil said. 'What we have shown in this work 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. Provided adequate cleaning continues in critical environments, copper can be employed as an important additional tool in the fight against pathogens.'
The Southampton professor pointed out that copper can also impact infection control, noting that copper touch surfaces can help prevent antibiotic resistance transfer in public buildings and mass transportation systems, which trigger dissemination of multidrug-resistant superbugs on both the local and international fronts.
'People with inadequate hand hygiene could exchange their bugs and different antibiotic resistance genes just by touching a stair rail or door handle, ready to be picked up by someone else and passed on,' Professor Keevil said. 'Copper substantially reduces and restricts the spread of these infections, making an important contribution to improved hygiene and, consequently, health.'
Copper touch surfaces have already appeared in the United Kingdom, but more are expected to come.
Source: Cordis