Interest in (and research into) the real-world efficacy and kill mechanisms of metallic copper surfaces against microbes (bacteria, viruses, yeasts and fungi) is accumulating.
Here are some recent papers for you:
Michels HT, Keevil CW, Salgado CD, Schmidt MG. 2015. From Laboratory Research to a Clinical Trial: Copper Alloy Surfaces Kill Bacteria and Reduce Hospital-Acquired Infections HERD, October 2015 vol. 9 no. 1 64-79,
This paper, published in HERD, helps summarise and explain the mechanisms, efficacy and benefits of copper & copper-alloy touch surfaces (collectively called “Antimicrobial Copper”).
It is open-access, so you can download the full pdf without cost.
Warnes SL, Little ZR, Keevil CW. 2015. Human coronavirus 229E remains infectious on common touch surface materials. mBio 6(6):e01697-15. doi:10.1128/mBio.01697-15.
Animal coronaviruses that ‘host jump’ to humans, such as SARS and MERS, result in severe infections with high mortality. The Southampton researchers found that a closely-related human coronavirus – 229E – can remain infectious on common surface materials for several days, but is rapidly destroyed on copper.
Hans M, Mathews S, Mücklich F, Solioz M. 2015. Physicochemical properties of copper important for its antibacterial activity and development of a unified model. Biointerphases 11, 018902 (2016); doi: 10.1116/1.4935853
Abstract: Contact killing is a novel term describing the killing of bacteria when they come in contact with metallic copper or copper-containing alloys. In recent years, the mechanism of contact killing has received much attention and many mechanistic details are available.
The authors here review some of these mechanistic aspects with a focus on the critical physicochemical properties of copper which make it antibacterial. Known mechanisms of contact killing are set in context to ionic, corrosive, and physical properties of copper.
The analysis reveals that the oxidation behavior of copper, paired with the solubility properties of copper oxides, are the key factors which make metallic copper antibacterial. The concept advanced here explains the unique position of copper as an antibacterial metal. Based on our model, novel design criteria for metallic antibacterial materials may be derived.
Meyer, T.J. 2015. Antimicrobial Properties of Copper in Gram-Negative and Gram-Positive Bacteria. International Journal of Biological, Biomolecular, Agricultural, Food and Biotechnological Engineering. Vol:9, No:3.
Abstract: For centuries humans have used the antimicrobial properties of copper to their advantage. Yet, after all these years the underlying mechanisms of copper mediated cell death in various microbes remain unclear. We had explored the hypothesis that copper mediated increased levels of lipid peroxidation in the membrane fatty acids is responsible for increased killing in Escherichia coli.
In this study we show that in both gram positive (Staphylococcus aureus) and gram negative (Pseudomonas aeruginosa) bacteria there is a strong correlation between copper mediated cell death and increased levels of lipid peroxidation.
Interestingly, the non-spore forming gram positive bacteria as well as gram negative bacteria show similar patterns of cell death, increased levels of lipid peroxidation, as well as genomic DNA degradation, however there is some difference in loss in membrane integrity upon exposure to copper alloy surface.
These papers are also recommended:
Taylor M, Chaplin S. 2013. The Economic Assessment of an Environmental Intervention: Discrete Deployment of Copper for Infection Control in ICUs. Antimicrobial Resistance and Infection Control 2013, 2(Suppl1):P368
This paper is the York Health Economics Consortium research into the cost-effectiveness and payback of copper touch surfaces. Read more, with a worked example for a UK 20 bed ICU, in this pdf document YHEC Business Case
More information on YHEC website https://www.york.ac.uk/news-and-events/news/2013/research/antimicrobial-copper/
Warnes SL, Keevil CW. 2011. Mechanism of copper surface toxicity in Vancomycin-resistant enterococci following wet or dry surface contact. Applied and Environmental Microbiology, Sept. 2011. pp. 6049–6059.
Abstract: Contaminated touch surfaces have been implicated in the spread of hospital-acquired infections, and the use of biocidal surfaces could help to reduce this cross-contamination.
In a previous study we reported the death of aqueous inocula of pathogenic Enterococcus faecalis or Enterococcus faecium isolates, simulating fomite surface contamination, in 1 h on copper alloys, compared to survival for months on stainless steel.
In our current study we observed an even faster kill of over a 6-log reduction of viable enterococci in less than 10 min on copper alloys with a “dry” inoculum equivalent to touch contamination. We investigated the effect of copper(I) and copper(II) chelation and the quenching of reactive oxygen species on cell viability assessed by culture and their effects on genomic DNA, membrane potential, and respiration in situ on metal surfaces.
We propose that copper surface toxicity for enterococci involves the direct or indirect action of released copper ionic species and the generation of superoxide, resulting in arrested respiration and DNA breakdown as the first stages of cell death. The generation of hydroxyl radicals by the Fenton reaction does not appear to be the dominant instrument of DNA damage. The bacterial membrane potential is unaffected in the early stages of wet and dry surface contact, suggesting that the membrane is not compromised until after cell death.
These results also highlight the importance of correct surface cleaning protocols to perpetuate copper ion release and prevent the chelation of ions by contaminants, which could reduce the efficacy of the surface.
Warnes, S.L. et al. 2012. Horizontal transfer of antibiotic resistance genes on abiotic touch surfaces: implications for public health. MBio 2012 Nov; 3(6):e00489-12. DOI:10.1128/mBio.00489-12.
“This study demonstrated that HGT readily occurs on dry touch surfaces such as stainless steel, providing a potentially important route for multidrug resistance emergence and dissemination in public buildings and transportation systems if surfaces are not regularly and efficiently cleaned…. The use of copper alloys in clinical and community settings could help reduce infection spread and also reduce the incidence of horizontal transmission genes conferring drug resistance, virulence, and pathogenesis and expression efficiency.”
The above is a small selection of papers from over 40 years of research into the intrinsic antimicrobial properties of copper and copper alloys.
Contact us for further scientific references or advice.