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Research on the antiviral and antibacterial properties of copper, as well as its possible application on surfaces for disease prevention

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Abstract

Copper has been identified for its antimicrobial properties, killing bacteria, viruses, and yeast when in contact. Scientific evidence gathered shows that the use of copper on surfaces reduces significantly the number of bacteria in the surrounding environment. This paper reviewed the importance of copper on living organisms, applications through history revealing antimicrobial properties, as well as possible applications in the medical field.
Published online May 19, 2020 doi: 10.6084/m9.figshare.12331208
Research on the antiviral and antibacterial properties of copper,
as well as its possible application on surfaces for disease
prevention.
Andrea ROSS-OROZCO
Abstract
Copper has been identified for its antimicrobial properties, killing bacteria, viruses, and yeast
when in contact. Scientific evidence gathered shows that the use of copper on surfaces reduces
significantly the number of bacteria in the surrounding environment. This paper reviewed the
importance of copper on living organisms, applications through history revealing antimicrobial
properties, as well as possible applications in the medical field.
Keywords: copper; antimicrobial; antivirus; nanotechnology; disease prevention
1 Introduction
Copper has accompanied humanity since
its inception, since it is one of the metals that,
in low concentrations, are essential for the
metabolism of animal and plant cells; it plays
a role in making red blood cells and it helps
maintain healthy bones, blood vessels, nerves,
and immune function, and it contributes to iron
absorption (Ware, 2017)
Its properties to prevent infections were
recognized since ancient times. The oldest
recorded medical use of copper is mentioned
in the Smith Papyrus, written between 2600
and 2200 B.C. It describes the use of copper to
sterilize wounds, water, and to heal headaches,
burns, infections, and intestinal worms (Grass
et al., 2010, p. 1546).
In the last decade, the concept of copper as
an antimicrobial has been revitalized, caused
by the spread of antibiotic-resistant bacteria in
hospitals, food processing plants, and animal
breeding facilities. (Prado J. et al., 2012, p.
1330).
2 Evidence of the antimicrobial capacity
of copper.
Research conducted in 2005 has shown
that copper surfaces or their alloys are capable
of eliminating 99.9% of pathogenic bacteria
within hours. In said research, a copper surface
eliminated methicillin-resistant Staphylococc-
us aureus (MRSA) in 90 minutes; while with
stainless steel no decrease in bacterial
concentration was observed after 6 hours (360
minutes). In the bronze alloy, which contains
80% copper, the MRSA was eliminated in 270
min (Wilks, Michels, & Keevil, 2005, p. 451).
Another experiment with Pseudomonas
aeruginosa strains have shown a synergistic
effect between copper cations, Cu2 + and
quaternary ammonium disinfectants, to exert
bactericidal action on this pathogen that has
special ability to survive in environments with
a low concentration of nutrients and a
minimum of humidity.
Antiviral and antibacterial properties of copper
2
Laboratory evidence documents the
efficacy of copper in eliminating spores and
vegetative forms of Clostridium difficile, a
hospital pathogen associated with outbreaks of
nosocomial infections with high mortality.
These studies showed spore elimination after
24 hours of exposure to metallic copper; and
another study shows that this effect occurs
after 30 min for vegetative forms and at 3 h for
spores, even in the presence of organic matter.
It is important to note that the bactericidal
effect of copper surfaces is directly related to
concentration, the maximum effect being for
metallic copper (99.9%) and it is maintained in
alloys that contain at least 70% copper.
Backed by accumulated scientific
evidence, on March 25, 2008, the EPA
registered copper as the first and only metal
with antibacterial properties, authorizing the
dissemination of important concepts, inclu-
ding that "copper surfaces eliminate 99.9% of
bacterial pathogens after 2 hours of exposure"
and certifying that metallic copper surfaces
and their alloys are natural antimicrobials,
have long-lasting antimicrobial efficacy, have
a self-disinfecting effect and are superior to
other coatings available on the market. This
registry authorizes the use of copper surfaces
in hospital environments.
3 How does copper kill bacteria?
This is a question that still has no concrete
answer. Rodrigo Palma, a researcher at
Navarra University developed a hypothesis on
how copper acts on bacteria. He proposed that
copper leaves its structure or alloys in the form
of cations (Cu+), which are the positive ions
that are introduced into bacteria.
"What we are guessing is that the process is
similar to the corrosion of copper, in which
case mass is also lost. Therefore, at first sight,
we can think that as the alloy or the material
itself is more prone to corrosion, the greater its
bactericidal power,said Palma.
Other studies suggest that copper, in high
concentrations, has a toxic effect on bacteria
due to the release of hydroperoxide radicals,
copper ions could potentially replace ions
essential for bacterial metabolism such as iron,
initially interfering with the function of the cell
membrane and then at the level of the
cytoplasm altering protein synthesis, either
inhibiting protein formation or causing the
synthesis of dysfunctional proteins, altering
the activity of enzymes essential for bacterial
metabolism.
4 Antiviral activity
Copper has also demonstrated the ability to
destroy viruses of great medical importance,
including influenza and human immune-
deficiency virus, HIV, in concentrations as
low as 0.16 to 1.6 mM. The development of
copper oxide filters has efficiently eliminated
the risk of HIV transmission through fluids
(Borkow, 2008). The mechanisms involved in
antiviral activity are the inactivation of a
protease enzyme important for viral
replication and damage at the phospholipid
envelope level (Karlström, 1991).
5 Antifungal activity
Different species of fungi, among them
Candida albicans, an important pathogen in
immunosuppressed patients, are inhibited in
their growth and then destroyed, in contact
with copper surfaces. Recent studies indicate
that antifungal activity occurs through a
complex process called "contact death" in
which damage to the cytoplasmic membrane
occurs, which is depolarized; it is unclear
whether the damage affects the proteins or
lipids of the membrane. This facilitates the
entry of copper ions into the cell, amplifying
Antiviral and antibacterial properties of copper
3
the damage and, secondarily, an increase in
oxidative stress occurs, without appreciating
apparent damage to the DNA of these cells
(O157, 2005).
5 Possible applications
Lab trials have shown a reduction in
bacterial counts, indicating that copper
surfaces are a promising additional tool
alongside other hygienic measures to curb the
number and severity of hospital-acquired
infections. At this point, additional studies
would help determine the most cost-effective
way to give maximal protection in hospitals
(Grass et al., 2010, p. 1546). Highly
frequented sites should be made of copper e.g.,
doorknobs, faucets, and bed rails.
6 Conclusion
The antimicrobial properties of copper
surfaces have now been firmly established.
The antimicrobial properties of copper
surfaces must be integrated with other
methods of disinfection and the overall
hygiene concept of a health care facility.
Additional measures, such as the addition of
spore germinants to cleaning solutions to
improve the killing of spores, also deserve
further investigation.
7 References
Borkow, G. (2008, febrero 1). Deactivation of
Human Immunodeficiency Virus Type 1 in
Medium by Copper Oxide-Containing Filters.
https://aac.asm.org/content/52/2/518.short
Grass, G., Rensing, C., & Solioz, M. (2010).
Metallic Copper as an Antimicrobial
Surface. Applied and Environmental
Microbiology, 77(5), 1541-1547.
https://doi.org/10.1128/aem.02766-10
Karlström, A. R. (1991, julio 1). Copper
inhibits the protease from human
immunodeficiency virus 1 by both cysteine-
dependent and cysteine-independent
mechanisms.
https://www.pnas.org/content/88/13/5552.sho
rt
Prado J, V., Vidal A, R., & Durán T, C. (2012).
Application of copper bactericidal capacity in
medical practice. Medical Journal of Chile,
140,1325-1332. https://doi.org/10.4067/
s0034-98872012001000014
The survival of Escherichia coli O157 on a
range of metal surfaces. (2005, diciembre 15).
https://www.sciencedirect.com/science/article
/abs/pii/S0168160505003466
Ware, M. R. (2017, octubre 23). Copper:
Health benefits, recommended intake, sources,
and risks. https://www.medicalnewstoday
com/articles/288165#effects_of_deficiency
Wilks, S. A., Michels, H., & Keevil, C. W.
(2005). The survival of Escherichia coli O157
on a range of metal surfaces. International
Journal of Food Microbiology, 105(3), 445-
454.
https://doi.org/10.1016/j.ijfoodmicro.2005.04.
021
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Full-text available
Article
Escherichia coli O157:H7 is a serious pathogen causing haemorrhagic colitis. It has been responsible for several large-scale outbreaks in recent years. E. coli O157:H7 is able to survive in a range of environments, under various conditions. The risk of infection from contaminated surfaces is recognised, especially due to the low infectious dose required. In this study, a high concentration (107 cells) of E. coli O157 was placed onto different metals and survival time measured. Results showed E. coli O157 to survive for over 28 days at both refrigeration and room temperatures on stainless steel. Copper, in contrast, has strong antibacterial properties (no bacteria can be recovered after only 90 min exposure at 20 °C, increasing to 270 min at 4 °C) but its poor corrosion resistance and durability make it unsuitable for use as a surface material. Other copper-containing alloys, such as copper nickels and copper silvers, have improved durability and anticorrosion properties and greatly reduce bacterial survival times at these two temperatures (after 120 min at 20 °C and 360 min at 4 °C, no E. coli could be detected on a copper nickel with a 73% copper content). Use of a surface material with antibacterial properties could aid in preventing cross-contamination events in food processing and domestic environments, if standard hygiene measures fail.
Full-text available
Article
Bacteria, yeasts, and viruses are rapidly killed on metallic copper surfaces, and the term "contact killing" has been coined for this process. While the phenomenon was already known in ancient times, it is currently receiving renewed attention. This is due to the potential use of copper as an antibacterial material in health care settings. Contact killing was observed to take place at a rate of at least 7 to 8 logs per hour, and no live microorganisms were generally recovered from copper surfaces after prolonged incubation. The antimicrobial activity of copper and copper alloys is now well established, and copper has recently been registered at the U.S. Environmental Protection Agency as the first solid antimicrobial material. In several clinical studies, copper has been evaluated for use on touch surfaces, such as door handles, bathroom fixtures, or bed rails, in attempts to curb nosocomial infections. In connection to these new applications of copper, it is important to understand the mechanism of contact killing since it may bear on central issues, such as the possibility of the emergence and spread of resistant organisms, cleaning procedures, and questions of material and object engineering. Recent work has shed light on mechanistic aspects of contact killing. These findings will be reviewed here and juxtaposed with the toxicity mechanisms of ionic copper. The merit of copper as a hygienic material in hospitals and related settings will also be discussed.
Full-text available
Article
Human immunodeficiency virus type 1 (HIV-1) can be transmitted through breast-feeding and through contaminated blood donations. Copper has potent biocidal properties and has been found to inactivate HIV-1 infectivity. The objective of this study was to determine the capacity of copper-based filters to inactivate HIV-1 in culture media. Medium spiked with high titers of HIV-1 was exposed to copper oxide powder or copper oxide-impregnated fibers or passed through copper-based filters, and the infectious viral titers before and after treatment were determined. Cell-free and cell-associated HIV-1 infectivity was inhibited when exposed to copper oxide in a dose-dependent manner, without cytotoxicity at the active antiviral copper concentrations. Similar dose-dependent inhibition occurred when HIV-1 was exposed to copper-impregnated fibers. Filtration of HIV-1 through filters containing the copper powder or copper-impregnated fibers resulted in viral deactivation of all 12 wild-type or drug-resistant laboratory or clinical, macrophage-tropic and T-cell-tropic, clade A, B, or C, HIV-1 isolates tested. Viral inactivation was not strain specific. Thus, a novel means to inactivate HIV-1 in medium has been developed. This inexpensive methodology may significantly reduce HIV-1 transmission from "mother to child" and/or through blood donations if proven to be effective in breast milk or plasma and safe for use. The successful application of this technology may impact HIV-1 transmission, especially in developing countries where HIV-1 is rampant.
Application of copper bactericidal capacity in medical practice
  • J Prado
  • V Vidal
  • R Durán
https://www.pnas.org/content/88/13/5552.sho rt Prado J, V., Vidal A, R., & Durán T, C. (2012). Application of copper bactericidal capacity in medical practice. Medical Journal of Chile, 140,1325-1332. https://doi.org/10.4067/ s0034-98872012001000014
Copper: Health benefits, recommended intake, sources, and risks
  • M R Ware
Ware, M. R. (2017, octubre 23). Copper: Health benefits, recommended intake, sources, and risks. https://www.medicalnewstoday com/articles/288165#effects_of_deficiency