Biocidal Mechanisms of Metallic Copper Surfaces - Use of Biocidal Surfaces for Reduction of Healthcare Acquired Infections - page 102

Abstract Hospital acquired infections (HAI), also known as nosocomial
infections, have a vast impact on patient and staff health and affect survival chances
of patients with compromised immune system, elderly, and young children. More-
over, hospital environments are favoring the development of drug-resistant strains
of bacteria, making treatment of such HAI more challenging. The Center of Disease
Control estimates that one of the deadliest types of antibiotic-resistant bacteria,
MRSA (methicillin-resistant Staphylococcus aureus ), causes 19,000 death cases
per year, whereas another superbug, Clostridium difficile , causes 500,000 incidents
per year.
The natural medicinal and sanitizing properties of copper and its minerals were
used throughout the ages by many civilizations. However, only recently have we
started understanding the mechanisms of such bactericidal effects of copper. One of
the latest research developments in this area is concerned with showing that metallic
copper surfaces strongly reduce microbial surface-burden, both in laboratory settings
and healthcare environments. Microbiologists and hygiene specialists are increas-
ingly recognizing this unique antimicrobial property of metallic copper as a very
promising novel tool for reducing HAI, which are known to spread through touching
contaminated surfaces. Copper surfaces have universal microbe-inactivating
properties against a wide variety of Gram-positive and Gram-negative microbes
under moist (droplets of cell suspensions, mimicking splash-contamination) or dry
(direct contact between cells and surfaces, mimicking touch surfaces) conditions.
This chapter reviews the molecular mechanisms underlying bactericidal prop-
erties of solid copper surfaces and factors that influence such processes: copper
surface oxidation and corrosion, copper cell accumulation, copper alloy content and
roughness, temperature, moisture, presence of chelators, osmotic stress, reactive
oxygen species, cellular characteristics, cell wall structure, spores, genetic traits for
copper resistance systems, anaerobiosis, viable but not culturable state (VBNC).
Additionally, primary targets for metallic copper toxicity, DNA and lipids, are also
included in discussion in this chapter.
Our understanding of the antimicrobial properties of metallic copper surfaces
have made great strides in the last 5 years both under laboratories and healthcare
conditions, highlighting safe, economical and sustainable application of metallic
copper surfaces in hospital or any public settings for prevention of HAI.

Keywords Metallic copper surface ￿ Antimicrobial ￿ Biocidal ￿ Toxicity ￿ Killing
mechanism ￿ Membrane damage ￿ Genotoxicity

List of Abbreviations

BCS Bathocuproine disulfonate

BTA Benzotriazole

C-C ￿

C ¼ Allylic radicals

CFU Colony forming units