Scientific Evidence

The evidence presented here is based on trials done in the UK primarily in the University of Southampton, School of Biological Sciences by Professor Bill Keevil and in The University Hospital Birmingham NHS Foundation Trust by Professor Tom Elliott.

Presented at Materials Science and Technology Conference, September 25-28, 2005, Pittsburgh, PA

Copper for the 21st Century Symposium

Copper Alloys for Human Infectious Disease Control
H.T. Michels1; S.A. Wilks2; J.O. Noyce2; and C.W. Keevil2
1Copper Development Association Inc., USA
2University of Southampton, School of Biological Sciences, Environmental Healthcare Unit, UK

Several bacteria, known to be human pathogens, die when placed on copper alloy surfaces. The concentration of live bacteria drops from several orders of magnitude to zero on copper alloys in a few hours. In marked contrast, no reduction is seen in the concentration of live organisms on stainless steel during the six-hour test period. The copper alloys tested include high coppers, brasses, bronzes, copper -nickels and copper-nickel-zincs. The bacteria tested include E. coli O157:H7 and Listeria monocytogenes, both food-borne pathogens associated with several large-scale food recalls, and Methicillin-Resistant Staphylococcus aureus (MRSA), a serious hospital-acquired infection. The study results suggest the selection of copper alloys for surfaces exposed to human touch or food contact. Using copper alloys in this manner can materially assist in reducing the transmission of potentially infectious organisms.

The focus of the present study is on the inhibitory effects of the surfaces of a range of commercial wrought copper-base alloys, on bacteria, with stainless steel as an experimental control. The tested organisms include E. coli O157:H7 and Listeria monocytogenes, which are food-borne pathogens associated with several large-scale food recalls, and Methicillin-Resistant Staphylococcus aureus (MRSA), a serious hospital-acquired, or nosocomial infection. According to the March 28, 2001 issue of the New York Times, 76 million illnesses associated with contaminated food were reported annually in the United States, which resulted in 325,000 hospitalizations and 5000 deaths. Although most E. coli strains are harmless to humans, the U.S. Dept. of Agriculture (USDA) estimates that the cost to society associated with infectious strains of E. coli is $5 billion annually. The Centers for Disease Control (CDC) reported in 1999 that L. monocytogenes accounts for the highest hospitalization rate (90%) and the second highest fatality rate (20%) of all food-borne human pathogens. On average, there are 2,500 cases of L. monocytogenes reported each year and they result in 500 fatalities. According to a July 2004 report by the Infectious Disease Society of America, two million people are infected each year while in the hospital, and 70% of those infections are resistant to at least one drug. This resulted in 90,000 deaths and a cost to society of $5 billion annually.
According to the CDC, the growth rate of antibiotic-resistant bacterial infection is increasing.

Copper for preventing Microbial Environmental contamination

AL Casey,1 PA Lambert,2 L Miruszenko,1 TSJ Elliott.1
1 University Hospital Birmingham NHS Foundation Trust, Birmingham, UK
2 Aston University, Birmingham, UK

Trial run by Dr Tom Elliott, Deputy Medical Director and Consultant Microbiologist, at University Hospitals Birmingham NHS Foundation Trust.

Transmission of infection involves various vehicles, including contaminated surfaces which have stimulated interest in antimicrobial materials. Copper has antimicrobial activity and its application in the clinical setting has been explored. Activity of copper against a wide range of hospital pathogens was also determined.

Methods

In vitro activity - Microorganisms were applied to copper and stainless steel and viability determined over 3 hours at room temperature following their recovery into a universal neutralising solution. Viability on the metal was also determined by direct observation using epifluorescence microscopy of propidium iodide/SYTO 9 stained cells. Clinical assessment - A pilot study assessed the number of microorganisms on copper containing toilet seats, grab rails, tap handles, light switches and door push plates on a busy medical ward. The copper-containing items harboured fewer microorganisms than standard items on a control ward (p=0.01). The study design was adjusted to sample copper-containing and control items on the same ward. A copper-containing: toilet seat, set of tap handles and a ward entrance door push plate were sampled and compared against equivalent standard items.

Results

In vitro activity - The viability of Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumanii, Enterococcus spp. and Candida albicans was progressively reduced by at least 3 log 10 cycles over 3 hours on copper but not stainless steel surfaces. Clinical assessment - All copper-containing items harboured significantly fewer microorganisms (90%-100%) than their control equivalents.

Conclusions

Copper surfaces exhibit a pronounced antimicrobial action upon a range of pathogens, reducing viability over 3 hours contact at room temperature. Antimicrobial activity was also evident over a period of several months in the clinical setting. Copper surfaces may therefore, be a valuable tool in preventing nosocomial infection.