Antimicrobial Properties of Copper

Historic Uses of Antimicrobial Copper

brass vesselTypical brass mutka from rural Rajasthan, India
Copper and its alloys (brasses, bronzes, copper nickels, copper nickel zincs, and others) are naturally antimicrobial materials. Man exploited the antimicrobial attributes of copper long before the nineteenth century, when Louis Pasteur developed the germ theory of disease which states that infections are caused by microbes invading the human body. The Hippocrates Collection, 460 to 380 B.C., to which the father of medicine contributed, recommends the use of copper for leg ulcers related to varicose veins. Pliny, 23 to 79 A.D., used copper oxide with honey to treat intestinal worms. The Aztecs gargled with a mixture containing copper to treat sore throats. In a laboratory study, water inoculated with the fecal indicator bacterium Escherichia coli was stored in brass (a copper alloy) water vessels traditionally used in rural India, as well as in earthenware vessels. The vessels contained distilled water or natural water from the Punjab region in rural India. No live bacteria were found in the brass vessels after 48 hours, while the water in the earthenware vessels remained contaminated. In an earlier study, brass doorknobs in a hospital showed sparse growth of pathogenic bacteria, while stainless steel doorknobs were heavily contaminated.

Today, Hospital Infection Control is a Key Issue

The Centers for Disease Control and Prevention (CDC) estimate that more than 2 million patients contract a hospital acquired infection each year in the USA, resulting in nearly 90,000 deaths. In March of 2009, the CDC estimated direct hospital medical costs to be $35-45 billion.

Common hospital materials – stainless steel and plastics – are colonized by microbes that can persist for days or weeks thereby becoming a source of contamination to hands and equipment of healthcare workers, professionals, visitors and the patients themselves. 

MSKCC ICU RoomICU room

The CDC's recommended practices of washing hands before and after seeing patients is sound and necessary, along with the wiping and disinfecting of all touch surfaces.  However, the intrinsic antimicrobial properties of copper and copper alloys (brasses and bronzes) for hospital hardware and equipment add another layer of continuous protection against a wide range of pathogens and multi-drug resistant bacteria such as Methicillin-resistant staphylococcus Aureus (MRSA), Eschericia coli 0157:H7, Pseudomonas aeroginosa, and Enterobacter aurogenes, thereby complementing the practical CDC guidelines and practices.

Copper railsCopper rails

A multi-year study funded by the Telemedicine and Advanced Technology Research Center, US Army Medical Research and Materiel Command is showing the beneficial effect of copper surfaces in the reduction of microbial burdens, as compared to non-copper surfaces.  This study involves the evaluation of three specific bacterial pathogens: Methicillin-Resistant Staphylococcus aureus (MRSA); vancomycin-resistant Enterococci (VRE), and Staphylococcus aureus, along with total gram negatives and total bacteria; and three different medical facilities focused on three distinct patient populations.  The hospital centers are Medical University of South Carolina (MUSC), Memorial Sloan-Kettering Center, and Charleston Research Institute at the Ralph H. Johnson VA Medical Center. This study:

  • Introduced copper touch surfaces and measured their positive effect at reducing the levels of harmful microbes;
  • Is measuring how the bioload reduction in the hospital environment may improve clinical outcomes; and
  • Demonstrated that the inherent antimicrobial effects of copper and its alloys can augment recommended CDC practices.

Resources:

Telemedicine and Advanced Technology Research Center, US Army Medical Research and Materiel Command, 2009 Annual Report, pps 126-127. Complete report is available on TATRC site.