Copper, like silver, kills bacteria mechanically. Because of this the microbes cannot develop a resistance to it. The exact mechanism by which copper kills bacteria is still being researched, however, several theories exist and are being studied. They include:
- a leakage of potassium or glutamate through the outer membrane of bacteria
- a disturbance in osmotic balance
- the ability of copper to bind to proteins that do not require copper
- the oxidative stress caused by generating hydrogen peroxide
non-disposable metal or plastic surfaces on door knobs, railings and tray tables are often touched by people in hospitals and clinics, becoming sources of infection.
Researchers at the Memorial Sloan Kettering Cancer Centre, New York, the Medical University of South Carolina and the Ralph H. Johnson VA Medical Centre, replaced bed rails, overbed tray tables, nurse call buttons and IV poles with antimicrobial copper versions according to a Sloan Kettering statement. Data presented by trial leader Michael Schmidt, professor of microbiology and immunology at Sloan Kettering, demonstrated a 97 per cent reduction in surface pathogens in rooms with copper surfaces.
Schmidt said: " Bacteria present on ICU room surfaces are probably responsible for 35-80 per cent of patient infections, demonstrating how critical it is to keep hospitals clean."
"The copper objects used in the clinical trial supplemented cleaning protocols, lowered microbial levels, and resulted in a statistically significant reduction in the number of infections contracted by patients treated in those rooms," he said.
Laboratory testing shows that, when cleaned regularly, Antimicrobial Copper kills greater than 99.9% of the VRE, MRSA, Staphylococcus aureus, Enterobacter aerogenes, Pseudomonas aeruginosa, and E. coli O157:H7. Antimicrobial Copper surfaces are a supplement to and not a substitute for standard infection control practices and have been shown to reduce microbial contamination, but do not necessarily prevent cross contamination; users must continue to follow all current infection control practices.
Michels et al, Lett Appl Microbiol, 49 (2009) 191-195 demonstrated that Antimicrobial CopperTM outperforms two commercially available silver-containing coatings under typical indoor conditions.