Copper surfaces, using copper alloys such as brass and bronze, are being increasingly proposed for use in healthcare and other public settings due to their ability to rapidly kill bacteria on contact. Copper is man’s oldest metal and its medicinal use in the disinfection of chest wounds and drinking water is recorded in the Smith Papyrus, an ancient Egyptian medical text from the 2nd century BC; Charles Darwin used copper skins below the water line of The H.M.S. Beagle to extend the hull life by protecting against barnacles and other kinds of biofouling, and more recently the antimicrobial properties of copper surfaces have been firmly established in laboratory research.
Ironically it was the advent of commercially available antibiotics in the 1930’s that led to the decline in coppers medical application and since growing bacterial resistance to antibiotics in human medicine has led to the development of a number of difficult-to-treat healthcare associated infections (HAIs). The global danger posed by this public health challenge has been described the U.K.s Chief Medical Officer Professor Dame Sally Davies a ‘ticking time bomb’ rankable alongside terrorism on a list of threats to the nation.
Bacterial Resistance to Antibiotics is as seious as terrorismProfessor Dame Sally Davis
Novel environmental research reported in December 2012 by Professor Keevil from the University of Southampton has added to the renewed interest in the widespread applicability of antimicrobial copper. His team using fluorescent microscopy found that dry, clean copper surfaces when tested against a bacterial level usually found in hospitals demonstrated a kill time of 2 minute whereas stainless steel surfaces, which have no antimicrobial properties, prolonged bacterial survival for several weeks.
The main reason for antibiotic resistance is an innovative adaptive characteristic of bacteria called lateral gene transfer (LGT). Unlike the dominant pattern of hereditary descent or vertical transfer where genetic material is exchanged sexually, LGT enables microorganisms to partially exchange or horizontally transfer genetic material with each other so that antibiotic resistance is acquired without exposure to antibiotics. 80% of disease is spread by touch and LGT can take place between microorganisms on any frequently touched surfaces including toilet seats, taps and door handles etc., resulting in the spread of antibiotic resistance rates which have more than doubled in 5 years.
Dry copper can kill bacteria in 2 minutes, stainless steel allows bacteria to survive for weeks!
Copper is an essential trace metal vital to all organisms and crucial to proper organ and metabolic functioning but it also has toxic effects. While not fully understood the current, tentative state of knowledge is that contact killing occurs by succesive membrane damage, allowing a copper influx into cells, resulting in oxidative damage, cell death, and DNA degradation.
Bacterial survival on dirty, moist copper surfaces has been demonstrated but as yet bacterial resistance to copper has not been established on dry surfaces and its widespread appearance is considered unlikley because plasmid DNA is completely degraded after cell death by copper contact mediated killing which in itself is very rapid.
Copper is now registered at the US Environmental Protection Agency as the first solid antimicrobial material. The antibacterial efficacy of copper metals won’t wear away but actually increase with wear and tear and cleaning through a process called palination which results in slight discolouration. It is resistant to corrosion, effective even when scratched, and accessible, recyclable so sustainable and cost effective with widespread applications for its use in general public places such as airports, restaurants and possibly in drinking vessels in developing countries to reduce infection transmission such as cholera.
Bacterial resistance still account for 7% of all deaths in England, that’s 37.000 people annually, the same number that die in road related accidents.
Professor Keevil’s research has shown that replacing common touch surfaces with a copper alloy is cost effective and prevents the transmission of infection while reducing the spread of antibiotic resistance. However, this must be used in conjunction with standard infection control hygiene procedures including hand washing. Cases of methicillin-resistant Staphylococcus aureus, aka MRSA, have fallen by 80% since 2003 through improved hygiene measures in hospitals but Healthcare Associated Infections related to bacterial resistance still account for 7% of all deaths in England, that’s 37.000 people annually, the same number that die in road related accidents.
Globally we are running out of antibiotics, no new class of antibiotic have been developed since the late 1980’s so the pharmaceutical industry must be incentivised towards research and development and simply making new antibiotics. This is crucial or we may find that we face a return to a time pre antibiotics where infections kill us as a result of routine operations.