Interview with Prof Bill Keevil

Interview with Prof. C. W. Keevil, Head of the Environmental Healthcare Unit at University of Southampton’s School of Biological Sciences

Can copper help to stop the epidemic dissemination of diseases?

The prevention of diseases requires multiple barriers for effective control, particularly where resistance to therapeutic antibiotics is increasing. These barriers include preventative measures such as regular contact surface washing (e.g. work surfaces, door handles, push plates), hand washing (particularly the frequent use of alcohol-based handrubs by staff in hospitals to control MRSA spread) and prophylaxis (e.g. vaccination or antibiotic treatment). Unfortunately these measures are not completely effective – so additional barriers are required: the simplest, for example, is installing surfaces with inherent antimicrobial properties that remain effective with standard cleaning agents and procedures. Our work has shown that copper and some of its alloys are able to kill bacteria, fungal and viral pathogens within minutes or hours when they come into contact. By contrast, stainless steel and modern plastics do not show this useful property.

Can you tell us more about the Selly Oak Hospital clinical trial?

The first phase of hospital trials, at Selly Oak Hospital in Birmingham, UK, led by Prof. Tom Elliott, started in 2007. This involved random sampling of some of the copper surfaces at different time points compared to control items. Phase 2 of the testing involved a change in the design of the trial. The test ward was partitioned to form a Clostridium difficile cohort ward to create a real challenge for copper – an infection gradient between this area and the main ward.

Door push plates, taps and toilet seats were sampled at 2 time points on one day each week over 5 weeks. After the 5 weeks, the copper and control items were swapped over and tested for another 5 weeks. This unique ‘crossover’ technique was designed to eliminate potential bias caused by the items being used in different locations and so in different ways. The results – a 90–100% reduction in total contamination on the copper items versus the controls – are most encouraging.

What does the most recent scientific research say about new applications for copper in the healthcare environment?

Further exciting results also suggest a role for copper as an effective control barrier in reducing the spread of bird flu. The experiment consisted of placing 2 million active units of the Influenza A virus (a family to which the H5N1 virus belongs) on a C11000 (99.9% purity) copper sheet, as well as on a S30400 stainless steel sheet. On the stainless steel sheet, the number of infectious virus units fell to 500,000 in 24 hours, a reduction of 75%, whereas on the copper sheet, only 500 infectious virus units survived after six hours, i.e. a reduction of 99.9%. Copper’s ability to inactivate the flu virus means that these results are extremely interesting given current interest in curbing a potential bird flu epidemic.