Scientists at the University of Southampton are part of an international research drive to develop the bacteria-killing properties of copper, a metal first used by the ancient Egyptians to keep water fresh.

The University team is led by Professor Bill Keevil, who has already shown that E. coli O157 can survive for months on stainless steel, the work surface used in most commercial kitchens.

At the chill temperature typically used for food storage (39F) the bug, traced to thousands of cases of virulent food poisoning worldwide, survived for more than 35 days, and sometimes for as long as three months. There were no surviving organisms on brass after 12 days or on copper after 14 hours.

At room temperature of 20 degrees Celsius (68F), the bacteria survived on stainless steel for 34 days, on brass for four days and on copper for just four hours.

Professor Keevil said: "Stainless steel is used throughout the world because of its perceived hygienic properties. It always looks like a nice, clean and bright surface.

"But a closer look reveals scratches and marks which, on a microscopic scale, are more like valleys. It is very easy for pathogens to get into these crevices and rubbing a cloth or brush across the surface may not be sufficient to get them out. Unless a good disinfectant is used to get to the bottom of the valley, you can't kill them off."

It is recognized that cross-contamination in food preparation is a major problem. At-risk areas range from butcher shops to restaurants, from hospitals to the home. In 1997, an outbreak of E. coli O157 in Scotland made 500 people ill and killed 20.

The International Copper Association, based in New York, is now working with the University looking at whether copper is as effective in killing newly emerging strains of the bug.

Professor Keevil added: "The research we have already done has shown that E. coli O157 is a very robust pathogen and that very rigorous cleaning techniques are needed to try and keep it out of the food chain.

"The goal is now to find the appropriate copper alloys that are acceptable for food use, easy to maintain, economical to fabricate and which retain the ability to kill bacteria.

"If this work is successful, it may be possible to achieve important public health benefits just by changing the surface material commonly used in food processing."

Professor Keevil is a Fellow of the American Academy of Microbiology and the Institute of Biology.

The University of Southampton is a leading UK teaching and research institution with a global reputation for leading-edge research and scholarship. The University has 20,000 students and over 4,500 staff and plays an important role in the City of Southampton. Its annual turnover is in the region of £200 million.

The International Copper Association is not only committed to studying the effects of copper in reducing pathogens, but is also taking a closer look at the health benefits of "dietary" copper, including its positive role in fetal development, osteoporosis, neurodegenerative diseases and cardiovascular disease.

[Contact: Professor Bill Keevil, Kim d'Arcy]

21-Aug-2001