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Copper could help keep Africa clean

August 8, 2006 By Natasha Bolognesi This article courtesy of Nature News.

Programme aims to use metal taps and work tops to kill hardy bacteria.

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In Africa's ongoing struggle against tuberculosis, a group of scientists and industry representatives are now exploring a plan to introduce copper pipes, doorknobs and work surfaces to the country's waterways and clinics. The metal's known antibiotic activity, they say, could provide a simple way to help fight the deadly infection.

Past research has shown that copper has strong anti-bacterial properties against worrisome pathogens such as the superbug MRSA. Whereas all cells need a bit of copper to grow, an excess can overwhelm a cell's mechanism to bind to the metal, effectively killing it from over-exertion. Recent work by scientists from the University of Southampton, UK, showed that MRSA was unable to survive on copper alloy surfaces for longer than 90 minutes1.

Recent research from a team in South Africa shows that copper also wipes out the bacterium responsible for tuberculosis (TB) one of Africa's biggest killers. The researchers, from the University of Stellenbosch, presented their data last month at a meeting of the International Federation of Infection Control (IFIC), held in Stellenbosch from 3-5 July.

Laboratory tests showed that after 48 hours of exposure, pure copper and five of its alloys could inhibit growth in TB bacteria, including strains resistant to usual drugs, with no signs of regrowth over the study period of 15 days.

TB is an extremely resilient bug, says Shaheen Mehtar, who headed the research. It often grows back on, say, a stainless-steel surface that has been cleaned with disinfectant, after just a couple of days. "So the copper results are promising," she says.

Such results have spurred ideas to make hospital surfaces from copper alloys, to help keep background levels of infectious bacteria down. A trial is currently being run by Takeshi Sasahara at the Japanese Kitasato University Hospital. Sasahara says that the simple change has resulted in a "consistent and significant reduction" in surface contamination by Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Whether it is the best way to keep bugs in check, however, is still up for debate, he says.

Killer metal

Ben Marais, a paediatrician at Stellenbosch University, notes that it can take up to 6 hours for copper to kill bacteria, so there remains a window of opportunity when infection can occur. And TB is transmitted by the inhalation of airborne bugs, so self-sanitizing surfaces might not have as big an impact as hoped with that disease. But, he adds, reducing the chance of infection in a country such as South Africa, where an estimated 5.3 million people live with HIV and are particularly vulnerable to opportunistic infections, "may be of great benefit".

Gerhard Offringa, from the South African Water Research Commission, says that full water treatment systems are obviously better than copper alone, as they are designed to address a number of potential problems with the water supply. But he adds that "It's good to have a back-up system. Rural water-treatment systems are not always correctly monitored. Here copper would be a good additional barrier."

Representatives from the International Copper Development Association, along with African industry participants, engineers and faculty from the Stellenbosch University, gathered at a workshop in Johannesburg immediately after the IFIC conference to plan how best to use copper to fight disease in Africa.

Project manager Grant Mackintosh says they are still at the planning stage, but adds that at least one trial will begin before the end of the year at the Kayamandi township clinic outside Stellenbosch.

"Copper is not the answer for everything," says Mackintosh. "But what we are looking at here is copper's role in making a significant contribution."

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References

  1. Noyce J. O., Michels H.& Keevil C. W. . J. Hosp. Infect., 63. 289 - 297 (2006).

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