PR 543 - Antibacterial properties of copper and brass
combat toxic E.coli 0157 bacteria
A recent study by Dr. Bill Keevil* at the
Centre for Applied Microbiology & Research (CAMR) found that the highly toxic E.
coli O157:H7 strain of bacteria survive for much shorter periods of time on copper and
brass surfaces than on stainless steel. This finding has wide-ranging implications for
reducing outbreaks from cross contamination of E. coli in the food processing
industry.
The study also found that copper has significant antibacterial advantages over polybutylene plastic and stainless steel in cool potable "soft" waters. This finding indicates that copper water piping systems may help to reduce the risk of human infection from waterborne E. coli O157 bacteria in many drinking water systems around the world.
Copper and brass surfaces may reduce E. coli O157 outbreaks in food processing.
The results obtained at CAMR indicate that copper and brass food preparation surfaces have the potential to combat deadly E. coli O157 quickly and efficiently. Therefore, food preparation materials made from copper and brass may reduce the incidence of cross contamination of food products with toxic E. coli O157 bacteria.
The work carried out by team member Dr. Andrew Maule found that at room temperatures it takes 34 days for E. coli O157 bacteria to die on stainless steel tiles, 4 days to die on brass tiles, and just 4 hours to die on copper tiles. At chill temperatures typical of food storage, the study found that ten percent of the bacteria were still alive on stainless steel tiles after 34 days, whereas bacteria were completely eradicated on brass tiles within 12 days and on copper tiles in just 14 hours.
These results prompted the International Copper Association to commission CAMR researchers to further investigate the bactericidal properties of copper, brass, and stainless steel surfaces in various conditions found in the food preparation industry. For example, in acidic environments representative of fruit juice processing, E. coli O157 survived for as little as 45 minutes on copper, versus 2 days on stainless steel. And in
Environments containing animal faeces with anaerobic E. coli O157 bacteria, copper and brass tiles were found to exhibit superior bactericidal effects to stainless steel tiles.
"It may be possible to achieve important public health benefits just by changing the surface material commonly used in food processing," said Dr. Keevil. "Stainless steel is the most widely used surface in food preparation, but this material can remain a source of microbial food contamination for a very long period of time." Since copper-bearing materials have such strong antibacterial properties, the researchers believe that foods most amenable for processing on copper surfaces should be determined in order to reduce E. coli O157 occurrences and outbreaks.
"Our findings point to the potential use of copper and brass as hygienically beneficial surfaces in the food processing industry," said Keevil. "We now have a preliminary understanding of the bactericidal benefits of copper and brass over stainless steel in combating cross contamination from E. coli O157." Plans are under consideration to investigate the antibacterial effect of copper and brass on Salmonella enteritidis PT4, Campylobacter jejuni, S. typhimurium DT104, and other highly toxic bacteria.
Attached:
About Escherichia coli (E. coli) O157
Available if requested - graphs showing survival times of E.coli on copper, brass and stainless steel surfaces. Also available as a PDF File
Editorial Enquiries:
Angela
Vessey |
|
21st June 2000 |
PR543 |
About Escherichia coli (E. coli) O157
E. coli O157 is a highly infectious ACDP Hazard Group 3 foodborne and waterborne pathogen that has created a serious public health challenge for the food processing industry. This strain of bacteria produces potent verocytotoxins, which can cause haemolytic colitis, haemolytic uraemic syndrome (kidney disease), and even death.
E. coli O157 bacteria infect tens of thousands of people around the world every year. An outbreak in Japan caused 9,000 people to become sick. A 1997 outbreak in Scotland was responsible for 500 infections and 20 deaths. And in the U.S., over 500 people became ill and three children died after eating undercooked hamburgers infected with E. coli O157.
It is believed that just ten to fifty highly toxic E. coli O157 organisms are sufficient to infect humans with illness. The infections are difficult to treat and antibiotics may prompt the bacteria to release even more verocytotoxins. In healthy individuals, E. coli O157 infections usually last three to five days. However, the bacteria can victimise children under 14 years of age, the elderly, and immunocompromised individuals with serious complications.