Germ Warfare

Walk down the household products aisle of any supermarket and "anti-bacterial" labels vie for your attention. There are soaps, lotions, cleaners, wipes; even chopping boards and toys. The word plays on our fear of germs - the flesh-eating, disease-carrying bugs that feature in sci-fi thrillers and best-sellers. But how well do anti-bacterials protect us?

Milder detergents, like soap and water, are effective at removing bacteria on hands or work surfaces before they reach a dangerous level, but anti-bacterials can wipe out all organisms, many of which play a useful role. Some "good" micro-organisms fight germs, for example by chewing up bits of protein and dried milk, cleaning the surface of these nutrients. If benign bacteria are killed off, experts believe, dangerous cells - such as those on raw chicken - will be free to multiply.

Professor Vanya Gant, a microbiologist at University College London Hospitals Trust, says germ-busting products could be upsetting a natural equilibrium. "It's a basic principle that if you have something sterile then whatever is around will grab hold. In the kitchen that may be 'nice' bugs but it may be 'nasty' bugs. If you are sensible about these things then you achieve some kind of balance."

But anti-bacterials could be contributing to a damaging trend. According to the "hygiene hypothesis", excessive cleaning is the key to why certain conditions are on the increase - among them asthma, eczema and hay fever, as well as more serious diseases such as multiple sclerosis and ulcerative colitis. The theory is that when common germs are killed off in the environment, the immune system is not exposed to them, so it has no appropriate response when they do appear. Studies show that children brought up in less hygiene- conscious households are not as likely to develop allergic reactions.

Another concern is that the increased use of anti-bacterials may have links with resistance to antibiotics - now a major problem in medicine. Research is at an early stage, but scientists have found that certain household chemicals select antibiotic-resistant strains of bacteria, killing sensitive organisms while resistant ones survive.

"In the laboratory you can show that the exposure to some types of products can result in the selection of antibiotic-resistant bacteria," notes Denver Russell, professor of pharmaceutical microbiology at the Welsh School of Pharmacy, who has studied resistance to the antibiotics Methicillin and Vancomycin.

Research in the US also suggests that "superbugs" could emerge, which are resistant to anti-bacterials in environments like hospitals, where they are essential. A study at Tufts University School of Medicine in Boston tested the popular anti-bacterial Triclosan on E. coli bacteria and found that the chemical targets a particular bacterial gene. Although bacteria resistant to Triclosan have not yet been found, scientists concluded that the potential for developing such a strain is high because of the increasing use of Triclosan in the home.

But while the fears connected to anti-bacterials are mainly theoretical, the bugs they are intended to kill do pose a real threat. Conditions in factory-farmed animals - particularly battery hens - mean infections like salmonella, E. coli and campylobacter are rife in Britain. Around 90 per cent of chickens are contaminated with campylobacter, the most common cause of food poisoning, which generally makes victims ill for a week or more.

Scientific consultant John Pickup says that while mild anti- bacterials are little better than other detergents, a good product, used sparingly on work surfaces, will wipe out damaging organisms, creating a safe environment for food preparation. "For food hygiene purposes, the products that are most useful are the ones that will kill bacterial contamination," he argues, adding that many anti- bacterials have been around for decades without the development of resistant strains. "These products have been in widespread use for 70 or 80 years in hospitals. If people abuse them you do get temporary susceptibility, but the minute you put things straight everything goes back to normal."

But in the home, a better strategy may be to eliminate conditions in which organisms such as campylobacter can breed. Prof Graham Rook, a medical microbiologist at the Royal Free and University College Medical School recently pioneered the "dirt vaccine" with his colleague John Stanford, to help asthma sufferers. He believes the real hygiene problem is not in the home, but in the food supply. "We don't want to have dysentery or diarrhoea, so it does make sense to protect ourselves from those," he says. "We do that by keeping the law tight on food suppliers, so food suppliers don't supply us with dangerous foods" Concern is growing about possible adverse effects of anti-bacterial products - but some believe they could be the best way to suppress disease

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