The healing power of germ warfare
Using yogourt's good bacteria to fight infection could spell an end to antibiotics
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Brad Evenson |
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National Post If the science of probiotics
...yogurt could replace many pharmaceutical drugs. |
For 2,000 years, people have known yogourt is good for you.
But even devotees of fermented milk's healing properties would be leery of what Gregor Reid and Bing Gan are up to these days.
Just over a year ago, the Canadian scientists injected trillions of lactobacilli -- bacteria found in some yogourt -- into some infected wounds.
"I know it sounds like a crazy idea, but we thought, 'let's give it a whirl,' " says Reid, a professor of immunology at the University of Western Ontario in London.
Actually, it was not exactly crazy. It was based on a century-old field now known as probiotics -- the idea that friendly bacteria can suppress the activity of harmful germs. The theory was first proposed by microbiologist Eli Metchnikoff at the Pasteur Institute in Paris, who noted the longevity of Bulgarian peasants who ate a lot of yogourt. Metchnikoff's subsequent research won him a Nobel Prize in 1907.
In recent years, probiotics has launched a new field of "functional foods" such as medicinal cheese than can treat urinary tract infections.
Still, using live germs to heal a festering wound seemed a bit far-fetched.
So when Reid and Gan, a plastic surgeon, opened up the lab rats' wounds four days after injecting them with lactobacilli, they were overwhelmed by what they saw. "We couldn't believe it, there was no infection whatsoever," said Reid.
"And we said, 'Holy Jesus, what happened?' "
When the researchers peered through a microscope, they saw the harmful Staphylococcus aureus germs that caused the infection -- which are resistant to almost all antibiotic drugs -- were not dead; they had simply stopped multiplying.
The scientists presented their data at a U.S. conference in December. The respected journal Science pounced on the findings immediately, with an article titled "Fighting Bacterial Fire with Bacterial Fire."
If the science holds up in human clinical trials, which are now under way, a spoonful of yogourt could replace many pharmaceutical drugs. As Reid explains: "You could have a completely new paradigm in managing infection. You may not even need antibiotics. You may not even need to kill the [infectious bacteria], you may just be able to stop the spread."
The implications for medicine are enormous at a time when bacteria are developing resistance to antibiotics at a staggering rate, largely due to the irresponsible overuse of these drugs. By using probiotics, doctors would be using evolutionary forces -- competition for survival in the body -- to defeat harmful bacteria.
"In a way, the century has come back round on its head again," laughs Reid.
Over 100 years ago, Metchnikoff showed that fermented milk could suppress the harmful activities of bacteria in the digestive tract. This was the research that won him the Nobel Prize. Another scientist, Arnold Cantani, treated tuberculosis by spraying Bacterium terumo into patients' lungs. The procedure proved surprisingly effective.
Ironically, it was the discovery of penicillin by Sir Alexander Fleming in 1929 that led to the demise of such promising fields of infection control as probiotics and bacteriophage -- viruses that eat bacteria. Within a few years, however, Fleming and other scientists reported that bacteria soon grow resistant to antibiotics.
Even more troubling, these germs can communicate this trait to one another, usually growing resistant to many different types of drugs at once. In Canada, the leading cause of hospital-acquired infection is multi-drug-resistant Staphylococcus aureus, the bug used in the London researchers' experiment.
Not only are antibiotic drugs becoming less effective, many consumers are growing weary of their effects, especially women coping with yeast infections that often follow a course of antibiotics.
"It's unbelievable," says Reid.
"They take an antibiotic to clear one infection, and then they get an anti-fungal to clear the yeast that was caused because of the antibiotic. And they're fed up with it."
Although North American consumers have heard little about probiotics, the market is on fire in Europe and Japan, where companies such as Danone SA, Nestle and Novartis are on the cutting edge of so-called functional foods. In Japan, where digestive health is a national obsession, millions of consumers drink Yakult brand probiotic drink. Introduced in Europe in 1996, sales of Yakult exceed 26 million bottles a day, or US$100-million a year.
Using germs to neutralize germs may sound strange to many people raised to consider all bacterial growth harmful. But scientists say it's more natural than potent chemicals that kill all the natural flora -- good and bad -- in our bodies. The human gut alone contains over a trillion species of bacteria, weighing about two kilograms, while billions more inhabit the throat, skin and other surfaces of our bodies.
"We have more bacteria in our body than we have cells," notes Reid. "We're basically a walking microbial culture."
In fact, there is some indication we each have a unique, personal set of protective bacteria, a kind of fingerprint that is formed by genetics and environmental factors such as whether a child is breast-fed or bottle-fed, delivered by Cesarean section or vaginally.
Scientists say the potential benefits of probiotics are extraordinary. Research suggests it may lower blood cholesterol, ease the torment of Crohn's disease, irritable bowel syndrome and other digestive disorders, as well as joint pain, flatulence and perhaps even colon cancer.
However, the field still suffers from a huge lack of credibility.
Few clinical trials have been conducted, so claims of medicinal benefits from probiotic yogourt and other foods have not been measured. Yet that hasn't stopped hundreds of companies from issuing over-hyped claims their product will cure everything from flatulence to cancer.
In Canada, many health food stores carry bacterial products such as acidophilus for treating yeast or fungal infections. These sometimes work, but not always. The reason is that not all strains of a particular bacterium are identical.
As Reid puts it, "Just because I'm the same height and weight as Donovan Bailey doesn't mean I can run as fast as he can. We need to do more work to determine the exact strains that are effective."
The London researchers have already made great strides in this area. Reid has treated women for urinary tract infections, bacterial vaginitis and other maladies with good success, and he predicts many infections will be treatable with over-the-counter, probiotic cheeses, yogourt and other foods within a few years.
"If you put in organisms that specifically have properties that will fight off infection or boost your immune response, then why not buy that cheese?" he says.
