How the First New Antibiotic in 30 Years Was Grown in Dirt
The way it was discovered may be the most exciting part.
After decades of using the same old methods, researchers have developed the first new antibiotic in three decades. The results for the antibiotic are early because it hasn't yet been tested on humans, but it's the technique for developing the antibiotic that some in the field are calling a "paradigm shift" that could quell the looming threat of antibiotic resistance.
"I think it was a remarkable success and finding," said Stuart Levy, the director of the Center for Adaptation Genetics and Drug Resistance at Tufts University in Boston. "If this were easy and simple [to do], you would say 'I can set this up tomorrow in my lab.' But it's not."
The team of researchers, led by Kim Lewis of Northeastern University in Boston, Massachusetts, didn't start out by looking for antibiotics at all; they were testing how to grow bacteria in soil. The researchers created an electronic chip on which bacteria can grow. Most antibiotics come from bacteria and fungi found in soil, but over the years scientists have found it difficult to work with them in the lab.
"The majority of bacteria on this planet are 'uncultured,' meaning they don't grow on our petri dishes, and when I'm talking about 'the majority,' it is 99 percent," Lewis told NPR. To get these touchy bacteria to grow in a way they can use, the researchers isolate the bacteria in chambers in the chip, which is covered with two semi-permeable membranes. The researchers then return the chip to the soil so the bacteria can grow in their natural environment. When the bacterial culture is big enough, the researchers remove the chip, isolate the antibiotic molecules, and see how well they fight off infection.
As a result, the researchers were able to isolate dozens of molecules that had proven tricky in lab settings, according to the study published this week in Nature. But one in particular, which they named teixobactin, was very effective. When put into a petri dish, it killed off a large number of the germs that cause the intestinal infection C. diff, the disease-causing agent in anthrax, and the notorious staph. When they tested teixobactin in mice, the researchers found that it cured mice of thigh and lung infections.
Some promising antibiotics actually increased the number of patient deaths
Teixobactin is tantalizing, but experts warn that the study is still preliminary. "Animal studies and test tube tests are NOT predictive of efficacy and safety in humans," said one infectious disease researcher with experience in drug development (he did not want to be named because he has ties to the National Institutes of Health). Some promising antibiotics, such as doripenem and tigecycline, actually increased the number of patient deaths. And, although the researchers claim that teixobactin's uncommon mechanism means that it will be stronger against resistance, "it would take years of clinical use to know if resistance will or will not develop," the infectious disease researcher said.
Levy thinks it will take more than a few years to go on the market and, depending on how long it takes, it could even be prohibitively expensive. There's no way to tell yet.
Teixobactin may be met with cautious excitement, but the technique for discovering antibiotics is the biggest discovery to Levy and others in the field. Since penicillin first became available in the 1940s, more than 100 new antibiotics have come on the market. But in recent years the pace of development has slowed as pharmaceutical companies have set their sights on more profitable drugs. Meanwhile, disease-causing bacteria have evolved so that some older antibiotics don't work as well as they used to, which we call antibiotic resistance. Experts have called this an "apocalyptic threat," fearing unstoppable "superbugs," while others have tapped pharmaceutical companies and government agencies to streamline the production of new antibiotics.
The technique these researchers used could lead scientists to new antibiotics more quickly, which could be much more effective in fighting the diseases that have already become resistant.
"This is a novel, new way of looking for new antibiotics to treat resistance," Levy said. "It's the ability to grow something that doesn't grow in the lab."