Scientists have discovered a new antibiotic, teixobactin, that can kill serious infections in mice without encountering any detectable resistance, offering a potential new way to get ahead of dangerous evolving superbugs.
The new antibiotic was discovered in a sample of soil.
The research is “ingenious,” Dr. William Schaffner, an infectious disease specialist at Vanderbilt University, told The New York Times.
Researchers said the antibiotic, which has yet to be tested in humans, could one day be used to treat drug-resistant infections caused by the superbug MSRA, as well as tuberculosis, which normally requires a combination of drugs that can have adverse side effects.
Antibiotic-resistant infections already kill 700,000 people each year, with those numbers expected to rise.
“The discovery of this novel compound challenges long-held scientific beliefs and holds great promise for treating an array of menacing infections,” said Kim Lewis, a professor at Northeastern University and co-founder of the NovoBiotic Pharmaceuticals, which has patented teixobactin.
Still, experts urged caution. Though the researchers said they didn’t see signs of poisoning in the mice treated with teixobactin, antibiotics that show promise in mice are often toxic to humans.
“It’s at the test-tube and the mouse level, and mice are not men or women,” Schaffner told The Times. “Moving beyond that is a large step, and many compounds have failed.”
A New Kind Of Antibiotic
Lewis worked with researchers at Germany’s University of Bonn and with Britain’s Selcia Limited, and the finding was published in the journal Nature on Wednesday.
His co-researcher, Bonn’s Tanya Schneider, explained in a teleconference that teixobactin belongs to a new class of compounds and kills bacteria by causing their cell walls to break down. It seems to work by binding to multiple targets, she said, which may slow down the development of resistance. (Lewis estimated that it would take target bacteria 30 years or more to develop resistance to teixobactin, though that timeframe likely depends on how widely the drug is prescribed if it ends up on the market.)
The problem of infections developing drug resistance — a feature of medicine since Alexander Fleming’s discovery of the first antibiotic, penicillin, in 1928 — has worsened in recent years as multi-drug-resistant bugs have developed and drug companies have cut investment.
The World Health Organisation warned last year that a post-antibiotic era, where even basic healthcare becomes dangerous due to risk of infection during routine operations, could come this century unless something drastic is done.
More Where This Came From?
Lewis and his NovoBiotic colleagues sought to address the problem by tapping into new potential sources of antibiotics.
“The new research is based on the premise that everything on earth — plants, soil, people, animals — is teeming with microbes that compete fiercely to survive,” Denise Grady explained in The Times. “Trying to keep one another in check, the microbes secrete biological weapons: antibiotics.”
The team behind the new discovery developed a way of growing such microbes in their natural environment using a miniature device called an iChip that can isolate and help grow single cells.
Researchers have had trouble growing most bacteria outside of their natural environment, which makes it hard to study potential new antibiotics. The iChip, which bring the natural environment into the lab, may end up being a more important innovation than teixobactin itself.
“The method has the potential to be truly transformative, giving us access to a much greater diversity of environmental bacteria than previously imagined,” Gautam Dantas, a Washington University scientist who specialises in antibiotic resistance, told science writer Ed Yong.
The development of the iChip method means that Lewis and his team are well-positioned to discover even more good candidates for future antibiotics. “Teixobactin is a fish; the iChip is the rod,” Yong explained. “Having the rod guarantees that we’ll get more fish — and we desperately need more.”
NovoBiotic has so far collected about 50,000 strains of uncultured bacteria and discovered 25 new antibiotics, of which teixobactin is the latest and most interesting, Lewis said. “The rule of thumb in antibiotic discovery is if you have 50 good leads, from those you will get one drug,” Lewis explained. “That’s just the reality.”
One recent discovery, for example, proved to be too toxic to be used as an antibiotic, and is now being tested as a potential anticancer agent.
Proceed With Caution
Scientists not involved in the work welcomed the finding, but cautioned that human trials of teixobactin would be key.
“The discovery of a potential new class of antibiotics is good news,” said Richard Seabrook of Britain’s Wellcome Trust medical charity. “Screening previously unculturable soil bacteria is a new twist in the search … and it is encouraging to see this approach yielding results. However, we will not know whether teixobactin will be effective in humans until this research is taken … to clinical trials.”
Lewis hopes to begin those trials in about two years, and noted that even though the research has not been especially costly so far, they will need significant funding to bring the drug to market.
Even if all goes perfectly — and researchers could still discover problems that halt development — teixobactin won’t be available in hospitals for at least five years. It will be more expensive than generic antibiotics, and would likely take the form of an injection, not a pill. (Reuters by Kate Kelland; Editing by Ruth Pitchford)