New research finds the bacteria that make up the human microbiome might be an untapped resource of potential antibiotics.
By Kate Wheeling
(Photo: Bradley Gordon/Flickr)
There are communities of bacteria roughly 50 species strong living in every human nose. The make-up of these nasal ecosystems varies from person to person, but at least one known strain produces an antibiotic capable of killing the nefarious bacterium called Staphylococcus aureus, including even varieties that are resistant to standard antibiotics, researchers report today in Nature.
Humans began losing the evolutionary arms race against bacteria almost as soon as we discovered and started mass producing antibiotics. The organisms simply developed and traded mutations that allowed them to survive assaults from anti-bacterial drugs. Antibiotic-resistant bacteria are a growing cause of death worldwide, and could surpass cancer as a cause of death in as few as 10 years, according to lead author Andreas Peschel, a bacteriologist at the University of Tübingen in Germany.
The compound Peschel and his colleagues discovered represents a new class of antibiotic: Most known antibiotics are produced by bacteria in the soil or elsewhere in the environment, so the team was surprised to find an antibiotic produced by a microbe found within the human body, Peschel said in a press conference.
Our own microbiomes may be an untapped reserve of antibiotic sources.
The authors discovered the new antibiotic by looking at other Staphylococcus strains to find out if any had the capacity to outcompete or kill S. aureus. They found that S. lugdunensis produced an anti-bacterial substance that prevented the growth of S. aureus. They named the new antibiotic lugdunin.
The researchers found that, even in small concentrations, lugdunin was effective against many different kinds of antibiotic-resistant bacteria, including the increasingly common hospital-acquired infection called methicillin-resistant S. aureus, or MRSA. When the authors treated S. aureus skin infections in mice with lugdunin, the antibiotic reduced the bacterial load or completely cleared the infection. And S. aureus did not develop a resistance to the new antibiotic, even when the authors exposed the bacterium to sub-lethal doses of lugdunin for 30 days — a time period equivalent to upwards of 1,000 generations on bacterial timescales and usually more than enough time for a resistance mutation to emerge.
Though clinical applications could still be years away, the researchers have reason to be optimistic that this new antibiotic, or others like it that have yet to be discovered, will benefit humans as well as mice. When the team took samples from the noses of 187 hospital patients, more than 30 percent tested positive for S. aureus, and roughly 9 percent for S. lugdunensis. Patients without the latter were almost six times more likely to have populations of S. aureus in their noses — a major disadvantage considering most invasive (and potentially harmful) infections stem from populations of drug-resistant bacteria living somewhere on the body.
“When there is a severe infection it is usually the same strain that the patient or his neighbor or his nurse has been carrying around,” Peschal explains.
Even if lugdunin never makes it to the clinic, the authors note that the most important takeaway from the new study is that our own microbiomes may be an untapped reserve of antibiotic sources.