Scientists pick noses to find new antibiotic

Bacterium located in human nostril may offer treatment for superbug strain MRSA

Scientists hunting for new antibiotics have scooped them from soil. They have searched in oceans and caves. And now, they are picking them out of your nose.

In a new paper published Wednesday in the journal Nature, German researchers report the discovery of a new antibiotic produced by a bacterium that lives inside the human nostril.

Experts say the paper is fascinating not just for the discovery of a potential new antibiotic — one that can kill a superbug called MRSA — but because it opens a potential new frontier in the desperate search for novel antibiotics: ourselves.

“Finding a new antibiotic is relatively rare. In the human microbiome, it’s super rare,” said Gerry Wright, an antibiotic resistance expert with McMaster University, who was not involved with the study. The human “microbiome” refers to the trillions of microbes that live on our skin and in our guts.

“It’s yet another great example of looking where people have rarely looked before — and finding something cool.”

This paper is just the latest effort to stave off what public health officials are calling a “post-antibiotic era” — a time when bacteria are resistant to all available antibiotics and a scraped knee or run-of-the-mill infection can kill.

People are already dying from once-treatable infections, and deaths caused by superbugs “are expected to become more frequent causes of death than cancer in the coming decades,” according to the study.

This crisis has renewed efforts to find new antibiotics and scientists have become increasingly creative in their search, with a handful of promising new compounds recently unearthed.

A starting point for this latest study was the observation that the bacterium Staphylococcus aureus, a common cause of infection, can be found in the nostrils of roughly 30 per cent of people.

These people are not necessarily infected — just “colonized” — though this bug is an opportunistic patho- gen, causing pneumonia or serious infections in people who are sick or immunocompromised.

The researchers asked themselves: what’s going on in the noses of people who aren’t harbouring this pathogen? One difference, they found, is the presence of another bacterium called Staphylococcus lugdunensis, which produces an antibiotic they’ve named “lugdunin.”

Analyzing the nasal swabs of 187 hospital patients, the researchers found that 9 per cent had this protective bacterium — and out of this group, only 6 per cent were colonized with Staphylococcus aureus.

In patients who didn’t have the bug, however, 35 per cent were colonized with Staphylococcus aureus.

“We started the project just for basic understanding (but) it led us to some very unexpected and exciting findings,” said co-author Andreas Peschel, a bacteriologist with the University of Tubingen.

“It was totally unexpected to find a human-associated bacterium to produce an antibiotic. This is usually known from soil or environmental bacteria.”

That said, bacteria-killing compounds have been discovered in the human microbiome before. After all, this is an ecosystem where more than a thousand microbial species compete for space, deploying antibiotics to kill their rivals.

But Staphylococcus lugdunensis uses a complex machinery to produce its chemical weaponry — something more often seen in bacteria living in soil, where the vast majority of modern-day antibiotics have been found.

“(This machinery) gives bacteria access to building blocks that otherwise they can’t get access to,” Wright explained. “And these researchers have shown that you can actually find that in some members of the human microbiome.

“That’s kind of a cool thing to me. You want to know: How did that happen? Does it happen a lot? Is there other examples of this in various microbiomes, and not just human ones?”

Laboratory tests showed that lugdunin was effective at wiping out not just Staphylococcus aureus, but also a superbug strain called MRSA, which is estimated to be 64 per cent more likely to cause death than nonresistant staph infections.

The antibiotic also cured mice infected in lab experiments.