Of all the 20th century’s innovations, the discovery of antibiotics was hands-down one of the most important. Since Alexander Fleming first discovered penicillin in 1928, countless lives have been saved from previously untreatable diseases and epidemics stopped in their tracks. Since the 1980s, however, researchers have struggled to find new treatments as an increasing number of diseases developed a resistance to antibiotics. Now, for the first time in 30 years, scientists have discovered a new class of antibiotic, and it was hiding right under their noses.

Scientists searching for new antibiotics have traditionally looked to bacteria that live in soil for the chemical compounds they use to fight off their rivals. But the human body has long been seen as a potential resource for antibiotic compounds, Alessandra Potenza reports for The Verge. It's packed with all manner of microbes—from skin to guts. And while scientists have learned much about the body in recent decades, there is still a lot unknown about the human microbiome.

Microbiologists from the University of Tübingen, Germany, turned to the nose, which is a perfect environment for bacteria to thrive. It provides direct access to the bloodstream for bacteria to sneak past the immune system, and a warm, humid environment for micobes to breed.

While many species of bacteria make their homes up our noses, the researchers looked at a particular one called Methicillin-Resistant Staphylococcus aureus (MRSA)—a species that can cause deadly infections in people with weakened immune systems and is found in 30 percent of people's noses, Kate Baggaley writes for Popular Science. But the researchers were curious what kept the other 70 percent from sporting the microbes.

They swabbed subjects' noses and looked at what was living up there, identifying another bacterium called Staphylococcus lugdunensis that produces a chemical compound that can fight MRSA and many other species of bacteria, Potenza reports. Not only that, but the chemical called “lugdunin” belongs to a new class of antibiotics. "Lugdunin is just the first example," study co-author Andreas Peschel tells Potenza. "Maybe it’s just the tip of the iceberg."

"It may seem surprising that a member of the human microbiota—the community of bacteria that inhabits the body—produces an antibiotic,” Kim Lewis and Philip Strandwitz, microbial biologists at Northeastern University who were not involved with the study, tell the BBC. "However, the microbiota is composed of more than a thousand species, many of which compete for space and nutrients, and the selective pressure to eliminate bacterial neighbors is high."

While lugdunin shows promise, it’s likely to be a long time before it is used as a medical treatment. Even so, there’s still a ticking clock on the potential drug, as it’s likely microbes will evolve resistance to it just as they did to previous antibiotics, Potenza reports.

"That is a naturally produced substance by an organism that’s been competing in its niche for millions, if not billions, of years," Brad Spellberg, a professor of clinical medicine at the University of Southern California who was not involved in the study, tells Potenza. "Resistance will develop, it’s inevitable."

Whatever happens down the line with lugdunin, the study suggests that our own bodies may hide a wealth of possible antibiotics that could be used to fight off deadly diseases. With antibiotic-resistant bacteria projected to kill millions of people a year by 2050, this find could not have come at a better time.