One potential answer to the growing problem of antibiotic resistant infections may have been right under our noses all along—or rather, in them.
Today (July 27), researchers from the University of Tübingen in Germany identified a nose-dwelling bacteria capable of producing a compound that can kill methicillin-resistant Staphylococcus aureus, better known as the superbug MRSA. Their work was published (paywall) in Nature.
“We are happy that we discovered this new compound, because it is a new class of antimicrobial—not just a new molecule,” Andreas Peschel, a bacteriologist at the University of Tübingen and lead author of the paper, said in a press conference.
Antibiotics, often derived from chemicals found naturally in existing microbes in soil or the natural environment, revolutionized the way we treat bacterial infections like pneumonia, tuberculosis, and gonorrhea. Over the years, some bacteria have evolved to withstand these treatments. This can happen when antibiotics kill off most, but not all, of the bacteria responsible for an infection, and those remaining flourish. Alternatively, bacteria can become resistant with a kind of asexual gene-swapping called horizontal gene transfer. Some bacteria can take up bits of free-floating genetic material, or can trade with some surrounding bacteria—either within or outside of their own species.
Antibiotic-resistant bacterial infections, including those caused by MSRA, can be overcome if patient’s own immune system is capable of fighting the infection on its own, but this isn’t always possible. And when no alternative treatments are available, they can be fatal: The US Centers for Disease Control estimates that 23,000 people die of these types of infections each year.
MRSA infections have become a growing problem; from 2003 to 2008, the number of cases reported (paywall) in hospitals grew from about 21 cases per 1,000 visits to 42 per 1,000. To fight back, researchers are looking for new sources of compounds to develop drugs, including our own bodies. We have a huge collection of bacteria collectively called our microbiota (or microbiome, referring to all the genes these bacteria have) living everywhere from inside our digestive tract to on our skin and in our nasal passages. Most of these bacteria are benign or even beneficial to us.
One of these benign bacteria, called Staphylococcus lugdunensis, lives in our nose and produces a chemical called lugdunin that researchers believe might have antibiotic properties. Peschel and his team swabbed the inside of almost 200 individual’s noses and found that only about 6% of people who carried S. lugdunesis also carried S. aureus, whereas the latter showed up in about 30% of patients without a colony of S. lugdunesis.
To test whether that correlation meant that lugdunin could be used as an antibiotics, the researchers then took 10 mice and gave them two MRSA skin infections each. They treated half of the 20 infections sites with with doses of concentrated lugdunin and others with nothing. In most cases, the infections treated with lugdunin cleared up within three days. (Peschel said that the two mice who had small amounts of MRSA left in their skin likely licked the ointment off.)
The researchers hope that lugdunin will be a powerful new antibiotic that can be used preventatively for patients with compromised immune systems who may be at risk of developing MSRA infections. It will still be years before the drug is available for patients, but Peschel thinks that its discovery opens the doors for the discovery of hundreds of other compounds from within the human microbiota. “The human body has a lot of different ecological niches that can be tested,” he said.