Sniffing out a new antibiotic

Scientists have long sought novel antibiotics by searching for compounds made by bacteria living in soils from exotic locales or on the seafloor. It turns we don’t always have to go to such extremes. Researchers have now found a member of a whole new class of antibiotics hiding under our noses. The compound, called lugdunin, is a key weapon in the bacterial battle that’s raging within our nostrils.

Staphylococcus aureus colonizes the nasal passages of about 30% the human population. The bacterium bides its time there, looking for chances to spread and waiting for the opportunity to launch a serious infection within its human host. Researchers led by University of Tübingen microbiologists Andreas Peschel and Bernhard Krismer wondered what keeps S. aureus at bay in the other 70% of people. They went looking up our noses for answers.

Peschel and Krismer’s team discovered that another Staphylococcus bacterium, S. lugdunensis, produces a compound that kills S. aureus. The researchers identified and characterized the molecule, a novel thiazolidine-containing cyclic peptide they named lugdunin, which is the first antibiotic to come from a bacterium that lives primarily in people (Nature 2016, DOI: 10.1038/nature18634).

The team started this project simply to understand what was happening to bacteria in our nostrils, Peschel says. “But it led us to some very unexpected and exciting findings,” he says, adding that the discovery could lead to the development of new drugs for fighting strains of bacteria that have become resistant to our existing antibiotic arsenal. “It is a new class of antimicrobial,” he says, “not just another molecule.”

Lugdunin killed both methicillin-resistant S. aureus and vancomycin-resistant enterococci in cell culture tests. The compound also cleared up S. aureus skin infections in mice when applied topically.

Kim Lewis, a microbiologist at Northeastern University, says Peschel and Krismer’s work could spur scientists to start looking at bacterial fights in our bodies for new antimicrobial compounds.

Scientists have long known that S. aureus had a propensity to live in some people’s noses, Lewis says. “The breakthrough here is that from a set of mundane and well-known observations they explain why S. aureus colonizes only 30% of human noses and not 100%.”

Peschel and Krismer don’t yet know how lugdunin kills bacteria. They have patented the compound and are now looking to mine other human-associated bacteria for novel antibiotics.

This article has been translated into Chinese and can be found here.

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