John Murphy, MDLinx | July 29, 2016
An unrecognized antibiotic that’s effective against multi-resistant pathogens has been right under our nose—or rather, in our nose—all this time.
Most antibiotics have been isolated from bacteria in soil. Now, scientists have identified an antibiotic produced by a bacteria in the human nose that’s active against numerous pathogens, including Staphylococcus aureus and its resistant strains such as methacillin-resistant Staphylococcus aureus (MRSA), according to a study published July 29, 2016 in the journal Nature.
This discovery—that an antibiotic could be developed from human microbiota—suggests the possibility of overturning medicine’s losing battle against antibiotic resistance.
“Normally antibiotics are formed only by soil bacteria and fungi. The notion that human microflora may also be a source of antimicrobial agents is a new discovery,” said corresponding author Andreas Peschel, PhD, of the Interfaculty Institute for Microbiology and Infection Medicine in Tübingen, Germany.
Dr. Peschel predicted that the human microbiota will produce more than this one antibiotic. It could lead to many.
It’s well known that the natural habitat of harmful Staphylococcus bacteria is the human nasal cavity. But in this study, the researchers observed that Staphylococcus aureus is rarely found when another strain, Staphylococcus lugdunensis, is present in the nose. So they decided to do some digging.
The researchers took nasal swabs from 187 hospitalized patients and found that only about 6% of patients who carried S. lugdunensis also carried S. aureus. But in patients without S. lugdunensis, 34.7% had S. aureus. This suggested that S. lugdunensis somehow competes with the pernicious S. aureus, and also inhibits it.
From S. lugdunensis, the investigators developed the antibiotic they named lugdunin. To test it, the researchers infected the skin of mice with S. aureus; their lugdunin ointment killed the infection both on the surface and in deeper layers of the skin. In addition to MRSA, lugdunin killed S. aureus resistant to the antibiotic glycopeptide and vancomycin-resistant Enterococcus spp.
Further testing and study needs to be done, and lugdunin itself may not be the giant-killer of antibiotic resistance—but its discovery points to a new human-derived method of developing drugs to combat resistant infections.
“Considering that lugdunin can inhibit the synthesis of major biopolymers (proteins, DNA, and peptidoglycans) in S. aureus, it is probably a membrane-acting antibiotic, which would be challenging to develop into a systemic therapeutic because such compounds also tend to disrupt membranes of mammalian cells,” wrote Kim Lewis, PhD, and Philip Strandwitz, PhD, of the Antimicrobial Discovery Center at Northeastern University in Boston, MA, in an accompanying Nature editorial.
However, they added, the method of discovery of lugdunin “provides a general approach to investigating antibiotic-driven colonization resistance of the human microbiota against pathogens,” which ultimately has the potential to produce novel antibiotics.