Digging the dirt on AMR: Discovery of new antibiotics offer hope in superbug fight

Recent research from a team at Rockefeller University has uncovered natural compounds in soil samples that may be useful in the treatment of several bacterial infections that have become resistant to multiple antibiotics.

The researchers had hypothesized that there could be many new calcium-dependent antibiotics housed within soil microbiomes that have not been reported in previous culture-based natural product efforts. So, to test their hypothesis they analysed multiple soil samples from a variety of US-based locations using a discovery platform that involves sequencing.

More than 2,000 soil samples, taken from ecologically and geographically diverse environments, were analysed in the study using the sequencing platform. From this analysis, the team realised that there were many uncharacterised antibiotic families present in the soil samples, an abundant one, found in nearly a fifth of metagenomes, they named malacidin.

Once they had recovered the structure of the malacidins and isolated them from their samples, the researchers tested their antibacterial activity in rat models that were infected with methicillin-resistant Staphylococcus aureus (MRSA). In these experiments, it was found that the malacidins worked as calcium-dependent antibiotics against MRSA — a multidrug-resistant Gram-positive pathogen.

“It is impossible to say when, or even if, an early stage antibiotic discovery like the malacidins will proceed to the clinic,” explained Dr Sean Brady, team leader at the Rockefeller University, New York, when speaking to the BBC. “It is a long, arduous road from the initial discovery of an antibiotic to a clinically used entity.”

This research has been published online as an open-access letter in the journal Nature Microbiology.