Scientists have discovered a powerful new antibiotic in soil bacteria that produce an already known drug. The new compound is 100 times more potent than the original and has the potential to destroy superbugs that are resistant to current antibiotics, according to a study published in the Journal of the American Chemical Society.
One of the greatest threats to humanity remains the rise of antibiotic resistance in bacteria. Scientists predict that by 2050, superbugs could directly or indirectly claim more than 39 million lives worldwide.
A new compound with antimicrobial properties, “hidden in plain sight”, was discovered during a study of the multi-step process by which the soil bacterium Streptomyces coelicolor produces the antibiotic methylenemycin A. This drug was first identified in 1965.
By 2010, scientists had described the mechanism of synthesis of methylenemycin A and identified several intermediates that occur in the process of its formation. Co-author Gregory Challis noted that at the time, the team “didn’t know what to do with the compounds they discovered, so they left the intermediates for a while.”
A few years later, a graduate student in Challis’s lab tested these molecules for antimicrobial activity and found that one of them, premethylenomycin C lactone, was 100 times more potent than the final product.
“The bacteria that produce methylenomycin A are one of the most studied antibiotic-producing species. Finding a new drug in such a familiar organism was a real surprise,” explained Lona Alkhalaf, a doctor at the University of Warwick in the UK.
The studies showed that even minimal doses of the new antibiotic can kill strains of bacteria that cause severe infections. These include Staphylococcus aureus, which infects the skin, blood and internal organs, and Enterococcus faecium, which can cause fatal infections of the blood and urinary tract.
Just 1 microgram of the new antibiotic per milliliter was enough to kill drug-resistant strains of Staphylococcus aureus, while 256 micrograms were needed to achieve the same effect for methylenemycin A.
The discovery could be a step towards creating new methods of fighting superbugs. However, before starting large-scale production, the researchers plan to establish the exact mechanism of action of the substance.
“We still don’t know what it affects. We think it could be an effect on the cell wall, ” said co-author of the work, chemical biologist Lon Alkhalaf.
In addition, scientists need to check whether the new molecules are toxic to mammalian cells to ensure that they are safe for humans.
