Forgotten Antibiotic From Decades Ago Could Be a Superbug Killer

An antibiotic that was created almost 80 years ago but left forgotten might once more provide innovative new answers, this time to the growing menace of drug-resistant superbugs.

In this so-called "golden age" of antibiotic discovery, over a century ago, we discovered many of the chemicals that make up half of the antibacterial medications we use today. One, known as streptothricin, was discovered in the 1940s and gained notoriety for its ability to cure illnesses brought on by so-called gram-negative bacteria.

These germs don't have the tough cell walls that many drugs target in gram-positive bacteria. One of the biggest problems facing the pharmaceutical sector has been the search for substitutes. The World Health Organization (WHO) published a list of the world's worst infections in 2017. Most of the microorganisms were gram-negative.

Streptothricin was not chosen, despite its capacity to destroy microorganisms. In an early investigation, it was determined to be too hazardous to human kidney health, and as a result, it was later forgotten in the scientific literature.

Now that it has been rediscovered, Harvard University pathologist James Kirby and his colleagues are investigating its potential as nourseothricin.

It is time to examine and consider the possibilities of what we previously disregarded, Kirby said in a statement to ScienceAlert. "Now with the emergence of multi-drug resistant pathogens, for which there are few if any active antibiotics available for treatment,"

A naturally occurring substance called nourseothricin is produced by gram-positive soil bacteria. In reality, it is a blend of antibiotics with names like streptothricin F (S-F) and streptothricin D (S-D).

In the laboratory, nourseothricin and S-D have been shown to have harmful effects on kidney cells, but Kirby and his colleagues have recently demonstrated that S-F doesn't have such effects. Even at hazardous quantities, this substance is still quite efficient in eliminating drug-resistant gram-negative bacteria.

S-F actually succeeded in eliminating a strain of bacteria in mouse models that has proven resistant to a number of common medications, all with little to no harm.

"Through centuries of evolution, soil-dwelling bacteria have learned how to create antibiotics that can pierce the defenses of gram-negative bacteria in their drive to protect their territory. One outcome of this continuous arms competition is streptothricins, according to Kirby.

These substances provide a special way to break through gram-negative bacteria' defensive systems.

Although the specifics of streptothricin's attack are still unclear, it appears that the antibiotic adheres to gram-negative bacteria differently than other medications and interferes with their ability to make proteins.

Researchers may be able to create a whole new class of antibiotics for germs that have so far shown to be extremely resistant if they can find out how.

Kirby and his colleagues have already begun looking into ways to improve natural streptothricins like S-F so they can combat superbugs even more effectively.

According to him, they "look forward to a resurgence of interest in this historically significant, yet long-forgotten class of antibiotics."

The study was published in PLOS Biology.