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.
