In a finding that will have broad implications for drug design, scientists have learnt how golden staph changes its shape to thwart last-line antibiotics.
Scientists based at Monash University's Biomedicine Discovery Institute used a giant microscope to document at a molecular level the changes that occurred in the bacteria when they became resistant to antibiotics.
The study, published in the journal mBio, found a "surprising, unorthodox method of resistance".
Nearly 1500 patients contracted golden staph in Australian public hospitals in 2014-15 and one in five cases were resistant to antibiotics, according to the latest government statistics.
The infection is also common in the community; most cases are harmless, but they can be deadly to people with sepsis.
Scientist and lead author Matthew Belousoff said almost all golden staph infections had become resistant to the most commonly prescribed antibiotic, methicillin, and drugs previously reserved as a last line of defence would soon need to be used in the first instance.
But over the past five years, some infections had become resistant even to these last-line drugs and scientists did not know how it had happened.
"What we know is that bacteria are wonderful at adapting to what are called environmental stresses - and nothing stresses out a life form more than something else trying to kill it," Dr Belousoff said.
"Obviously, we're trying to kill it with antibiotics and they adapt rapidly to that. But we don't know how they do it - the mechanisms, the cogs in the wheel."
Antibiotics attack infections by meddling with the bacterial ribosome, which is the part of the cell that makes proteins. If a cell cannot make protein, it dies.
"The way the antibiotic works is it throws a spanner in the works. The drug comes in and jams up the machine so the cell can't make protein any more."
Antibiotic-resistant bacteria find a way to apply oil and restart the machine.
Dr Belousoff's team compared the cell structure of resistant and non-resistant strains of golden staph under an electron microscope to learn that the latter infections had developed a mutation several cells away from the ribosome.
This mutation had a cascading effect on the structural arrangement of the cell to ultimately corrupt the antibiotic binding site.
The findings relate only to the way that golden staph has found a way to defeat the drug linezolid, but the technology developed by the team can now be adapted to design new drugs and examine other bacteria.
They will put scientists ahead in the constant battle against superbugs, but only for a time.
"The whole antibiotics game is like the Cold War. We keep making bigger weapons while the other side keeps making bigger weapons. There's essentially no such thing as a super-antibiotic."
