Gene sequencing shows common bug developed super powers a decade ago
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Gene sequencing shows common bug developed super powers a decade ago

A superbug that can cause almost untreatable infections has been spreading undetected through some of Victoria’s hospitals for almost a decade, researchers have discovered.

In one case, a patient booked in for routine surgery at the Austin Hospital ended up with an infection in his brain.

Staphylococcus on an agar plate.

Staphylococcus on an agar plate.Credit:Dr Jean Lee, Doherty Institute

The researchers say more needs to be done to track and kill the bug. Most hospitals don’t screen for it, while many labs dismiss findings as false positives.

“This bug, which we thought was pretty harmless and easy to treat, it has now developed several drug resistances – to the point where some strains are now near-untreatable,” says Dr Jean Lee, who led the team that made the finding.

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“A lot of hospitals and doctors don’t recognise this is a problem.”

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In 2012, Dr Lee was working as a clinician at the Austin when she came across a patient who wasn’t recovering.

The patient had been booked in for a routine operation, but during surgery contracted a Staphylococcus epidermidis infection in their brain.

This was no big deal – S. epidermidis (a relative of the much-more-dangerous superbug MRSA) is a normal dweller on human skin, and infections are extremely common and usually easily treated.

But the staph would not die. The team finally had to use last-line antibiotics to kill it, making treatment extremely difficult.

Shocked by watching a common infection shrug off powerful drugs, Dr Lee and her colleague Professor Benjamin Howden decided to sequence the bug’s genes. They discovered it had become resistant to the two main antibiotics used to treat it.

That would have been an interesting finding. What they did next catapulted their work into top journal Nature Microbiology.

Dr Jean Lee and Professor Ben Howden of The Peter Doherty Institute for Infection and Immunity.

Dr Jean Lee and Professor Ben Howden of The Peter Doherty Institute for Infection and Immunity.Credit:Simon Schluter

Working at the Doherty Institute in Melbourne, the pair first pulled up a database of staph swabbed at the Austin Hospital for the last decade.

Remarkably, they found their superbug-version of staph showing up as early as 2007.

Then they tested databases from other hospitals. And they discovered it was everywhere – in several hospitals across Melbourne, as well as hospitals in nine other countries in Europe and America.

Their bug had been spreading through hospitals around the world for at least 15 years and no one had noticed.

Staphylococcus colonies (in yellow).

Staphylococcus colonies (in yellow).Credit:Dr Jean Lee, Doherty Institute

Some strains overseas, the team found, had even developed resistance to all known antibiotics.

“It has been here this whole time and we never realised it,” says Dr Lee. “Nobody twigged that it had evolved to this point.”

Why? Because S. epidermidis is on everyone’s skin, when doctors test for infection they tend to ignore results indicating the bug's presence – assuming it got there by accident.

That means they could be overlooking the real culprit, says Dr Lee.

The state’s hospitals say patients shouldn't be worried. The Austin says it has two new reserve antibiotics that are still effective against the bug.

Monash hospital, which has recorded 10 "clinically significant" S. epidermidis infections, says its current infection control measures are up to the job.

“This won’t change our practice at all,” said Monash Health's head of infection prevention Associate Professor Rhonda Stuart.