Three new strains of a superbug have been discovered in Victorian hospitals, leaving the sickest patients at risk of life-threatening infections.

Researchers have found a multi-drug resistant bacterium in numerous hospitals in Victoria and around the world, with some strains in Europe resistant to all known antibiotics.

The research, published in Nature Microbiology on Tuesday, also showed Staphylococcus epidermidis can infect people who are immunocompromised or have had prosthetic materials implanted, such as catheters and joint replacements.

Lead author Dr Jean Lee says the bacteria, found on the skin of all humans, can enter the body on medical devices and form a coat that protects it from antibiotics and the immune system.

"If we're unable to get on top of the infection, because the bacteria isn't responding to the antibiotics then it's potentially life threatening," Dr Lee told AAP.

Dr Lee, from the Doherty Institute, said Staphylococcus epidermidis made a small change in its DNA that led to resistance to two major antibiotics.

"These two antibiotics are unrelated and you would not expect one mutation to cause both antibiotics to fail," she said.

The current guideline for treating infections uses a combination of these two major antibiotics because they have been thought to protect one another against developing resistance.

Dr Lee said the study showed this assumption was incorrect and the current treatment recommendations need to be reviewed.

At this stage, it is not known how many people have been infected by the superbug and whether there have been any deaths, she said.

Researchers looked at hundreds of Staphylococcus epidermidis isolates from 78 institutions in 10 countries around the world before they discovered the three strains resistant to nearly all antibiotics.

"In the next stage, we need to go back and measure and determine the impact and start to put in interventions," Dr Lee said.