“It essentially disarms the MRSA bacteria, preventing it from excreting the toxins it uses as weapons to damage tissues,” said Cassandra Quave, assistant professor of Biology at Emory University in Georgia.

“The body’s normal immune system then stands a better chance of healing a wound.”

Published in the journal Scientific Reports, the new study describes how the peppertree compounds were used to successfully treat the skin lesions of MRSA-infected mice, without damaging the tissue.

The Brazilian peppertree is native to South America, but is also abundant in much of Florida and is becoming more common in parts of neighbouring Alabama and Georgia, as well as in Texas and California.

Professor Quave said it was not surprising that, as a weed, the peppertree had a powerful chemical make-up.

“Persistent, weedy plants tend to have a chemical advantage in their ecosystems, which may help protect them from diseases so they can more easily spread in a new environment,” she said.

Last November Jeremy Hunt said NHS hospitals would be paid more for cutting infection rates and ordered them to publish figures reflecting how often staff wash their hands as part of a new drive against superbugs such as MRSA and E. coli.