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Hedgehogs have been living with MRSA on their skin for the last two centuries, a new Cambridge study has found, suggesting humans did not cause antibiotic resistance.

Scientists have uncovered startling new evidence that the superbug arose in the natural world long before the use of drugs such as penicillin, which have traditionally been blamed for its emergence.

The new research has the potential to fundamentally change our understanding of where and how MRSA developed.

The study revealed hedgehogs carry a fungus and a bacteria on their skin which are locked in a “battle for survival”.

Antibiotics designed to kill the bacteria are secreted by the fungus. However, in response, the bacteria has evolved antibiotic resistance – becoming Methicillin-resistant Staphylococcus aureus, or MRSA.

Up to 60 per cent of hedgehogs carry a type of MRSA called mecC-MRSA, which causes one in 200 of all MRSA infections in humans, according to the study.

The researchers suggest natural biological processes, not antibiotic use, drove the initial emergence of this superbug among hedgehogs about 200 years ago.

The study was an international collaboration including the University of Cambridge, the Wellcome Sanger Institute, Denmark’s Serum Statens Institut and the Royal Botanic Gardens, Kew, which has traced the genetic history of the bacteria.

The scientists began investigating the discovery, which was first found in hedgehogs in Denmark and Sweden, and subsequently found high levels of MRSA in swabs taken from hedgehogs across Europe and New Zealand.

Dr Ewan Harrison, a researcher at the Wellcome Sanger Institute and University of Cambridge and a senior author of the study, said: “Using sequencing technology, we have traced the genes that give mecC-MRSA its antibiotic resistance all the way back to their first appearance, and found they were around in the 19th century.

“Our study suggests that it wasn’t the use of penicillin that drove the initial emergence of MRSA, it was a natural biological process.

“We think MRSA evolved in a battle for survival on the skin of hedgehogs, and subsequently spread to livestock and humans through direct contact.”

‘Stark warning’ over the use of antibiotics

Penicillin was not discovered until 1928, by Alexander Fleming at St Mary’s Hospital, in London.

Given that almost all the antibiotics used today arose in nature, the researchers say it is likely resistance to them already exists in nature too.

Overuse of any antibiotic in humans or livestock will favour resistant strains of the bug, so it is only a matter of time before the antibiotic starts to lose its effectiveness.

The World Health Organization has warned that MRSA and other superbugs could return medicine to the “Dark Ages” if not used responsibly.

Professor Mark Holmes, a researcher in the University of Cambridge’s department of veterinary medicine and a senior author of the report, said: “This study is a stark warning that when we use antibiotics, we have to use them with care.

“There’s a very big wildlife reservoir where antibiotic-resistant bacteria can survive and, from there, it’s a short step for them to be picked up by livestock and, then, to infect humans.”

No reason to fear hedgehogs

Previous work led by Prof Holmes first identified mecC-MRSA in human and dairy cow populations.

At that time, it was assumed the strain had arisen in the cows because of the large amount of antibiotics they are routinely given.

However, the researchers say the new findings are not a reason to fear your local hedgehogs, as humans very rarely get infections with mecC-MRSA

Prof Holmes said: “Wild animals, livestock and humans are all interconnected – we all share one ecosystem.

“It isn’t possible to understand the evolution of antibiotic resistance unless you look at the whole system.”

The research, published in Nature, was funded by the Medical Research Council.

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