A new study published today suggests that “it wasn’t the use of penicillin that drove the initial emergence of MRSA, it was a natural biological process[…] evolved in a battle for survival on the skin of hedgehogs, and […] spread to livestock and humans through direct contact.”

Antibiotic use in humans and animals, which has traditionally been blamed for the emergence of the antibiotic-resistant superbug MRSA, appears to have occurred in nature prior to the use of antibiotics in humans and livestock, according to scientists.

It was around 200 years ago that Staphylococcus aureus first developed resistance to the antibiotic methicillin, according to a large international collaboration that included researchers from the University of Cambridge, the Wellcome Sanger Institute, Denmark’s Serum Statens Institut, and the Royal Botanic Gardens, Kew, who traced the genetic history of the bacteria over a period of several years.

Hedgehog investigations from Denmark and Sweden revealed that up to 60 percent of hedgehogs carry mecC-MRSA, a variant of MRSA that is resistant to antibiotics. According to the findings of the new study, substantial levels of MRSA were identified in swabs taken from hedgehogs across their range in Europe and New Zealand.

Antibiotic resistance in Staphylococcus aureus originated as a result of having to coexist on the skin of hedgehogs with the fungus Trichophyton erinacei, which produces its own antibiotics, according to the researchers.

The resulting methicillin-resistant Staphylococcus aureus is commonly known as the superbug MRSA. The finding of this centuries-old antibiotic resistance occurred long before the widespread use of antibiotics in medical and agricultural settings.

“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 nineteenth century,” says Dr Ewan Harrison, senior author of the study.

“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.”

Antibiotic resistance in bacteria that cause human diseases was initially believed to be a recent phenomenon caused by the widespread use of antibiotics in clinical settings.

In the last few years, people have been taking too many antibiotics. Antibiotic resistance is now at dangerously high levels all over the world.

Considering that practically all of the antibiotics we use today originated in nature, the researchers believe it is likely that resistance to them already exists in nature as well. It is just a matter of time before overuse of any antibiotic in humans or cattle results in the development of resistant strains of the bug, and it is only a matter of time before that antibiotic begins to lose its effectiveness.

“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,” adds Professor Mark, another senior author of the report.

Previous research, conducted by Professor Holmes, was the first to identify mecC-MRSA in human and dairy cow populations in the year 2011. According to the current thinking, the strain developed in the cows as a result of the high doses of antibiotics that are frequently administered to them.

MRSA was discovered in patients for the first time in 1960, and mecC-MRSA is responsible for around one in every 200 MRSA infections. MRSA is significantly more difficult to treat than other bacterial infections because of its drug resistance. MRSA is now considered by the World Health Organization to be one of the world’s most serious risks to human health. It is also a significant challenge in the animal agricultural industry.

According to the researchers, the findings are not a reason to be afraid of hedgehogs because humans seldom contract mecC-MRSA infections, despite the fact that the bacteria has been present in hedgehogs for over 200 years.

”It isn’t just hedgehogs that harbour antibiotic-resistant bacteria – all wildlife carries many different types of bacteria, as well as parasites, fungi and viruses,” says Holmes.

“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.”

Source: 10.1038/s41586-021-04265-w

Image Credit: Getty

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