Scientists have found evidence that a type of the antibiotic resistant superbug MRSA arose in nature long before the use of antibiotics in humans and livestock, which has traditionally been blamed for its emergence.
According to a large international collaboration including the University of Cambridge, the Wellcome Sanger Institute, Denmark’s Serum Statens Institut and the Royal Botanic Gardens, Kew, Staphylococcus aureus first developed resistance to the antibiotic methicillin around 200 years ago.
It was a natural biological process, and predates antibiotic use in medical and agricultural settings, they said.
Hedgehogs carry a fungus and a bacteria on their skin, and the two are locked in a battle for survival. The researchers said that antibiotic resistance evolved in Staphylococcus aureus as an adaptation to having to exist side-by-side on the skin of hedgehogs with the fungus Trichophyton erinacei, which produces its own antibiotics.
The fungus secretes antibiotics to kill the bacteria and in response, the bacteria has evolved antibiotic resistance becoming Methicillin-resistant Staphylococcus aureus, or MRSA.
In the study, published in the journal Nature, the team conducted hedgehog surveys from Denmark and Sweden and found that up to 60 per cent of hedgehogs carry a type of MRSA called mecC-MRSA.
The new study also found high levels of MRSA in swabs taken from hedgehogs across their range in Europe and New Zealand.
“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,” said Dr Ewan Harrison, a researcher at the Wellcome Institute and Cambridge University.
Antibiotic resistance in bugs causing human infections was previously thought to be a modern phenomenon, driven by the clinical use of antibiotics. Misuse of antibiotics is now accelerating the process, and antibiotic resistance is rising to dangerously high levels in all parts of the world.
“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,” said Professor Mark Holmes, a researcher at Cambridge’s Department of Veterinary Medicine.
MRSA was first identified in patients in 1960, and around 1 in 200 of all MRSA infections are caused by mecC-MRSA. Due to its resistance to antibiotics, MRSA is much harder to treat than other bacterial infections.
The World Health Organisation now considers MRSA one of the world’s greatest threats to human health. It is also a major challenge in livestock farming.