Antibiotic-resistant bacteria are a major global threat . According to the WHO (World Health Organization), one million people die each year from diseases caused by bacteria that do not respond to antibiotics. This can lead to a situation as daunting as that in the 21st century, a small wound that becomes infected could cost you your life . Now, a team of researchers has discovered that the rise of the superbug Staphylococcus aureus is not the result of misuse of antibiotics, but that it originated in hedgehogs in a very curious way.
What the researchers have found is that this resistant bacterium appeared as a result of an evolutionary struggle between fungi and bacteria on the skin of hedgehogs . The bacterium is present on the skin of hedgehogs and the parasitic fungus as well. The function of this is to secrete antibiotic to kill the bacteria. The bacteria, meanwhile, try to survive by developing resistance to the antibiotic. The bacteria subsequently passed to cattle and humans. The emergence of the superbug took place 200 years ago .
Although the use of antibiotics often drives the evolution of superbugs, this study recently published in Nature shows the origins of some antibiotic-resistant bacteria in nature. “We know that resistance genes were introduced into the genomes of pathogens before humans used antibiotics, but this really describes a mechanism for how this could happen,” study co-author Ewan Harrison, a researcher at the University , told Live Science. from Cambridge and the Wellcome Sanger Institute in the UK.
MRSA ( methicillin- resistant Staphylococcus aureus) is a strain of staphylococcal bacteria that is resistant to antibiotics and therefore more difficult to treat if it enters the body of humans or livestock and causes disease. The researchers investigated mecC-MRSA, a relatively rare form of the superbug that is responsible for about 1 in 200 human MRSA infections, according to a statement from the University of Cambridge.
mecC-MRSA was discovered in 2011 and was believed to have arisen in cows given large amounts of antibiotics. However, previous research has also found that up to 60% of European hedgehogs carry it . The hedgehog fungus, Trichophyton erinacei , creates its own penicillin antibiotics naturally to fight bacteria.
The researchers believe that this type of MRSA probably first evolved in hedgehogs, although they are not sure how mecC-MRSA passed on to humans. “We know that these resistance genes exist in the soil and in soil bacteria, and animals like hedgehogs and other wildlife obviously have a lot more contact with the soil on a day-to-day basis than most of us,” Harrison said.
Scientists point out that the superbug could have jumped to humans by having direct contact with hedgehogs . However, they believe that hedgehogs are not a risk and that we should not fear them . mecC-MRSA is also found in cattle, so these animals, or another unidentified animal, may have acted as intermediaries. Other MRSA lineages studied by the researchers originated around the time penicillin was introduced (1940s), suggesting that, in those cases, our use of antibiotics exerted selective pressure for resistance.
None of the hedgehog samples analyzed in Spain have tested positive for this superbug. In the countries where it has been found (UK, Denmark, Czech Republic, Portugal and New Zealand) it has been found for more than 200 years and mecC-MRSA infections from hedgehogs to humans are rare.
Ideally, do not disturb wildlife . In case of having contact with a wild hedgehog that, we insist, should not be had, the only thing we should do afterwards is wash our hands.
Fuente: Larsen, J., Raisen, C.L., Ba, X. et al. Emergence of methicillin resistance predates the clinical use of antibiotics. Nature (2022). https://doi.org/10.1038/s41586-021-04265-w
