Researchers from WildCRU, Statens Serum Institut, Cambridge University, and Wellcome Sanger Institute and have shown that particular strains of methicillin-resistant Staphylococcus aureus (MRSA), some of the most infamous and dreaded disease-causing microorganisms in humans, were present in hedgehogs long before methicillin came on the market in 1959.
The discovery of antibiotics more than 80 years ago has led to significant improvements in human and animal health. But every time a new antibiotic was put into use, the bacteria quickly responded by becoming resistant. Until now, it has been assumed that resistance in disease-causing bacteria is a modern phenomenon driven by clinical use of antibiotics. However, it has been a big mystery how resistance could arise so quickly. Now a new study – co-authored by WildCRU's Sophie Lund Rasmussen - has solved part of the riddle.
Previous research showed that a kind of MRSA known as mecC-MRSA is widespread among hedgehogs in several western and central European countries, as well as in New Zealand, where hedgehogs were introduced from Great Britain in the 19th century. The bacteria are so-called because they carry a gene called mecC that makes them resistant to the antibiotic methicillin.
"The high occurrence of mecC-MRSA in hedgehogs is surprising, because they are wild animals that are not exposed to antibiotic treatment" - Anders Rhod Larsen, head of the Reference Laboratory for Antibiotic Resistance at Statens Serum Institut.
Since the kind of mecC-MRSA found on hedgehogs was first described in 2011, it has been thought that the bacteria came from cows, but this theory is now proving to be incorrect. The study shows that MRSA originated from hedgehogs, from whom they spread to domestic animals and humans.
The antibiotic resistance developed naturally in hedgehogs due to the presence of the hedgehog ringworm. Hedgehog ringworm produces natural antibiotics which came into contact with the Staphylococcus aureus naturally found in hedgehogs’ snouts. The bacteria developed resistance and became mecC-MRSA bacteria in the hedgehogs because they were exposed to the antibiotics of the ringworm.
According to Anders Rhod Larsen, the new findings give reason to change our view of antibiotic resistance:
“The development of resistance to clinically relevant antibiotics in natural environments with subsequent spread to domestic animals and humans underlines the close link between these reservoirs. This more holistic (One Health) view of antibiotic resistance is crucial to our understanding and management of resistant bacteria, which today pose one of the greatest threats to global health, food security and the economy.”
Should we be afraid of hedgehogs in our gardens?
The short answer is no. Humans rarely get infections with mecC-MRSA bacteria, even though they have been present in hedgehogs for more than 200 years. In addition, people enjoy having hedgehogs in their gardens, and our efforts to understand and protect the drastically declining population of hedgehogs, are vital.
"But it is important to keep in mind that wild animals can carry bacteria, parasites, fungi and viruses, which in rare cases can cause disease in humans. Therefore, it is important to always maintain good hand hygiene when feeding and possibly handling hedgehogs. Both for the sake of the hedgehogs and ourselves" - Dr Sophie Lund Rasmussen.
To read more about this research, published in Nature, please visit: https://www.nature.com/articles/s41586-021-04265-w