By Megan Tseng
MRSA, or methicillin-resistant Staphylococcus aureus, may seem like a familiar name.
MRSA infections are most commonly seen in hospital patients and are notoriously difficult to treat. Superbugs like MRSA serve as a warning of the dangers of antibiotics and producing drug-resistant strains of bacteria. When we think of these infections, we typically imagine them to start with overused antibiotics.
Recent studies have shown that a particular type of MRSA, mecC-MRSA, may have originated from hedgehogs.
A photo of a European hedgehog.
In past years, scientists have observed high proportions of MRSA in European hedgehog populations. This trend, combined with hedgehogs’ tendency to interact with humans, was what prompted further research on the hedgehog’s evolutionary role in MRSA.
Scientists from Statens Serum Institut in Copenhagen, Denmark, began their research by investigating the distribution of MRSA in hedgehogs all over Europe. They collected samples of dead hedgehogs and swabbed their noses, skin, and feet for any bacteria. With the use of PCR, 61% of the collected hedgehogs were found to carry mecC-MRSA, a type of MRSA with a divergent mec gene. Unique genes in the hedgehogs’ mecC-MRSA confirm it to be the animal-adapted, and not human-adapted, version. After identifying different strains of the mecC-MRSA, researchers constructed detailed evolutionary relationships and found that 9 of the 16 strains could have possibly originated from hedgehogs almost 200 years ago, long before antibiotics were created.
In comparison with hedgehogs, other mammals such as deer harbor much less MRSA bacteria; how is it that hedgehogs were the ones to bring about the superbug? The answer may lie in fungi. Trichophyton erinacei, a fungi that lives on hedgehog skin, cohabitates with MRSA and competes for resources. After growing in the lab, the fungus was found to secrete two types of penicillin-like antibiotics. Scientists hypothesize that living in an environment with penicillin may have forced Staphylococcus aureus to adopt drug resistance through natural selection.
These findings indicate that hedgehogs act as a reservoir for MRSA and contributed to its origin. This highlights the environment’s connections to the formation of drug resistance even in the absence of human disturbance. Further investigation into the ways zoonosis could have occurred between hedgehogs and humans could help to prevent the spread of future superbugs like MRSA.
Sources:
Paterson, Gavin K et al. “The emergence of mecC methicillin-resistant Staphylococcus aureus.” Trends in microbiology vol. 22,1 (2014): 42-7. doi:10.1016/j.tim.2013.11.003.
“European Hedgehog.” World Land Trust, 2022. worldlandtrust.org/species/mammals/european-hedgehog/.