A new strain of MRSA has been isolated from Helsinki hedgehogs, which has a high potential for spread in the community
NewsDesk @ bactiman63
For the first time, the highly contagious antibiotic-resistant strain of bacteria MRSA, which currently afflicts hospitals in Northern Europe, has been isolated from Helsinki’s hedgehogs. A study by Venla Johansson and colleagues at the University of Helsinki will be presented this year European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) Lisbon, Portugal (23-26 April).
The researchers say the findings suggest the spread of antimicrobial-resistant (AMR) bacteria and genes to urban wildlife and should be closely monitored to limit the emergence of new antimicrobial resistance traits worldwide in the future.
Superbacteria such as methicillin-resistant Staphylococcus aureus (MRSA) are antibiotic-resistant bacteria with limited or no treatment. European hedgehogs (Erinaceus europaeus) are common wildlife species in urban areas and were recently identified as a natural reservoir for MRSA. Studies in Denmark and Sweden also suggest that up to 60% of hedgehogs carry the MRSA type, the so-called mecC-MRSA, which causes one in 200 MRSA infections in humans.
Escherichia coli (E. coli) and Klebsiella pneumoniae Bacteria are common in the intestines of healthy people and animals. Highly resistant strains with broad-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) usually cause urinary tract infections in humans. Previous studies have shown that ESBL-E is common in European wild hedgehog populations. However, little is known about Finnish hedgehogs as stores of AMR bacteria or genes.
In order to find out the presence of these resistant bacteria in European hedgehogs in Finland, researchers tested samples of 115 dead hedgehogs from the Korkeasaari Zoo Wildlife Hospital in Helsinki in 2020–2021.
To test for the presence of MRSA, cotton swabs were taken from each hedgehog through the nose, mouth, and perineum, and stool samples were also collected to test for ESBL-E. Sequencing of the entire genome was then performed to examine the genomic properties of the bacteria, including virulence and resistant genes.
The study team found that about 1 in 10 (10%; 11/115) hedgehogs had colonized at least one MRSA-producing bacterial strain and at least one ESBL-producing strain (9%; 10/115).
Interestingly, four hedgehogs carried mecA-MRSA and belonged to a successful clone (t304 / ST6) that has appeared in human patients in northern Europe over the past few years. In Finland, most clinical MRSA infections are caused by mecA-MRSA.
However, only three hedgehogs carried the MRSA type named mecC-MRSA, previously reported to be common in European hedgehogs in Sweden and Denmark. This suggests that there appears to be genetic diversity and variability between hedgehog populations and countries between MRSA strains, the researchers say.
The study also found that the most common ESBL resistance genes were blaCTX-M-1 and blaCTX-M-15, which are common in human and animal isolates. The worldwide proliferation of BlaNDM-1 and other antibiotic-resistant genes is a growing concern, as they often target classes of “last resort” antibiotics, including carbapenem.
In addition, two E. coli the strains identified from the hedgehogs were of the human type (ST68 and ST69 – a common cause of severe bladder and circulatory infections in humans), suggesting that they may have been transmitted from humans to hedgehogs.
“This is the first report of a successful t304 / ST6 clone (with the potential to spread globally) in urban hedgehogs and highlights the need for further monitoring of potential sources of t304 / ST6 and its spread in urban environments,” says Johansson. “However, the clinical significance of the zoonotic potential or whether mecA-MRSA in hedgehogs is of clinical concern to the animals themselves is unknown.”
He continues: “It is amazing that we also found that about 10% of hedgehogs were positive for ESBL-E-producing bacteria – twice the incidence in humans and companion animals in Finland (5%). Our findings may indicate the spread of antimicrobial resistance from anthropogenic sources to urban wildlife and potentially create secondary stocks in an environment from which clinically significant resistance may spread elsewhere. “
However, Johansson points out that antibiotic-resistant bacteria are not just found in hedgehogs. “All wildlife and domestic animals carry a wide variety of bacteria, so there are many candidates for its spread to the urban environment, including humans themselves. In addition, anthropogenic sources such as waste, agricultural runoff, and domestic wastewater have been linked to the transmission of antimicrobial resistance to wildlife.
This observational study cannot prove that anthropogenic sources cause colonization of AMR bacteria in Finnish hedgehogs, but only suggests the possibility of such an effect. The authors refer to several limitations, such as the fact that they sampled hedgehogs in only one Finnish city, and the findings do not necessarily represent the entire country.
“In the future, hedgehogs transported by MRSA should be monitored in different environments and in a broader geographical context to determine if the hedgehogs could act as AMR guards to reveal AMR levels in the environment,” adds Johansson.