Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is an important emerging zoonotic pathogen that causes severe skin infections. In new research, scientists have screened a collection of diverse Staphylococcus species from domestic dogs and cats for antimicrobial activity against MRSP. They’ve successfully isolated a unique strain — Staphylococcus felis C4 — from cat skin that inhibited MRSP and multiple Gram-positive pathogens.
To identify candidates for a new bacteriotherapy against skin infection, O’Neill et al. screened various bacteria from dogs and cats and co-cultured them with Staphylococcus felis C4 in liquid and agar antimicrobial assays. Image credit: O’Neill et al., doi: 10.7554/eLife.66793.
Skin is colonized by hundreds of diverse bacterial species that exist within a complex and dynamic chemical landscape.
These chemical interactions can play important roles in skin health, immune education and protection against pathogen colonization and infection.
The composition of the skin microbial community of humans and animals varies extensively, in part due to different skin habitats, i.e. increased hair density in animals, as well as more subtle differences in the chemical and biological conditions of the skin.
Overall, the human microbial skin community is distinct from and significantly less diverse than that of both wild and domestic animals.
“Our health absolutely depends on these ‘good’ bacteria,” said senior author Professor Richard Gallo, chair of the Department of Dermatology at the University of California, San Diego.
“They rely on our healthy skin to live, and in return some of them protect us from ‘bad’ bacteria.”
“But if we get sick, ‘bad’ bacteria can take advantage of our weakened defenses and cause infection.”
In the study, Professor Gallo and colleagues screened a library of bacteria that normally live on dogs and cats and grew them in the presence of MRSP.
From this, they identified a strain of cat bacteria — Staphylococcus felis C4 — that was especially good at inhibiting MRSP growth.
They found that this special strain naturally produces multiple antibiotics that kill MRSP by disrupting its cell wall and increasing the production of toxic free radicals.
“The potency of this species is extreme,” Professor Gallo said.
“It is strongly capable of killing pathogens, in part because it attacks them from many sides — a strategy known as ‘polypharmacy.’ This makes it particularly attractive as a therapeutic.”
Bacteria can easily develop resistance to a single antibiotic. To get around this, Staphylococcus felis C4 has four genes that code for four distinct antimicrobial peptides.
Each of these antibiotics is capable of killing MRSP on their own, but by working together, they make it more difficult for the bacteria to fight back.
Having established how Staphylococcus felis C4 kills the MRSP, the next step was to see whether it could work as a therapy on a live animal.
The researchers exposed mice to the most common form of the pathogen and then added either Staphylococcus felis C4 or bacterial extract to the same site.
The skin showed a reduction in scaling and redness after either treatment, compared with animals that had no treatment.
There were also fewer viable MRSP bacteria left on the skin after treatment with Staphylococcus felis C4.
Next steps include plans for a clinical trial to confirm whether this strain can be used to treat MRSP infections in dogs.
“Don’t stop washing your pets to keep these ‘good’ bacteria on them,” Professor Gallo said.
“Skin has evolved to protect the ‘good’ bacteria, so soap and detergents don’t usually wash the good guys off.”
“It may even be possible that living with a healthy cat provides humans with some protection against MRSP, so this may be an argument in support of pet ownership.”
The findings were published in the journal eLife.
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Alan M. O’Neill et al. 2021. Antimicrobials from a feline commensal bacterium inhibit skin infection by drug-resistant S. pseudintermedius. eLife 10: e66793; doi: 10.7554/eLife.66793
Source link: https://www.sci.news/biology/staphylococcus-felis-10185.html
