Bacteria Found on Cats Could Help Treat Skin Infection

Researchers at the University of California San Diego School of Medicine used bacteria found on healthy cats to successfully treat a skin infection on mice. These bacteria may serve as the basis for new therapeutics against severe skin infections in humans, dogs, and cats. The study was published in eLife today. 

“Our health absolutely depends on these ‘good’ bacteria,” said lead researcher Richard Gallo. “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.” The team focused on MRSP, an emerging zoonotic pathogen that can cause severe atopic dermatitis or eczema. Since MRSP is resistant to common antibiotics, it has been difficult to treat in clinical and veterinary settings. 

To address this, researchers first 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 called Staphylococcus felis (S. felis) that was especially good at inhibiting MRSP growth. They found that this special strain of S. felis 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,” said Gallo. “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.”

Once the team established how S. felis kills the MRSP, their next step was to see whether it could work as a therapy on a live animal. The team exposed mice to the most common form of the pathogen and then added either S. felis bacteria 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 S. felis. “It may even be possible that living with a healthy cat provides humans with some protection against MRSP,” Gallo concluded, “so this may be an argument in support of pet ownership.”