Antimicrobials from a feline skin commensal bacterium inhibit skin colonization and infection by drug-resistant S. pseudintermedius

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is an
important emerging zoonotic pathogen that causes severe skin infections.
To combat infections from drug-resistant bacteria, the transplantation of
commensal antimicrobial bacteria as a therapeutic has shown clinical
promise. We screened a collection of diverse staphylococcus species from
domestic dogs and cats for antimicrobial activity against MRSP. A unique
strain (S. felis C4) was isolated from feline skin that inhibited MRSP and
multiple gram-positive pathogens. Competition experiments in mice showed
that S. felis significantly reduced MRSP skin colonization and an
antimicrobial extract from S. felis significantly reduced necrotic skin
injury from MRSP infection. Fluorescence and electron microscopy revealed
that S. felis antimicrobials disrupted bacterial but not eukaryotic cell
membranes. LC/MS identified several S. felis phenol-soluble modulin beta
(PSMβ) peptides that exhibited antimicrobial and anti-inflammatory
activity. These findings indicate a feline commensal bacterium that could
be utilized in bacteriotherapy against difficult-to-treat animal and human
skin infections.