Staphylococcus hominis A9

**Staphylococcus hominis A9** is a topical live biotherapeutic product composed of a selected human skin commensal bacterium, *Staphylococcus hominis* strain A9, being developed for **atopic dermatitis**. The program originated from UC San Diego research and has been associated with MatriSys Bioscience, with Phase 1 clinical evaluation also sponsored through the National Institute of Allergy and Infectious Diseases. Mechanistically, ShA9 is intended to remodel the atopic skin microbiome by **selectively suppressing *Staphylococcus aureus*** through secreted **lantibiotic antimicrobial peptides** and by **inhibiting *S. aureus* agr quorum sensing**, thereby reducing expression of inflammatory virulence factors including **PSMα**. In preclinical models it reduced *S. aureus* burden and skin inflammation, and in a first-in-human randomized Phase 1 trial in adults with *S. aureus*-positive atopic dermatitis it met the primary safety endpoint, reduced *S. aureus* on skin, and showed signals of clinical benefit particularly in patients colonized by *S. aureus* strains susceptible to ShA9 killing. Earlier clinical formulations used a topical lotion/vehicle with live bacteria, while later company materials describe a stabilized lyophilized topical preparation.

Other names

S. hominis A9Staphylococcus hominis strain A9Staphylococcus hominis universal strain A9