Isolation and Characterization of Broad-Host-Range S. aureus Bacteriophages with Antibiofilm and Cross-Species Activity

Staphylococcus aureus and coagulase-negative staphylococci (CoNS) pose significant challenges to antimicrobial therapy, particularly in the context of drug-resistant infections. Our study investigates the potential of S. aureus bacteriophages as therapeutic agents against biofilm-associated staphylococcal pathogens. A total of nine phages were isolated from clinical and environmental sources, among which three, designated APTC-SA-10, APTC-SA-11, and APTC-SA-14, exhibited the broadest host range, lysing up to 78% of 60 tested S. aureus clinical isolates. Genomic sequencing indicated the phages were strictly lytic, belonging to the Kayvirus genus of the Herelleviridae family. In addition to the wide host range, they demonstrated strong antibiofilm activity in vitro reducing the biofilm viability by ~6 logs and the biomass by ~90%. The phages demonstrated cross-species lytic activity against non-aureus staphylococci (NAS) including S. epidermidis (15%), S. lugdunensis (88%), and S. capitis (67% of the tested isolates). These properties underscore their potential utility in the treatment of polymicrobial infections involving both coagulase-positive and -negative staphylococci. Collectively, these findings support further investigation of these bacteriophages as promising candidates for phage therapy, particularly in the context of biofilm-mediated staphylococcal infections.