Characterization and antibacterial efficacy of the broad-host-range phage P108 against biofilm-forming and methicillin-resistant Staphylococcus aureus

• A lytic myovirus, phage P108, capable of targeting methicillin-resistant Staphylococcus aureus (MRSA) strains, was isolated and characterized. • Phylogenetic analysis revealed that phage P108 represents a novel member of the Kayvirus genus within the Herelleviridae family. • Phage P108 effectively lyses 79.2% (95/120) of clinical S. aureus isolates, with a notably high lysis rate of 84.8% (39/46) against MRSA. • Phage P108 exhibits high stability, potent in vitro bactericidal activity, and effective bacterial biofilm clearance, outperforming vancomycin in overall efficacy. Staphylococcus aureus ( S. aureus ) is a widely distributed opportunistic pathogen capable of causing a variety of serious infections, with its antibiotic resistance becoming increasingly prevalent. As natural bactericidal agents, bacteriophages (phages) have emerged as promising therapeutic alternatives to antibiotics. In this study, we isolated a lytic phage P108 capable of targeting methicillin-resistant S. aureus (MRSA) strains. Phage P108 features an icosahedral head with a diameter of approximately 84.7 nm and a contractile tail measuring about 221.5 nm in length. It has a latent period of 20 min and completes lysis within 60 min. Whole-genome sequencing revealed a linear dsDNA genome of 140,807 bp, encoding 226 putative proteins and 3 tRNAs. Four novel structural protein-coding genes were identified. Phylogenetic analysis demonstrated that P108 represents a member of the Herelleviridae family, Kayvirus genus. P108 is capable of lysing 79.2% (95/120) of clinical isolates of S. aureus and demonstrates broad-spectrum lytic activity against MRSA (84.8%, 39/46). Furthermore, phage P108 exhibits high stability, potent in vitro bactericidal activity, and effective bacterial biofilm removal, outperforming vancomycin in overall efficacy. These findings highlight its potential for antibacterial applications and support its development as a novel therapeutic strategy against drug-resistant S. aureus infections.