Staphylococcal phages as agents of evolution and innovation: From gene flow to next-generation therapeutics.

Staphylococcus species include both well-known pathogens and overlooked reservoirs of antimicrobial resistance. With rising resistance rates and limited treatment options, especially for methicillin-resistant strains, interest in alternative therapies has resurged. Among them, bacteriophages (phages) are promising biological agents due to their high specificity, low toxicity, ability to disrupt biofilms, and co-evolution with bacterial hosts. This review explores the biology, pan-genomics, diversity, and therapeutic relevance of staphylococcal phages. We revisit their historical discovery and re-emergence as tools against multidrug-resistant infections, highlighting morphological features, replication strategies, and recent taxonomic updates. Genomic analyses reveal distinct clusters of genome sizes, rare presence of resistance genes, and implications of transduction, bacterial defense systems, and phage-encoded anti-defense mechanisms. Preclinical studies show broad host range and synergistic activity with diverse antimicrobial agents, while engineered phage enzymes expand therapeutic possibilities. Clinical evidence, though limited, supports safety and efficacy in compassionate-use cases and early trials targeting Staphylococcus. Finally, we examine business models translating phage innovation into applied therapies, emphasizing regulatory, logistical, and financial challenges. In this broader context, phage technologies are not just alternatives to antibiotics-they represent an opportunity for innovation in global health. Their full potential depends on coordinated actions across science, industry, and policy.