In Egypt, treating SA/MRSA infections using prescribed antibiotics are becoming increasingly challenging. Not just in Egypt, but globally as well, the crisis of antibiotic-resistant bacteria must be addressed immediately; consequently, it is now imperative to look for alternatives.  One of the most promising solutions in this context is bacteriophage. Finding a lytic phage that would allow us to target these bacteria and their biofilm was therefore our goal. Our research revealed that while resistance to other antibiotics varied, all strains of S. aureus exhibited resistance to aminoglycoside. Among isolated phages, SAPI-4 phage (member of Myoviridae family) has the widest host range, as it was able to infect 100% of S. aureus with high efficiency of plating (EOP). SAPI-4 phage significantly (p < 0.05) stable in the acidic circumstances, but at pH 11, after 24 h, about 50% of its infectivity was decreased. Furthermore, SAPI-4 shown superior ability to significantly (p < 0.05) reduce S. aureus in TSB media, raw milk and in both short and long-time storage with high phage stability. In short-time experiment, SAPI-4-treated samples showed a count of 0.46 ± 0.04 Log₁₀ CFU/cm², compared to 6.21 ± 0.97 Log₁₀ CFU/cm² in untreated samples. Furthermore, in the long-term experiment (at day 21), the count of treated sample was 0.97 ± 0.03 Log₁₀ CFU/cm², compared to 5.71 ± 0.09 Log₁₀ CFU/cm² of untreated sample.  At 10⁷ PFU/mL, SAPI-4 was able to eradicate 87%, 93%, 84%, and 91% of the biofilms of SAC9, SAM7, ASC14, and SAC1, respectively. This suggests that the phage's effectiveness against S. aureus biofilms. These outcomes show promise for the SAPI-4 ability to lessen S. aureus' negative impacts and biofilm formation.