Staphylococcus aureus is a gram-positive, highly pathogenic, opportunistic, multi-drug resistant, and virulent bacteria that cause infections in animals and humans. It can also colonize fish and be maintained in the environment. Possible transmissions from animal to human or vice versa increase the potential spread of infections. Treating those infections is increasingly compromised as S. aureus has a great capacity for acquiring new antibiotic resistance, methicillin-resistant S. aureus (MRSA) being a significant concern. MRSA has been found in fish and shrimp from aquaculture origin and has emerged as a significant animal health problem worldwide, resulting in an economic burden. In humans, S. aureus predominantly causes osteomyelitis, an inflammatory bone disease that leads to progressive bone destruction. Most treatments fail due to the increased resistance of S. aureus against antibiotics, thus raising a global challenge for alternative therapeutic strategies that can be used alone or in combination with conventional antibiotics to treat the disease. One alternative is bacteriophage therapy, which showed promise on an individual case basis but remains limited by the strain specificity of phage infection. Phage endolysins are cell wall degrading peptidoglycan hydrolases (PGHs), enzyme antimicrobials that digest peptidoglycan, the major structural component of the bacterial cell wall. We identified two PGHs that can potentially treat S. aureus infections. We used the pET21a (+) vector to express PGH-6x His tag in BL21 (DE3) E. coli, purified the proteins, and tested against S. aureus clinical strains. Our preliminary data suggests new potential alternatives to antibiotics to treat S. aureus infections.