Staphylococcus aureus is one of the leading causes of global mortality due to bacterial infection. Antibiotic-resistant forms such as methicillin-resistant S. aureus (MRSA) are more difficult to treat, which poses an increased risk of complications to patients. Multiple organizations predict that by 2050, antibiotic-resistant bacterial infections could cause 10 million deaths a year. Therefore, developing effective treatments for antibiotic-resistant infections is urgently needed. Recent evidence shows that bacteriophage (phages, viruses that infect bacteria) therapy may represent a viable and successful solution to this emerging crisis. We describe the isolation, characterization, and optimization of bacteriophages capable of infecting a clinical isolate of MRSA from a pediatric patient suffering from osteomyelitis. Although isolating bacteriophages from environmental sources capable of infecting the clinical strain was challenging, ultimately, we succeeded in finding two bacteriophages from commercial bacteriophage cocktails. The two isolated bacteriophages formed plaques efficiently on the clinical isolate at 30 °C, but not at 37 °C. Through repetitive rounds of culturing at 37 °C, we isolated a mutant bacteriophage that infects the clinical isolate efficiently at 37 °C. Future experiments will utilize the optimized bacteriophage to study its therapeutic potential in a mouse-infection model of osteomyelitis.