Efficacy of phage K-MPs against different strains of S. aureus. A, Xen29. B, SA 46106A. C, SA 46106B. D. SA 19685. E, mixture of four strains of S. aureus (SA Xen29 + SA 46106A + SA 46106B + SA 19685). F, UAMS-1, a clinical isolate of S. aureus, G Methicillin-resistant S. aureus and H, mixture of MRSA and UAMS-1. 100 μL bacterial suspension (1×107 CFU/mL) in LB was treated with MPs or phage K-MPs (2 mg/mL) for 24 hours with intermittent shaking. The suspensions were serially diluted, plated on agar plates, incubated at 37 °C, followed by enumeration of bacterial colonies after 16–20 hours. Dashed line represents limit of detection.****P < 0.0001 via unpaired two-tailed t test.