Efficacy of P128 gel formulation applied to S. aureus on agar surface. A hydrogel formulation containing P128 protein (100 to 1.56 μg/mL) was tested for bactericidal activity when applied topically on S. aureus strain BK#13237 cultured on LB agar: (a) 103 CFU/well, (b) 102 CFU/well. Well #1 represents the media control, and well #2 represents the cell control. In both (a) and (b), P128 gel preparations (100-1.56 μg/mL) were added to wells #3-9; P128 protein formulated in physiological saline (100 μg/mL) was added in well #10 as a positive control; buffer gel was added to well #11 as a negative control. INT dye was added to the visualize growth of the surviving bacteria.