We determined the number of viable S. aureus cells remaining at different time intervals after
adding P128 protein. Figure 2 shows the time-kill curves of P128 for six representative strains of S. aureus, which included five MEK162 MRSA strains and one MSSA strain. P128 showed rapid, dose-dependent bactericidal activity against the MSSA and MRSA strains tested, killing of 99.99% of cells in all six strains tested within 1 h at the respective MIC concentration. At the MIC, growth was inhibited up to 24 h for all five MRSA strains and up to 8 h for the MSSA strain (BK#9918). However, the cells of BK#9918 that grew after 8 h were susceptible to P128 (data not shown). Since a concentration 4× the MIC inhibited growth of this strain for up to 24 h, we surmised that higher concentrations of P128 or repeated treatments may be required in such GF120918 price cases. Figure 2 Kill-kinetics of P128 on S. aureus strains. Time-kill curves of P128 at three different concentrations (MIC, MIC × 4, and MIC × 16) on five MRSA and one MSSA strains are shown. Cell control was maintained simultaneously for each strain. Efficacy of P128 gel formulation applied to S. aureus on agar surface The efficacy of P128 hydrogel was tested on solid culture medium to
simulate the conditions of topical nasal application. The assay format was designed to check availability of the protein when applied as a gel formulation. The objective was also to test efficacy of P128 gel applied to a surface where low numbers of bacterial cells are present. We have used a range of 100-1 μg/mL of protein concentration in the gel formulation. P128 gel showed complete clearance at concentrations up to 1.56 μg/mL (Figure 1). Bactericidal activity of P128 against S. aureus COL in SNF Functional efficiency and structural stability of enzymes can generally be influenced by pH, temperature, and the composition and concentrations
of metal or inorganic ions in the reaction milieu. Our Tariquidar price primary concern was that monovalent and divalent Arachidonate 15-lipoxygenase ions present in nasal fluid may have a deleterious effect on P128 activity. We therefore evaluated the activity of P128 in a composition that simulated the ionic content of normal human nasal fluid. We found that P128 reduced the staphylococcal viable count (CFU) by five orders of magnitude in SNF, comparable to the activity observed in case of P128 in physiological saline. Cells incubated in SNF that did not contain P128 were unaffected (Figure 3). These results indicate that the protein would not be influenced by the ionic content of human nasal fluid. Figure 3 P128 activity in simulated nasal fluid. Bactericidal activity of P128 against S. aureus strain COL was tested under conditions simulating the ionic composition of human nasal fluid. Efficacy of P128 gel on nasal Staphylococci in their native physiological state Secreted products and components such as exotoxins, exoenzymes, surface-associated adhesins, and capsular polysaccharide play a role modulating host responses to S.