Antibiotic resistance increment is a major problem for the human society nowadays which encourages the efforts to look for new therapeutic alternatives from natural defenses. Synergistic antibacterial activity of epidermin and staphylolysin LasA A against Staphylococcus aureus (Staph aureus), Escherichia coli (E. coli) and Pseudomonas aeruginosa (Ps. aeruginosa) was evaluated. The antibacterial activities of epidermin from Staphylococcus epidermidis (Staph epidermidis) and Staphylolysin (LasA) from Ps. aeruginosa using the agar well diffusion assay were evaluated, and then using the micro dilution method to evaluate the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The checkerboard method and fractional inhibitory concentration (FIC) were used to evaluate the combination between epidermin and LasA toward targeted clinical isolates of Staph aureus, E. coli and Ps. aeruginosa. The results revealed a synergistic effect between epidermin and LasA on all clinical isolates growth. The highest MIC and MBC of epidermin were 36.04 µL/mL and 51.73 µL/mL against Staph aureus; meanwhile, the highest MIC and MBC of LasA were 44.38 µL/mL and 50 µL/mL against Staph aureus. The FICindex revealed synergistic interactions in combination of epidermin and LasA which recorded 0.286 for Staph aureus while for E. coli was 0.327 and for Ps. aeruginosa was 0.390 respectively showing a synergism effect. This study finds that combination of epidermin with LasA had inhibitory activity on the targeted clinical isolate growth, which can be useful for designing and developing alternative therapeutic strategies against pathogens causing wound and burn infections.
