Synergistic Effect of Rhamnolipid in Nano-Chitosan With Antibiotics Against Multidrug Resistance Skin Pathogens

This study was aimed to purify and characterize the rhamnolipid biosurfactant produced by an environmental isolate of P.aeruginosa (PO10), and to evaluate its antibacterial activity alone in combination with chitosan as nanoparticles. The isolate showed strong hemolytic activity (36.6mm clear zone), high emulsification index (E24%=66). Rhamnolipid was extracted and purified using chloroform: methanol (2:1) solvent system and silica gel column chromatography (3.5 x 30 cm), and was characterized by FTIR and GC-MS. The MIC values of rhamnolipid were 12.5mg/ml for both P.aeruginosa and S.aureus. Chitosan/rhamnolipid nanoparticles (C/RL-NPs) were synthesized via ionic gelation and characterized by UV-Vis, FTIR, AFM, Zeta potential (+39mV), and FESEM (44.78-60.71 nm, spherical shape).These analyses confirmed the successful formation and high stability of the C/RL-NPs. The MIC of C/RL-NPs was reduced to 1.25mg/ml. This study is the first to investigate the synergistic effect of C/RL-NPs in combination with antibiotics, resulted in significant increases in inhibition zones against both pathogenic isolate of P.aeruginosa and S.aureus compared to antibiotics or nanoparticles alone.