Synergistic Antibacterial Activity of synthesized Graphene Oxide/Chitosan nanocomposite with Rosmarinus officinalis L. Essential Oil against Multidrug-Resistant Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli isolates

Treatment of infections caused by multidrug-resistant bacteria has become a global challenge. The combined therapies involve the simultaneous use of two or more biological agents with different mechanisms of action, which are more effective than traditional treatments for diseases that act only in one way. The aim of this study was synergistic antibacterial activity of synthesized graphene oxide/chitosan (GO/CS) nanocomposite with Rosmarinus officinalis L. essential oil against multidrug-resistant (MDR) bacteria. R. officinalis essential oil was extracted and its chemical compounds were analyzed by gas chromatography and mass spectrometry. The GO/CS nanocomposite was synthesized. The size and structure of the synthesized nanoparticles were evaluated by EDS, XRD, FE-SEM, and FTIR analysis. Antibacterial activity of chitosan, graphene oxide, GO/CS nanocomposite and R. officinalis essential oil was studied by broth microdilution method against 5 MDR isolates of A. baumannii, P. aeruginosa and E. coli. The antimicrobial interaction of the essential oil and GO/CS composite was studied by checkerboard titration method. The results showed that chitosan, graphene oxide and GO/CS had no antimicrobial activity in the studied concentrations. The MIC of R. officinalis essential oil was obtained between 0.12-256 μl/ml. R. officinalis essential oil in combination with GO/CS nanocomposite had a synergistic effect against 5 isolates of P. aeruginosa and 2 isolates of A. baumannii, and caused an additive effect against two isolates of E. coli. Based on the findings of this study, this combination can be effective against some MDR isolates and could be used to treat infections caused by these isolates.