A review on novel strategies to combat multidrug resistance in pathogenic bacteria exploiting synergism between essential oil and antibiotics.

The rapid rise of multidrug-resistant (MDR) bacteria has rendered many conventional antibiotics ineffective, therefore urging the need for novel treatment approaches. In the last few years, essential oils have been studied for their potential to enhance the effectiveness of conventional antibiotics. Essential oils contain several bioactive compounds, such as terpenes and phenols. In this review we discuss how the combination of essential oils with antibiotics can be used to improve their action against antibiotic resistant bacteria, including Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Combination of essential oils with antibiotics can make bacterial membranes more permeable; inhibit efflux pumps that are involved in the extrusion of drugs; interfere with bacterial biofilm formation; and decrease bacterial virulence and communication (quorum sensing). Laboratory studies, including checkerboard and time–kill assays, demonstrate that some essential oils, such as lavender, thyme, oregano, and cinnamon, can significantly reduce the antibiotic doses required to inhibit bacterial growth. Such combinations restore the effectiveness of antibiotics but, most importantly minimize side effects and increase the scope of treating bacterial infections. However, the standardization and formulations of essential oils needs further study on safety and application in a clinical setting. Upcoming technologies, including nanocarrier-based delivery systems, may enable the development of essential oil-antibiotic synergy into a practical, feasible approach in the fight against antimicrobial resistance.