The emergence of multi-drug resistant pathogenic bacteria, coupled with a decline in discovery of new drugs, has gradually steered the world to the doorstep of post-antibiotic era as trivial infections often become untreatable with the existing antibiotics. Therefore, design and development of new therapeutic strategies would be of paramount importance, primarily by interfering with mechanisms leading to drug resistance. Accordingly, researchers are aiming at the restoration of activity of existing antibiotics by using resistance modifying agents (RMA), and looking for suitable secondary plant metabolites to function as RMAs. Plant-derived RMAs are believed to rejuvenate the action of conventional antibiotics via unique mechanisms, as for example, by acting upon bacterial efflux pumps, enhancing membrane permeability, and inhibiting the synthesis of proteins responsible for bacterial resistance. However, due to the lack of adequate pharmacological data, these phytochemicals are yet to be approved for clinical use, despite the upcoming prospect of their therapeutic application. This chapter focuses on the relevant screening strategies to characterise new RMAs from plant constituents exhibiting resistance modifying activity against pathogenic bacteria. Also, the respective mode of synergistic interaction of these agents has been discussed in view of their potential application to supplement the conventional antibiotics against drug-resistant bacterial infections.
Keywords: Antimicrobial resistance, Antibiotic adjuvant, Efflux pump inhibitor, FICI, Isobologram, Plant-derived RMA, Pathogenic bacteria, Phytochemical, Resistance modifying agent, Synergistic interaction.