Essential Oils as Antimicrobial Agents Against WHO Priority Bacterial Pathogens: A Strategic Review of In Vitro Clinical Efficacy, Innovations and Research Gaps

Abstract

The rapid rise of antimicrobial resistance (AMR) has emerged as a critical global health crisis, driven by the widespread emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) pathogens. This growing threat, coupled with the stagnation in the development of novel antibiotics, necessitates the investigation of alternative antimicrobial strategies. Plant-derived essential oils (EOs) have emerged as promising candidates due to their broad-spectrum antibacterial activity, multi-targeted mechanisms, and capacity to enhance the efficacy of existing antibiotics. Recent studies have underscored the potential of EOs in disrupting biofilms, inhibiting quorum sensing, modulating efflux pumps, and reversing resistance in a variety of bacterial pathogens, including those listed as priorities by the World Health Organization. Notably, many of these effects have been demonstrated against resistant strains isolated directly from clinical samples, thereby enhancing the translational significance of EOs. In addition to their antimicrobial properties, advances in analytical, omics-based, and microfluidic technologies have further elucidated the mechanisms of EOs and may accelerate their therapeutic development. Nevertheless, challenges such as variability in composition, lack of standardized testing protocols, and limited in vivo data continue to impede clinical application. Therefore, the aim of this scoping review is to critically examine the advances over the past decade in the antibacterial activity of plant EOs against clinical isolates, with a particular focus on their efficacy against resistant bacterial pathogens and their potential role in combating AMR.