Abstract
The relentless rise of antimicrobial resistance (AMR) has outpaced the discovery of new antibiotics, creating an urgent need for therapeutic paradigms that do not rely on killing or arresting the growth of bacteria. Quorum sensing (QS) is a cell-density-dependent communication system through which bacteria coordinate collective behaviours such as virulence-factor production, biofilm formation, motility, and stress adaptation by synthesising, releasing, and detecting diffusible signal molecules. Because many of these coordinated behaviours drive pathogenicity and reduce the efficacy of conventional antibiotics, interrupting bacterial communication has emerged as an attractive anti-virulence strategy. Quorum-sensing inhibition, also termed quorum quenching, disarms pathogens by blocking signal biosynthesis, enzymatically degrading signal molecules, or antagonising signal receptors, thereby switching off the genetic programmes that underlie infection without imposing the strong selective pressure exerted by bactericidal agents. This review synthesises the molecular architecture of the principal QS systems in Gram-negative and Gram-positive bacteria, explains the mechanistic link between quorum sensing, biofilm formation, and drug resistance, and critically surveys the major classes of quorum-sensing inhibitors, including natural products, synthetic analogues, quorum-quenching enzymes, and nanoparticle-based platforms. Particular attention is given to the synergy between quorum-sensing inhibitors and established antibiotics, which can restore susceptibility in otherwise recalcitrant biofilm infections. The review further examines the translational hurdles that currently limit clinical adoption, including the risk of resistance to inhibitors, pharmacokinetic and delivery challenges, and the need for robust in-vivo validation. It concludes that quorum-sensing inhibition, especially when deployed in combination with conventional therapy, represents a biologically rational and clinically promising component of the future anti-infective armamentarium.