BACTERIAL BIOFILM FORMATION AND QUORUM SENSING: MOLECULAR MECHANISMS, CLINICAL SIGNIFICANCE, AND ANTI-BIOFILM THERAPEUTIC STRATEGIES

Background: Bacterial biofilms—structured, surface-attached microbial communities encased in a self-produced extracellular polymeric substance (EPS) matrix—represent the predominant mode of bacterial existence in natural and clinical environments. Biofilm-associated infections account for over 65% of all human microbial infections and 80% of chronic infections, are 10–1,000-fold more resistant to antibiotics than planktonic counterparts, and are responsible for the majority of device-related nosocomial infections. Quorum sensing (QS)—the cell density-dependent, signal molecule-mediated gene regulation system that coordinates biofilm formation, virulence factor expression, and antibiotic resistance—is the central molecular regulatory mechanism linking bacterial population density to pathogenic behaviour.