Biofilm-Associated Infections: Mechanisms of Formation, Resistance, and Emerging Therapeutic Strategies With Special Focus on Biofilm Inhibitors

Biofilms are complex, structured microbial communities enclosed within a self-produced extracellular matrix. This matrix allows them to adhere to a variety of surfaces, including medical devices and human tissues. The formation of biofilms poses a significant challenge in clinical settings due to their inherent resistance to antibiotics and to host immune defenses, thereby contributing to the persistence and chronicity of infections. In recent years, considerable attention has been directed towards the development of biofilm inhibitors as a promising therapeutic strategy to prevent biofilm formation, disrupt established biofilms, and enhance the susceptibility of biofilm-embedded bacteria to conventional antibiotics. The aim of this review is to critically examine the current literature on biofilm inhibitors, focusing on their mechanisms of action, therapeutic potential, and synergistic use with conventional antibiotics. By summarizing existing evidence and highlighting emerging strategies, including quorum-sensing inhibitors, cyclic-di-GMP modulators, enzymatic disruptors, natural compounds, and anti-adhesion molecules, this review seeks to provide a comprehensive understanding of advances in anti-biofilm therapeutics and identify knowledge gaps warranting further investigation. Several classes of biofilm inhibitors have been identified that target key stages in the biofilm lifecycle. These include quorum-sensing inhibitors (QSIs) that block bacterial communication systems, cyclic-di-GMP inhibitors that interfere with intracellular signaling pathways, and enzymatic inhibitors that degrade the structural components of the biofilm matrix, such as extracellular DNA, proteins, and polysaccharides. Natural products, including plant-derived polyphenols, essential oils, and marine compounds, have demonstrated potent anti-biofilm properties by inhibiting bacterial adhesion, modulating gene expression, and reducing the production of extracellular polymeric substances (EPS). Additionally, anti-adhesion molecules, efflux pump inhibitors, iron chelators, and stress response inhibitors have been investigated for their potential to weaken or prevent biofilm development. Combining biofilm inhibitors with antibiotics yields a synergistic effect, significantly enhancing bacterial eradication and reducing the development of resistance. The ongoing exploration and development of biofilm inhibitors hold great promise for advancing future anti-biofilm therapeutics and addressing the challenges posed by biofilm-related infections.