Inhibition of Biofilm Formation by the Synergistic Action of EGCG-S and Antibiotics

Biofilm, a stress-induced physiological state, is an established means of antimicrobial tolerance. A perpetual increase in multidrug resistant (MDR) infections associated with high mortality and morbidity have been observed in healthcare settings. Multiple studies have indicated that the use of natural products can prevent bacterial growth. Recent studies in the field have identified that epigallocatechin gallate (EGCG), a green tea polyphenol, could disrupt bacterial biofilms. A modified lipid-soluble EGCG, epigallocatechin-3-gallate-stearate (EGCG-S), has enhanced the beneficial properties of green tea. This study focuses on utilizing EGCG-S as a novel synergistic agent with antibiotics to prevent or control biofilm. Different formulations of EGCG-S and selected antibiotics were used to study their combinatorial effects on biofilms produced by five potential pathogenic bacteria, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, and Mycobacterium smegmatis. The crystal violet (CV) assay and the sensitive fluorescence-based resazurin biofilm viability assay were used to assess the biofilm production. Our results identified optimal formulation for each bacterium, effectively inhibiting biofilm formation to an extent of 95–99%. Colony-forming unit (CFU) and cell viability analyses showed a decrease of viable bacteria. These results depict the potential of EGCG-S as a synergistic agent with antibiotics and as an anti-biofilm agent.