Epigallocatechin Gallate Inhibits Biofilm Production and Attenuates Virulent Factors of Pseudomonas aeruginosa and Psuedomonas fluorescence

Catechins especially Epigallocatechin Gallate (EGCG) and its isomers have been shown to constitute the most important and effective antimicrobial part of tea polyphenols. Antimicrobial effects of EGCG on a variety of pathogens have been published previously. The anti-microbial mechanism of green tea polyphenols has also been studied. Effects of green tea extracts on bacterial surviving tactics such as Quorum Sensing (QS) have showed significant inhibitory effects. However, there are no literatures that demonstrate a quantitative assay that would establish the Minimum Inhibitory Concentration (MIC) that can interfere with QS regulated factors. Also, there is no published data that clearly demonstrates which components of green tea or black tea is responsible for the inhibition of QS-regulated virulence factors. In this study we prove that EGCG which constitutes 5% of dry weight of green tea and 10% in green tea is effective in inhibiting the biofilm production of Psuedomonas aeruginosa and Psuedomonas fluorescens by down-regulating its virulence factors. Our study established a Minimum Inhibitory Concentration (MIC) of 8mM (∼4 mg/ml) concentration of EGCG for inhibition of biofilm production in both organisms. QS regulated virulent factors such as pyocyanin, protease and elastase production also decreased with increase in the EGCG concentration.