Antipathogenic Properties of Green Tea Polyphenol Epigallocatechin Gallate at Concentrations below the MIC against Enterohemorrhagic Escherichia coli O157:H7

Abstract

The inhibitory effects of green tea polyphenol epigallocatechin gallate (EGCG) on virulence phenotypes and gene expression regulated by quorum sensing (QS) in Escherichia coli O157:H7 were demonstrated at concentrations of 1 to 100 microg/ml, which are lower than the MIC (539 +/- 22 microg/ml). At 25 microg/ml, the growth rate was not affected, but autoinducer 2 concentration, biofilm formation, and swarm motility decreased to 13.2, 11.8, and 50%, respectively. Survival at 5 days of nematodes (Caenorhabditis elegans) that were fed the pathogen without and with EGCG were 47.1 and 76%, respectively. Real-time PCR data indicated decreased transcriptional level in many quorum sensing-regulated virulence genes at 25 microg/ml. Our results suggest that EGCG at concentrations below itsMIC has significant antipathogenic effects against E. coli O157:H7.

Role of rifampicin in limiting Escherichia coli O157:H7 Shiga-like toxin expression and enhancement of survival of infected BALB/c mice

“…In light of the reported adverse effects of antibiotic use in human E. coli O157:H7 infections, investigations into therapeutic modes have focused on the use of natural products and have ranged from testing green tea components [33] to more recently American cranberry constituents [34]. However, these studies were mostly performed at the in vitro level.…”

Inhibiting Microbial Toxins Using Plant-Derived Compounds and Plant Extracts

“…Likewise, a decrease in toxin production has been reported following treatment with plant extracts such as catechin [100], epigallocatechin [101], cinnamon bark oil, cinnamaldehyde, and eugenol [102]. In addition, plant extracts, including green tea extracts, tea catechins, and green tea polyphenol were found to modulate other virulence attributes in EHEC such as biofilm formation, swarming motility and quorum sensing [103]. Since the concentrations of plant compounds used in above studies were below MIC, the effects observed were not due to reduction in cell number, but probably due to modulation of gene transcription in cells.…”

Tea Catechin EGCg Suppresses the mgl Gene Associated with Halitosis

“…Although the suppression of transcriptional levels of various quorumsensing-regulated virulence genes by EGCg has been reported in Escherichia coli 0157:H7 (Lee et al, 2009) Figure 4. Effects of increasing concentrations of EGCg on METase protein expression in P. gingivalis W83.…”