Anti-quorum sensing effects of licochalcone A and epigallocatechin-3-gallate against Typhimurium isolates from poultry sources.

Quorum sensing (QS) is a cell density-dependent mechanism used by many pathogenic bacteria for regulating virulence gene expression. Inhibition or interruption of QS by medicinal plant remedies has been suggested as a new strategy for fighting against antibiotic-resistant bacteria. This study aimed to assess the impact of sub-inhibitory concentrations of licochalcone A (LAA) and epigallocatechin-3-gallate (EGCG) as natural plant products on the QSassociated genes ( and ) expression. The PCR test was used to confirm the presence of and genes in 23 . Typhimurium isolates from poultry. The quantitative real-time PCR assay was used to analyze the expression of and in . Typhimurium isolates in response to the treatment with sub-inhibitory concentrations of LAA and EGCG at 45-min time point. All . Typhimurium isolates showed the presence of and genes (100%). As result, the expression of QS-related genes was significantly reduced in Typhimurium isolates following treatment with LAA and EGCG. In conclusion, LAA and EGCG showed anti-QS activity with down-regulation of both and genes in Typhimurium, suggesting potential therapeutic use of them against salmonellosis. However, it must be pointed out that the safety and efficiency of these compounds need more thorough research.