Activity of Cinnamaldehyde on Quorum Sensing and Biofilm Susceptibility to Antibiotics in Pseudomonas aeruginosa

Abstract

Quorum sensing (QS) plays an important role during infection for the opportunistic human pathogen Pseudomonas aeruginosa. Quorum sensing inhibition (QSI) can disrupt this initial event of infection without killing bacterial cells, and thus QS inhibitors have been suggested as novel approaches for anti-infective therapy. Cinnamaldehyde (CAD) is a P. aeruginosa biofilm inhibitor and disperser of preformed biofilms. In this study, the combined use of CAD and colistin (COL) revealed a synergistic activity, but this was not the case for CAD combined with carbenicillin, tobramycin (TOB), or erythromycin in checkerboard assays for P. aeruginosa. CAD demonstrated QSI activity by repression of the expression of lasB, rhlA and pqsA in GFP reporter assays. Approximately 70% reduction in GFP production was observed with the highest CAD concentration tested in all the QS reporter strains. TOB also showed strong QSI when combined with CAD in reporter assays. Combination treatments revealed an additive activity of CAD with COL and TOB in biofilm inhibition (75.2% and 83.9%, respectively) and preformed biofilm dispersion (~90% for both) when compared to the individual treatments. Therefore, a proposed method to mitigate P. aeruginosa infection is a combination therapy of CAD with COL or CAD with TOB as alternatives to current individual drug therapies.

Antivirulence Properties of a Low-Molecular-Weight Quaternized Chitosan Derivative against Pseudomonas aeruginosa

“…In the era of antimicrobial resistance, antivirulence strategies have been endorsed as an attractive approach to control bacterial infections. Instead of imposing a selective pressure on bacterial growth, many virulence-suppressing compounds can attenuate the production of virulence factors and QS-based bacterial communication, disarming the pathogens and leading to reduced pathogenicity [ 10 , 12 , 42 ].…”

“…Several synthetic and natural compounds have shown efficacy as antibiofilm and anti-QS agents [ 11 , 12 ]. Among them, Chitosan has recently attracted much interest as evidence is accumulating that the biopolymer extracted from different sources may interfere with QS and biofilm formation of bacterial pathogens [ 13 , 14 ].…”

Antifungal Activity of Propyl Disulfide from Neem (Azadirachta indica) in Vapor and Agar Diffusion Assays against Anthracnose Pathogens (Colletotrichum gloeosporioides and Colletotrichum acutatum) in Mango Fruit

“…Recently natural plant extracts have become of great interest to researchers due to their volatile nature, aroma, antioxidant and antimicrobial properties [ 6 , 7 ]. Further, plant disease management with plant essential oils has been recognized as one of the best approaches [ 8 ].…”

Combined Treatment of 6-Gingerol Analog and Tobramycin for Inhibiting Pseudomonas aeruginosa Infections

“…They confirmed that combined treatment downregulated QS system-associated gene expression more effectively. Furthermore, Topa et al proposed a combination therapy of cinnamaldehyde with tobramycin as an alternative to mitigate P. aeruginosa infections ( 42 ). Tobramycin showed strong QS inhibitory activity when combined with cinnamaldehyde.…”