Olive Leaf Extract Modulates Quorum Sensing Genes and Biofilm Formation in Multi-Drug Resistant Pseudomonas aeruginosa

Abstract

Biofilm acts as a complex barrier against antibiotics. In this study, we investigated the inhibitory activities of Olea europaea (olive) leaves Camellia sinensis (green tea), Styrax benzoin, Ocimum basilicum, Humulus lupulus, Ruta graveolens, and Propolis extracts on the biofilm formation, pyocyanin production, and twitching motility of Pseudomonas aeruginosa isolates. Moreover, we investigated the effect of olive leaf extract on the transcription of some biofilm related genes. A total of 204 isolates of Pseudomonas were collected from different Egyptian hospitals. A susceptibility test, carried out using the disc diffusion method, revealed that 49% of the isolates were multidrug-resistant. More than 90% of the isolates were biofilm-forming, of which 26% were strong biofilm producers. At subinhibitory concentrations, green tea and olive leaf extracts had the highest biofilm inhibitory effects with 84.8% and 82.2%, respectively. The expression levels of lasI, lasR, rhlI, and rhlR treated with these extracts were significantly reduced (p < 0.05) by around 97–99% compared to untreated isolates. This study suggests the ability of olive leaf extract to reduce the biofilm formation and virulence factor production of P. aeruginosa through the down regulation of quorum sensing (QS) genes. This may help in reducing our dependence on antibiotics and to handle biofilm-related infections of opportunistic pathogens more efficiently.

Phytochemical Profiling of Lavandula coronopifolia Poir. Aerial Parts Extract and Its Larvicidal, Antibacterial, and Antibiofilm Activity Against Pseudomonas aeruginosa

“…Clinical isolates of Pseudomonas aeruginosa were collected from burn wounds, otitis media, and urine as previously described [ 26 ] and were kept for scientific research. The isolates were grown on Tryptic soya agar (TSA) (Difco TM , Strasbourg, France) for 24 h at 37 °C, then one single colony of each isolate was inoculated into 2 mL Tryptic soya broth (TSB) (Difco TM , France) with overnight incubation at 37 °C.…”

“…Clinical isolates of Pseudomonas aeruginosa were collected from burn wounds, otitis media, and urine as previously described [26] and were kept for scientific research. The isolates were grown on Tryptic soya agar (TSA) (Difco TM , Strasbourg, France) for 24 h at 37 • C, then one single colony of each isolate was inoculated into 2 mL Tryptic soya broth (TSB) (Difco TM , France) with overnight incubation at 37 • C. The samples were cultivated on Cetrimide agar media, after which the isolated species were identified by morphology (pale yellow colonies on MacConkey and green exopigment on Cetrimide agar), Gram staining (Gram-negative bacilli), and biochemical reactions (oxidase-positive).…”

Exploring the Antivirulence Activity of Pulverulentone A, a Phloroglucinol-Derivative from Callistemon citrinus Leaf Extract, against Multi-Drug Resistant Pseudomonas aeruginosa

“…In general, phytochemicals and plant-derived substances are well known for their antimicrobial and antivirulence activities. El-Sayed and co-workers [ 31 ] studied the effect of some plant extracts (ethanolic extracts of olive leaf and green tea) on the virulence-associated traits of the same strains of P. aeruginosa employed in this study. They reported P. aeruginosa QS genes to undergo down-regulation upon treatment with olive leaf and green tea extracts.…”

“…Ten clinical and environmental isolates of MDR Pseudomonas aeruginosa were used in this study. The clinical isolates were collected in a previous study from patients in different hospitals in Cairo and Alexandria, Egypt [ 31 ]. The isolates were cryopreserved as glycerol stock.…”

The effect of Zinc Oxide nanoparticles on Pseudomonas aeruginosa biofilm formation and virulence genes expression

“…P. aeruginosa recruits at least four different QS networks interrelated to each other, namely las, rhl, iqs, and pqs. These systems possess transcriptional regulators LasR, RhlR, IqsR, and PqsR, respectively, which trigger the expression of selected genes linked to virulence [2]. Increased resistance to antimicrobial agents is a major public health problem worldwide [3].…”