Expression of Quorum Sensing and Virulence Factors Are Interlinked in Pseudomonas aeruginosa: an in vitro Approach

2011 ◽  
pp. 116-125 ◽  
Author(s):  
Ravi Kumar Gupta ◽  
Sania Setia ◽  
Kusum Harjai
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors

scholarly journals Calpurnia aurea (Aiton) Benth Extracts Reduce Quorum Sensing Controlled Virulence Factors in Pseudomonas aeruginosa

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2283
Author(s):  
Sekelwa Cosa ◽  
Jostina R. Rakoma ◽  
Abdullahi A. Yusuf ◽  
Thilivhali E. Tshikalange
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Molecular Docking ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Promising Alternative ◽  
The Individual

Pseudomonas aeruginosa is the causative agent of several life-threatening human infections. Like many other pathogens, P. aeruginosa exhibits quorum sensing (QS) controlled virulence factors such as biofilm during disease progression, complicating treatment with conventional antibiotics. Thus, impeding the pathogen’s QS circuit appears as a promising alternative strategy to overcome pseudomonas infections. In the present study, Calpurnia aurea were evaluated for their antibacterial (minimum inhibitory concentrations (MIC)), anti-quorum sensing/antivirulence (AQS), and antibiofilm potential against P. aeruginosa. AQS and antivirulence (biofilm formation, swimming, and swarming motility) activities of plant extracts were evaluated against Chromobacterium violaceum and P. aeruginosa, respectively. The in vitro AQS potential of the individual compounds were validated using in silico molecular docking. Acetone and ethanolic extracts of C. aurea showed MIC at 1.56 mg/mL. The quantitative violacein inhibition (AQS) assay showed ethyl acetate extracts as the most potent at a concentration of 1 mg/mL. GCMS analysis of C. aurea revealed 17 compounds; four (pentadecanol, dimethyl terephthalate, terephthalic acid, and methyl mannose) showed potential AQS through molecular docking against the CviR protein of C. violaceum. Biofilm of P. aeruginosa was significantly inhibited by ≥60% using 1-mg/mL extract of C. aurea. Confocal laser scanning microscopy correlated the findings of crystal violet assay with the extracts significantly altering the swimming motility. C. aurea extracts reduced the virulence of pseudomonas, albeit in a strain- and extract-specific manner, showing their suitability for the identification of lead compounds with QS inhibitory potential for the control of P. aeruginosa infections.

scholarly journals Quorum sensing and virulence of Pseudomonas aeruginosa during urinary tract infections

2012 ◽  
Vol 6 (06) ◽  
pp. 501-507 ◽  
Author(s):  
Sezgi Senturk ◽  
Seyhan Ulusoy ◽  
Gulgun Bosgelmez-Tinaz ◽  
Aysegul Yagci
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Urinary Tract ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Urinary Tract Infections ◽  
Clinical Isolates ◽  
Pcr Analysis ◽  
Signal Molecules ◽  
Tract Infections

Introduction: In the opportunistic pathogen Pseudomonas aeruginosa, the production of several virulence factors depends on quorum sensing (QS) involving N-acylhomoserine lactone signal molecules. In vitro studies have suggested that the QS system is crucial in the pathogenesis of P. aeruginosa. However, it is unclear whether QS systems of P. aeruginosa play the same role during infections. Methodology:  In this study, to explore the contribution of QS systems to the pathogenesis of P. aeruginosa during urinary tract infections, we collected 82 clinical isolates. Detection of N-acyl-homoserine lactones (C12-HSL and C4-HSL) was performed on agar plates employing biosensor strains C. violaceum. Elastase and biofilm production were determined spectrophotometrically. QS genes were detected by PCR and subsequently underwent sequencing. Results and conclusion:  Six isolates were found to be negative in the production of both C12-HSL and C4-HSL and all virulence factors tested.  PCR analysis of these isolates revealed that four isolates contained all four QS genes while one isolate was negative for lasR gene, and one isolate negative for lasI, lasR and rhlR genes. Sequence analyses of these isolates showed that the lasR, lasI, rhlR and rhlI genes had point mutations. The combination of these mutations probably explains their C12-HSL, C4-HSL and virulence factor deficiencies. Results of this study suggest that QS deficient clinical isolates occur and are still capable of causing clinical infections in humans. 

scholarly journals Pseudomonas aeruginosa PA80 is a cystic fibrosis isolate deficient in RhlRI quorum sensing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Syed A. K. Shifat Ahmed ◽  
Michelle Rudden ◽  
Sabrina M. Elias ◽  
Thomas J. Smyth ◽  
Roger Marchant ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Genomic Islands ◽  
Clinical Strain ◽  
Whole Genome ◽  
Synonymous Mutations ◽  
Wide Range

AbstractPseudomonas aeruginosa uses quorum sensing (QS) to modulate the expression of several virulence factors that enable it to establish severe infections. The QS system in P. aeruginosa is complex, intricate and is dominated by two main N-acyl-homoserine lactone circuits, LasRI and RhlRI. These two QS systems work in a hierarchical fashion with LasRI at the top, directly regulating RhlRI. Together these QS circuits regulate several virulence associated genes, metabolites, and enzymes in P. aeruginosa. Paradoxically, LasR mutants are frequently isolated from chronic P. aeruginosa infections, typically among cystic fibrosis (CF) patients. This suggests P. aeruginosa can undergo significant evolutionary pathoadaptation to persist in long term chronic infections. In contrast, mutations in the RhlRI system are less common. Here, we have isolated a clinical strain of P. aeruginosa from a CF patient that has deleted the transcriptional regulator RhlR entirely. Whole genome sequencing shows the rhlR locus is deleted in PA80 alongside a few non-synonymous mutations in virulence factors including protease lasA and rhamnolipid rhlA, rhlB, rhlC. Importantly we did not observe any mutations in the LasRI QS system. PA80 does not appear to have an accumulation of mutations typically associated with several hallmark pathoadaptive genes (i.e., mexT, mucA, algR, rpoN, exsS, ampR). Whole genome comparisons show that P. aeruginosa strain PA80 is closely related to the hypervirulent Liverpool epidemic strain (LES) LESB58. PA80 also contains several genomic islands (GI’s) encoding virulence and/or resistance determinants homologous to LESB58. To further understand the effect of these mutations in PA80 QS regulatory and virulence associated genes, we compared transcriptional expression of genes and phenotypic effects with isogenic mutants in the genetic reference strain PAO1. In PAO1, we show that deletion of rhlR has a much more significant impact on the expression of a wide range of virulence associated factors rather than deletion of lasR. In PA80, no QS regulatory genes were expressed, which we attribute to the inactivation of the RhlRI QS system by deletion of rhlR and mutation of rhlI. This study demonstrates that inactivation of the LasRI system does not impact RhlRI regulated virulence factors. PA80 has bypassed the common pathoadaptive mutations observed in LasR by targeting the RhlRI system. This suggests that RhlRI is a significant target for the long-term persistence of P. aeruginosa in chronic CF patients. This raises important questions in targeting QS systems for therapeutic interventions.

scholarly journals Revisiting the quorum-sensing hierarchy in Pseudomonas aeruginosa: the transcriptional regulator RhlR regulates LasR-specific factors

Microbiology ◽  
2009 ◽  
Vol 155 (3) ◽  
pp. 712-723 ◽  
Author(s):  
Valérie Dekimpe ◽  
Eric Déziel
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Transcriptional Regulator ◽  
Homoserine Lactone ◽  
The Other ◽  
Virulence Determinants ◽  
Late Stationary Phase ◽  
Regulatory Systems ◽  
Specific Factors

Pseudomonas aeruginosa uses the two major quorum-sensing (QS) regulatory systems las and rhl to modulate the expression of many of its virulence factors. The las system is considered to stand at the top of the QS hierarchy. However, some virulence factors such as pyocyanin have been reported to still be produced in lasR mutants under certain conditions. Interestingly, such mutants arise spontaneously under various conditions, including in the airways of cystic fibrosis patients. Using transcriptional lacZ reporters, LC/MS quantification and phenotypic assays, we have investigated the regulation of QS-controlled factors by the las system. Our results show that activity of the rhl system is only delayed in a lasR mutant, thus allowing the expression of multiple virulence determinants such as pyocyanin, rhamnolipids and C4-homoserine lactone (HSL) during the late stationary phase. Moreover, at this stage, RhlR is able to overcome the absence of the las system by activating specific LasR-controlled functions, including production of 3-oxo-C12-HSL and Pseudomonas quinolone signal (PQS). P. aeruginosa is thus able to circumvent the deficiency of one of its QS systems by allowing the other to take over. This work demonstrates that the QS hierarchy is more complex than the model simply presenting the las system above the rhl system.

scholarly journals A Novel Infection Protocol in Zebrafish Embryo to Assess Pseudomonas aeruginosa Virulence and Validate Efficacy of a Quorum Sensing Inhibitor In Vivo

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 401
Author(s):  
Pauline Nogaret ◽  
Fatima El El Garah ◽  
Anne-Béatrice Blanc-Potard
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Animal Model ◽  
Quorum Sensing ◽  
Drug Testing ◽  
Drug Efficacy ◽  
Embryo Viability ◽  
Immersion Method ◽  
Opportunistic Human Pathogen

The opportunistic human pathogen Pseudomonas aeruginosa is responsible for a variety of acute infections and is a major cause of mortality in chronically infected cystic fibrosis patients. Due to increased resistance to antibiotics, new therapeutic strategies against P. aeruginosa are urgently needed. In this context, we aimed to develop a simple vertebrate animal model to rapidly assess in vivo drug efficacy against P. aeruginosa. Zebrafish are increasingly considered for modeling human infections caused by bacterial pathogens, which are commonly microinjected in embryos. In the present study, we established a novel protocol for zebrafish infection by P. aeruginosa based on bath immersion in 96-well plates of tail-injured embryos. The immersion method, followed by a 48-hour survey of embryo viability, was first validated to assess the virulence of P. aeruginosa wild-type PAO1 and a known attenuated mutant. We then validated its relevance for antipseudomonal drug testing by first using a clinically used antibiotic, ciprofloxacin. Secondly, we used a novel quorum sensing (QS) inhibitory molecule, N-(2-pyrimidyl)butanamide (C11), the activity of which had been validated in vitro but not previously tested in any animal model. A significant protective effect of C11 was observed on infected embryos, supporting the ability of C11 to attenuate in vivo P. aeruginosa pathogenicity. In conclusion, we present here a new and reliable method to compare the virulence of P. aeruginosa strains in vivo and to rapidly assess the efficacy of clinically relevant drugs against P. aeruginosa, including new antivirulence compounds.

scholarly journals The YebC Family Protein PA0964 Negatively Regulates the Pseudomonas aeruginosa Quinolone Signal System and Pyocyanin Production

2008 ◽  
Vol 190 (18) ◽  
pp. 6217-6227 ◽  
Author(s):  
Haihua Liang ◽  
Lingling Li ◽  
Zhaolin Dong ◽  
Michael G. Surette ◽  
Kangmin Duan
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Response Regulator ◽  
Initial Study ◽  
Pfam Family ◽  
Swarming Motility ◽  
Sensing Systems ◽  
Family Protein ◽  
Pyocyanin Production

ABSTRACT Bacterial pathogenicity is often manifested by the expression of various cell-associated and secreted virulence factors, such as exoenzymes, protease, and toxins. In Pseudomonas aeruginosa, the expression of virulence genes is coordinately controlled by the global regulatory quorum-sensing systems, which includes the las and rhl systems as well as the Pseudomonas quinolone signal (PQS) system. Phenazine compounds are among the virulence factors under the control of both the rhl and PQS systems. In this study, regulation of the phzA1B1C1D1E1 (phzA1) operon, which is involved in phenazine synthesis, was investigated. In an initial study of inducing conditions, we observed that phzA1 was induced by subinhibitory concentrations of tetracycline. Screening of 13,000 mutants revealed 32 genes that altered phzA1 expression in the presence of subinhibitory tetracycline concentrations. Among them, the gene PA0964, designated pmpR ( p qsR-mediated P QS r egulator), has been identified as a novel regulator of the PQS system. It belongs to a large group of widespread conserved hypothetical proteins with unknown function, the YebC protein family (Pfam family DUF28). It negatively regulates the quorum-sensing response regulator pqsR of the PQS system by binding at its promoter region. Alongside phzA1 expression and phenazine and pyocyanin production, a set of virulence factors genes controlled by both rhl and the PQS were shown to be modulated by PmpR. Swarming motility and biofilm formation were also significantly affected. The results added another layer of regulation in the rather complex quorum-sensing systems in P. aeruginosa and demonstrated a clear functional clue for the YebC family proteins.

Possible antivirulent activity of some agents against clinical isolates of Pseudomonas aeruginosa

2021 ◽  
Vol 30 (2) ◽  
pp. 1-8
Author(s):  
Ahmad O. Rifai ◽  
Abeer M. Abd El-Aziz ◽  
Hany I. Kenawy
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Therapeutic Target ◽  
Inhibitory Action ◽  
Antibacterial Agents ◽  
Mechanisms Of Resistance ◽  
Life Threatening ◽  
Pheniramine Maleate ◽  
Pyocyanin Production

Background: Pseudomonas aeruginosa has developed different mechanisms of resistance against antibiotics and became one of the most life-threatening pathogens. Fighting against its virulence Factors are an alternative therapeutic target. Objective: This study was directed towards the investigation of anti-quorum sensing activity and inhibitory action on virulence factors of different agents including antibacterial agents to which Pseudomonas aeruginosa isolates are resistant and non-antibacterial agents. Methodology: Anti-quorum sensing activity of ceftriaxone, ceftazidime (CAZ), cefepime (FEP), vancomycin (VA), paracetamol (PA), and pheniramine maleate (PHE) investigated as well as their ability to reduce other virulence factors including protease, hemolysin, and pyocyanin production. Results: This study showed that 3rd and 4th generations cephalosporins could be used as anti-quorum sensing agents effectively in the treatment of Pseudomonas aeruginosa infections, however, vancomycin, paracetamol, and pheniramine maleate had no effect on inhibiting the studied virulence factors. Conclusion: From our study we conclude that although cephalosporins at the used concentrations did not show anti-pseudomonal activity they were effective as anti virulent agents that could be utilized in therapeutically in controlling Pseudomonas aeruginosa infections.

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