Production Of Virulence Factors Research Articles

Insights into Women's health: Exploring the vaginal microbiome, quorum sensing dynamics, and therapeutic potential of quorum sensing quenchers

The vaginal microbiome is an important aspect of women's health that changes dynamically with various stages of the woman's life. Just like the gut microbiome, the vaginal microbiome can also be affected by pathologies that dramatically change the typical composition of native vaginal microorganisms. However, the mechanism as to how both vaginal endemic and gut endemic opportunistic microbes can express pathogenicity in vaginal polymicrobial biofilms is poorly understood. Quorum sensing is the cellular density-dependent bacterial and fungal communication process in which chemical signaling molecules, known as autoinducers, activate expression for genes responsible for virulence and pathogenicity, such as biofilm formation and virulence factor production. Quorum sensing inhibition, or quorum quenching, has been explored as a potential therapeutic route for both bacterial and fungal infections. By applying these quorum quenchers, one can reduce biofilm formation of opportunistic vaginal microbes and combine them with antibiotics for a synergistic effect. This review aims to display the relationship between the vaginal and gut microbiome, the role of quorum sensing in polymicrobial biofilm formation which cause pathology in the vaginal microbiome, and how quorum quenchers can be utilized to attenuate the severity of bacterial and fungal infections.

Advancing Antibiotic-Resistant Microbe Combat: Nanocarrier-Based Systems in Combination Therapy Targeting Quorum Sensing

The increase in antibiotic-resistant bacteria presents a significant risk to worldwide public health, emphasizing the necessity of novel approaches to address infections. Quorum sensing, an essential method of communication among bacteria, controls activities like the formation of biofilms, the production of virulence factors, and the synthesis of secondary metabolites according to the number of individuals in the population. Quorum quenching, which interferes with these processes, emerges as a vital approach to diminish bacterial virulence and prevent biofilm formation. Nanocarriers, characterized by their small size, high surface-area-to-volume ratio, and modifiable surface chemistry, offer a versatile platform for the disruption of bacterial communication by targeting various stages within the quorum sensing pathway. These features allow nanocarriers to infiltrate biofilms, disrupt cell membranes, and inhibit bacterial proliferation, presenting a promising alternative to traditional antibiotics. Integrating nanocarrier-based systems into combination therapies provides a multi-pronged approach to infection control, enhancing both the efficacy and specificity of treatment regimens. Nonetheless, challenges related to the stability, safety, and clinical effectiveness of nanomaterial-based antimicrobial treatments remain. Continued research and development are essential to overcoming these obstacles and fully harnessing the potential of nano-antimicrobial therapies. This review emphasizes the importance of quorum sensing in bacterial behavior and highlights the transformative potential of nanotechnology in advancing antimicrobial treatments, offering innovative solutions to combat antibiotic-resistant pathogens.

Regulation of TCA cycle genes by srbA sRNA: Impacts on Pseudomonas aeruginosa virulence and survival

Pseudomonas aeruginosa, an opportunistic bacterial pathogen of public health concern, is known for its metabolic versatility, adaptability in harsh environment, and pathogenic aggressiveness. P. aeruginosa relies on various regulatory networks modulated by small non-coding RNAs, which in turn influence different physiological traits such as metabolism, stress response, and pathogenesis. In this study, srbA sRNA has been shown to play a diverse role in regulating cellular metabolism and the production of different virulence factors in P. aeruginosa. srbA was found to control the TCA cycle, a key regulatory pathway for cellular metabolism and energy production, by regulating three main enzymes: citrate synthase (gltA), isocitrate dehydrogenase (icd), and α-ketoglutarate dehydrogenase E1 subunit (sucA) at both the transcriptional and translational levels. By modulating the TCA cycle, srbA could help the bacteria to adapt nutritional stress by lowering energy consumption. Additionally, srbA has been found to differentially regulate production of various virulence factors such as rhamnolipid, elastase, LasA protease, and pyocyanin under both nutrient-rich and nutrient-limiting conditions. It could also influence motilities in P. aeruginosa, linked to biofilm formation and pathogenicity. Thus, srbA might hold a promise in the research area for identifying virulence pathways and developing novel therapeutic targets to combat the global pathogenic threat of P. aeruginosa.

Attenuation of Quorum Sensing Mediated Virulence Factors and Biofilm Formation in Pseudomonas Aeruginosa PAO1 by Substituted Chalcones and Flavonols.

Flavonoids epitomize structural scaffolds in many biologically active synthetic and natural compounds. They showcase a diverse spectrum of biological activities including anticancer, antidiabetic, antituberculosis, antimalarial, and antibiofilm activities. The antibiofilm activity of a series of new chalcones and flavonols against clinically significant Pseudomonas aeruginosa PAO1 strain was studied. Antivirulence activities were screened by analysing the effect of compounds on the production of virulence factors like pyocyanin, LasA protease, cell surface hydrophobicity, and rhamnolipid. The best ligands towards the quorum sensing proteins LasR, RhlR, and PqsR were recognised using a molecular docking study. The gene expression in P. aeruginosa after treatment with test compounds was evaluated on quorum sensing genes including rhlA, lasB, and pqsE. The antibiofilm potential of chalcones and flavonols was confirmed by the efficient reduction in the production of virulence factors and downregulation of gene expression.

Cilostazol is a promising anti-pseudomonal virulence drug by disruption of quorum sensing

Resistance to antibiotics is a critical growing public health problem that desires urgent action to combat. To avoid the stress on bacterial growth that evokes the resistance development, anti-virulence agents can be an attractive strategy as they do not target bacterial growth. Quorum sensing (QS) systems play main roles in controlling the production of diverse virulence factors and biofilm formation in bacteria. Thus, interfering with QS systems could result in mitigation of the bacterial virulence. Cilostazol is an antiplatelet and a vasodilator FDA approved drug. This study aimed to evaluate the anti-virulence activities of cilostazol in the light of its possible interference with QS systems in Pseudomonas aeruginosa. Additionally, the study examines cilostazol’s impact on the bacterium’s ability to induce infection in vivo, using sub-inhibitory concentrations to minimize the risk of resistance development. In this context, the biofilm formation, the production of virulence factors and influence on the in vivo ability to induce infection were assessed in the presence of cilostazol at sub-inhibitory concentration. Furthermore, the outcome of combination with antibiotics was evaluated. Cilostazol interfered with biofilm formation in P. aeruginosa. Moreover, swarming motility, biofilm formation and production of virulence factors were significantly diminished. Histopathological investigation revealed that liver, spleen and kidney tissues damage was abolished in mice injected with cilostazol-treated bacteria. Cilostazol exhibited a synergistic outcome when used in combination with antibiotics. At the molecular level, cilostazol downregulated the QS genes and showed considerable affinity to QS receptors. In conclusion, Cilostazol could be used as adjunct therapy with antibiotics for treating Pseudomonal infections. This research highlights cilostazol’s potential to combat bacterial infections by targeting virulence mechanisms, reducing the risk of antibiotic resistance, and enhancing treatment efficacy against P. aeruginosa. These findings open avenues for repurposing existing drugs, offering new, safer, and more effective infection control strategies.

Se-functionalized ZIF-8 nanoparticles: synthesis, characterization and disruption of biofilms and quorum sensing in Serratia marcescens

The majority of research on nanomaterials has been concentrated on metal nanoparticles since they are easily made and manipulated. Nanomaterials have shown a wide range of applications in biology. Nevertheless, their bioactivity declines due to their extreme susceptibility to and novel Se@ZIF-8 by chemical method. The sizes and morphologies of Se (0) and Se@ZIFchemical and physical stimuli. The goal of encapsulating these nanomaterials in a matrix is gradually being pursued, which boosts their affordability, stability, and usability. Metal-organic frameworks, often known as MOFs, have the potential to be the best platforms for encapsulating metal nanoparticles due to their well-defined frameworks, persistent porosity, and flexibility in modification. In this investigation, we report the synthesis and optimization of polyvinylpyrrolidone-stabilized Se(0) nanoparticles -8 were affected by the ratios of Se/Zn2+and [hmim]/Zn2+used. The optimized Se@ZIF-8 nanoparticles exhibited a particle size and zeta potential of 319 nm and -34 mv respectively. Transmission electron microscopy displayed spherical morphology for Se(0) nanoparticles, whereas the surface morphology of novel Se@ZIF-8 nanoparticles was drastically changed to hexagonal shaped structures with smooth surface morphologies in scanning electron microscopy (SEM). The DTA, TG/DTG, XRD analysis confirmed the presence of novel Se incorporated ZIF-8 nanoparticulate framework. The synthesized novel Se@ZIF-8 nanoparticles showed efficient antibacterial activity as evidenced by low MIC values. Interestingly, these Se@ZIF-8 NPs not only inhibited biofilm formation inS. marcescens,but also effectively eradicated mature biofilms by degrading the eDNA of the EPS layer. It was validated by confocal laser scanning microscopy and SEM analysis. It was observed that Se@ZIF-8 targeted the Quroum Sensing pathway and reduced its associated virulence factors production. This work opens up a different approach of Se@ZIF-8 nanoparticles as novel antibiotics to treat biofilm-associated infections caused byS. marcescensand offer a solution for antimicrobial resistance.

Influence of carbonyl cyanide m-chlorophenyl hydrazone on biofilm dynamics, protease, and siderophore production by Burkholderia pseudomallei

Efflux pump inhibitors are a potential therapeutic strategy for managing antimicrobial resistance and biofilm formation. This article evaluated the effect of carbonyl cyanide m-chlorophenyl hydrazone (CCCP) on the biofilm growth dynamics and the production of virulence factors by Burkholderia pseudomallei. The effects of CCCP on planktonic, growing, and mature biofilm, interaction with antibacterial drugs, and protease and siderophore production were assessed. CCCP MICs ranged between 128 and 256 µM. The CCCP (128 µM) had a synergic effect with all the antibiotics tested against biofilms. Additionally, CCCP reduced (p < .05) the biomass of biofilm growth and mature biofilms at 128 and 512 µM, respectively. CCCP also decreased (p < .05) protease production by growing (128 µM) and induced (p < .05) siderophore release by planktonic cells (128 µM) growing biofilms (12.8 and 128 µM) and mature biofilms (512 µM). CCCP demonstrates potential as a therapeutic adjuvant for disassembling B. pseudomallei biofilms and enhancing drug penetration.

New arsenals for old armour: Biogenic nanoparticles in the battle against drug-resistant Candidaalbicans

Candida albicans is a common commensal fungus and fourth most frequent causative agent of nosocomial infections including life-threatening invasive candidiasis in humans. The effectiveness of present antifungal therapies using azoles, polyenes, flucytosine and echinocandins has plateaued in managing fungal infections. The limitations of these antifungal drugs are related to polymorphic morphology, biofilm formation, emergence of drug-resistant strains and production of several virulence factors. Development of new antifungal agents, which can particularly afflict multiple cellular targets and limiting evolving resistant strains are needed. Recently, metal nanoparticles have emerged as a source of new antifungal agents for antifungal formulations. Furthermore, green nanotechnology deals with the use of biosynthetic routes that offer new avenue for synthesizing antifungal nanoparticles coupled with less toxic chemical inventory and environmental sustainability. This article reviews the recent developments on C. albicans pathogenesis, biofilm formation, drug resistance, mode of action of antifungal drugs and antifungal activities of metal nanoparticles. The antifungal efficacy and mode of action of metal nanoparticles are described in the context of prospective therapeutic applications.

A microbiological survey approach to understanding the virulence factors of Pseudomonas species in healthcare sinks

Hospital water is involved in both the prevention and spread of healthcare associated infections (HCAI). Handwashing is key to reducing the transmission of pathogens, yet numerous outbreaks have been found to be caused by organisms within sinks, taps, and showers. Pseudomonas aeruginosa and increasingly non-aeruginosa Pseudomonas cause waterborne HCAI, however, little is known about the virulence potential of Pseudomonas species found within hospital environments. Swabs were taken from 62 sinks within two newly opened wards at Great Ormond Street Hospital, samples were taken before and after the wards opened to understand the impact of patient occupancy on sink microorganisms. Culturable bacteria were identified by MALDI-TOF and virulence factors assessed through phenotypic methods. A total of 106 bacterial isolates were recovered including 24 Pseudomonas isolates. Of these 25% were identified as P. oleovorans, 21% P. aeruginosa, 17% P. composti, 13% P. alicalipha, 8% P. monteilli, 4% P. putida, 4% P. stutzeri, and 8% could only be identified to genus level by MALDI-TOF. Differences were seen in both the number of Pseudomonas isolates and virulence production between the two wards, overall 25% of the Pseudomonas isolates produced pigment, 58% were capable of haemolysis, 87.5% were able to swim, 83.3% were capable of twitching motility, 33.3% produced alkaline protease, and 8.3% produced gelatinase. Results suggest that patients may be back contaminating sinks with colonising organisms which has ongoing implications for infection prevention and control. Additionally, this work highlights the ability of non-aeruginosa Pseudomonas to produce virulence factors traditionally associated with P. aeruginosa.

Exploring rose absolute and phenylethyl alcohol as novel quorum sensing inhibitors in Pseudomonas aeruginosa and Chromobacterium violaceum

Inter-cellular signaling, referred to as quorum sensing (QS), regulates the production of virulence factors in numerous gram-negative bacteria, such as the human pathogens Pseudomonas aeruginosa and Chromobacterium violaceum. QS inhibition may provide an opportunity for the treatment of bacterial infections. This represents the initial study to examine the antibiofilm and antivirulence capabilities of rose absolute and its primary component, phenylethyl alcohol. QS inhibition was assessed by examining extracellular exopolysaccharide synthesis, biofilm development, and swarming motility in P. aeruginosa PAO1, along with violacein production in C. violaceum ATCC 12472. Molecular docking analysis was conducted to explore the mechanism by which PEA inhibits QS. Our results indicate that rose absolute and PEA caused decrease in EPS production (60.5–33.5%), swarming motility (94.7–64.5%), and biofilm formation (98.53–55.5%) in the human pathogen P. aeruginosa PAO1. Violacein production decreased by 98.1% and 62.5% with an absolute (0.5 v/v %) and PEA (2 mM). Moreover, the molecular docking analysis revealed a promising competitive interaction between PEA and AHLs. Consequently, this study offers valuable insights into the potential of rose absolute and PEA as inhibitors of QS in P. aeruginosa and C. violaceum.

ABC genotyping, virulence factors production and antifungal resistant pattern of Candida albicans isolated from immunocompromised patients with candidemia

ABC genotyping, virulence factors production and antifungal resistant pattern of Candida albicans isolated from immunocompromised patients with candidemia

Growth on Douglas fir media facilitates Cryptococcus virulence factor production and enhances fungal survival against environmental and immune stressors.

The yeasts Cryptococcus neoformans and Cryptococcus gattii are fungal pathogens that can be isolated from the environment, including the surfaces of many plants. Cryptococcus gattii caused an outbreak on Vancouver Island, British Columbia beginning in 1999 that has since spread to the Pacific Northwest of the United States. Coastal Douglas fir (Pseudotsuga menziesii) is an important lumber species and a major component of the ecosystems in this area. Previous research has explored Cryptococcus survival and mating on Douglas fir plants and plant-derived material, but no studies have been done on the production of cryptococcal virulence factors by cells grown on those media. Here, we investigated the effects of growth on Douglas fir-derived media on the production of the polysaccharide capsule and melanin, two of the most important cryptococcal virulence factors. We found that while the capsule was mostly unchanged by growth in Douglas fir media compared to cells grown in defined minimal media, Cryptococcus spp. can use substrates present in Douglas fir to synthesize functional and protective melanin. These results suggest mechanisms by which Cryptococcus species may survive in the environment and emphasize the need to explore how association with Douglas fir trees could affect its epidemiology for human cryptococcosis.

1H-Pyrrole-2,5-dicarboxylic acid, a quorum sensing inhibitor from one endophytic fungus in Areca catechu L., acts as antibiotic accelerant against Pseudomonas aeruginosa.

Pseudomonas aeruginosa has already been stipulated as a "critical" pathogen, emphasizing the urgent need for researching and developing novel antibacterial agents due to multidrug resistance. Bacterial biofilm formation facilitates cystic fibrosis development and restricts the antibacterial potential of many current antibiotics. The capacity of P. aeruginosa to form biofilms and resist antibiotics is closely correlated with quorum sensing (QS). Bacterial QS is being contemplated as a promising target for developing novel antibacterial agents. QS inhibitors are a promising strategy for treating chronic infections. This study reported that the active compound PT22 (1H-pyrrole-2,5-dicarboxylic acid) isolated from Perenniporia tephropora FF2, one endophytic fungus from Areca catechu L., presents QS inhibitory activity against P. aeruginosa. Combined with gentamycin or piperacillin, PT22 functions as a novel antibiotic accelerant against P. aeruginosa. PT22 (0.50 mg/mL, 0.75 mg/mL, and 1.00 mg/mL) reduces the production of QS-related virulence factors, such as pyocyanin and rhamnolipid, and inhibits biofilm formation of P. aeruginosa PAO1 instead of affecting its growth. The architectural disruption of the biofilms was confirmed by visualization through scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Real-time quantitative PCR (RT-qPCR) indicated that PT22 significantly attenuated the expression of QS-related genes followed by docking analysis of molecules against QS activator proteins. PT22 dramatically increased the survival rate of Galleria mellonella. PT22 combined with gentamycin or piperacillin presents significant inhibition of biofilm formation and eradication of mature biofilm compared to monotherapy, which was also confirmed by visualization through SEM and CLSM. After being treated with PT22 combined with gentamycin or piperacillin, the survival rates of G. mellonella were significantly increased compared to those of monotherapy. PT22 significantly enhanced the susceptibility of gentamycin and piperacillin against P. aeruginosa PAO1. Our results suggest that PT22 from P. tephropora FF2 as a potent QS inhibitor is a candidate antibiotic accelerant to combat the antibiotic resistance of P. aeruginosa.

Dopamine, an exogenous quorum sensing signaling molecule or a modulating factor in Pseudomonas aeruginosa?

Pseudomonas aeruginosa is recognized globally as an opportunistic pathogen of considerable concern due to its high virulence and pathogenicity, especially in immunocompromised individuals. While research has identified several endogenous quorum sensing (QS) signaling molecules that enhance the virulence and pathogenicity of P. aeruginosa, investigations on exogenous QS signaling molecules or modulating factors remain limited. This study found that dopamine serves as an exogenous QS signaling molecule or modulating factor of P. aeruginosa PAO1, enhancing the production of virulence factors and biofilms. Compared to the control group, treatment with 40 μM dopamine resulted in a 33.1 % increase in biofilm formation, 68.1 % increase in swimming mobility, 63.1 % increase in swarming mobility, 147.2 % increase in the signaling molecule 3-oxo-C12-HSL, and 50.5 %, 28.5 %, 27.0 %, and 33.2 % increases in the virulence factors alginate, rhamnolipids, protease, and pyocyanin, respectively. This study further explored the mechanism of dopamine regulating the biofilm formation and virulence of P. aeruginosa PAO1 through transcriptome and metabolome. Transcriptomic analysis showed that dopamine promoted the expression of virulence genes psl, alg, lasA, rhlABC, rml, and phz in P. aeruginosa PAO1. Metabolomic analysis revealed changes in the concentrations of tryptophan, pyruvate, ethanolamine, glycine, 3-hydroxybutyric acid, and alizarin. Furthermore, KEGG enrichment analysis of altered genes and metabolites indicated that dopamine enhanced phenylalanine, tyrosine, and tryptophan in P. aeruginosa PAO1. The results of this study will contribute to the development of novel exogenous QS signaling molecules or modulating factors and advance our understanding of the interactions between P. aeruginosa and the host environment.

Characterization of Aspergillus fumigatus secretome during sublethal infection of Galleria mellonella larvae.

Introduction. The fungal pathogen Aspergillus fumigatus can induce prolonged colonization of the lungs of susceptible patients, resulting in conditions such as allergic bronchopulmonary aspergillosis and chronic pulmonary aspergillosis.Hypothesis. Analysis of the A. fumigatus secretome released during sub-lethal infection of G. mellonella larvae may give an insight into products released during prolonged human colonisation.Methodology. Galleria mellonella larvae were infected with A. fumigatus, and the metabolism of host carbohydrate and proteins and production of fungal virulence factors were analysed. Label-free qualitative proteomic analysis was performed to identify fungal proteins in larvae at 96 hours post-infection and also to identify changes in the Galleria proteome as a result of infection.Results. Infected larvae demonstrated increasing concentrations of gliotoxin and siderophore and displayed reduced amounts of haemolymph carbohydrate and protein. Fungal proteins (399) were detected by qualitative proteomic analysis in cell-free haemolymph at 96 hours and could be categorized into seven groups, including virulence (n = 25), stress response (n = 34), DNA repair and replication (n = 39), translation (n = 22), metabolism (n = 42), released intracellular (n = 28) and cellular development and cell cycle (n = 53). Analysis of the Gallerial proteome at 96 hours post-infection revealed changes in the abundance of proteins associated with immune function, metabolism, cellular structure, insect development, transcription/translation and detoxification.Conclusion. Characterizing the impact of the fungal secretome on the host may provide an insight into how A. fumigatus damages tissue and suppresses the immune response during long-term pulmonary colonization.

Antibiofilm activity of Prevotella species from the cystic fibrosis lung microbiota against Pseudomonas aeruginosa

It is increasingly recognized that interspecies interactions may modulate the pathogenicity of Pseudomonas aeruginosa during chronic lung infections. Nevertheless, while the interaction between P. aeruginosa and pathogenic microorganisms co-infecting the lungs has been widely investigated, little is known about the influence of other members of the lung microbiota on the infection process. In this study, we focused on investigating the impact of Prevotella species isolated from the sputum of people with cystic fibrosis (pwCF) on biofilm formation and virulence factor production by P. aeruginosa. Screening of a representative collection of Prevotella species recovered from clinical samples showed that several members of this genus (8 out 10 isolates) were able to significantly reduce biofilm formation of P. aeruginosa PAO1, without impact on growth. Among the tested isolates, the strongest biofilm-inhibitory activity was observed for Prevotella intermedia and Prevotella nigrescens, which caused a reduction of up to 90% in the total biofilm biomass of several P. aeruginosa isolates from pwCF. In addition, a strain-specific effect of P. nigrescens on the ability of P. aeruginosa to produce proteases and pyocyanin was observed, with significant alterations in the levels of these virulence factors detected in LasR mutant strains. Overall, these results suggest that non-pathogenic bacteria from the lung microbiota may regulate pathogenicity traits of P. aeruginosa, and possibly affect the outcome of chronic lung infections.

Dencichine attenuates the virulence of Fusobacterium nucleatum by targeting hydrogen sulfide-producing enzyme.

Oral opportunistic pathogen Fusobacterium nucleatum can participate in various disease processes through the metabolite hydrogen sulfide, such as halitosis and colorectal cancer. The object of this study is to identify inhibitor capable of suppressing Fn1220, which is the principal hydrogen sulfide-producing enzyme in F. nucleatum. Through this inhibition, we aim to reduce the hydrogen sulfide production of F. nucleatum, consequently diminishing its virulence. Employing molecular docking techniques for inhibitor screening, we identified dencichine as the monomeric compound from Chinese medicine exhibiting the lowest binding energy to Fn1220 among a set of 27,045 candidates, and evaluated in vitro the ability of dencichine to inhibit hydrogen sulfide production using bismuth chloride method. Additionally, we investigated its impact on key virulence factors, including biofilm formation, hemolysis, and adhesion factors of F. nucleatum, using the crystalline violet method, sheep blood method, and RT-qPCR, respectively. Furthermore, we assessed the influence of dencichine on the lifespan of Caenorhabditis elegans. Results showed that dencichine was a suitable inhibitor of the Fn1220 of F. nucleatum, which significantly inhibited the production of virulence factors, e.g., biofilm, hemolysin, FadA, and Fap2 of F. nucleatum and improved the survival of C. elegans. We successfully identified the inhibitor of the enzyme Fn1220, dencichine, which inhibited the production of hydrogen sulfide and attenuated the virulence of F. nucleatum and holds promise as a potential therapeutic avenue for addressing oral diseases, e.g., halitosis in the future.

Investigating Sulforaphane's anti-virulence and anti-quorum sensing properties against Pseudomonas aeruginosa.

P. aeruginosa, a significant bacterium, can cause severe illness and resistance to antibiotics. Quorum sensing (QS) systems regulate virulence factors production. Targeting QS could reduce bacteria pathogenicity and prevent antibiotic resistance. Cruciferous vegetables contain sulforaphane, known for its anti-inflammatory, antioxidant, anticancer, and antimicrobial properties. We aimed to examine the inhibitory influences of sulforaphane, at a sub-inhibitory concentration (¼ minimum inhibitory concentration, MIC), on virulence and QS in P. aeruginosa. The sulforaphane's anti-virulence actions at sub-inhibitory concentrations were explored in vitro and in vivo. A sub-MIC concentration of sulforaphane was combined with anti-pseudomonal drugs, and the results of this combination were assessed. The virtual affinity of sulforaphane for the receptors of QS was studied, and its effect on the expression of QS genes was quantified. Sulforaphane significantly decreased the biofilm formation, motility, ability to withstand oxidative stress, and the synthesis of virulence extracellular enzymes such as proteases, hemolysins, and elastase, as well as other virulence factors like pyocyanin. In addition, sulforaphane lessened the severity of P. aeruginosa infection in mice. Sulforaphane reduced the antipseudomonal antibiotics' MICs when used together, resulting in synergistic effects. The observed anti-virulence impacts were attributed to the ability of sulforaphane to inhibit QS via suppressing the QS genes' expression. Sulforaphane shows promise as a potent anti-virulence and anti-QS agent that can be used alongside conventional antimicrobials to manage severe infections effectively. Furthermore, this study paves the way for further investigation of sulforaphane and similar structures as pharmacophores for anti-QS candidates.

Veratryl Alcohol Attenuates the Virulence and Pathogenicity of Pseudomonas aeruginosa Mainly via Targeting las Quorum-Sensing System.

Pseudomonas aeruginosa is an opportunistic pathogen that usually causes chronic infections and even death in patients. The treatment of P. aeruginosa infection has become more challenging due to the prevalence of antibiotic resistance and the slow pace of new antibiotic development. Therefore, it is essential to explore non-antibiotic methods. A new strategy involves screening for drugs that target the quorum-sensing (QS) system. The QS system regulates the infection and drug resistance in P. aeruginosa. In this study, veratryl alcohol (VA) was found as an effective QS inhibitor (QSI). It effectively suppressed the expression of QS-related genes and the subsequent production of virulence factors under the control of QS including elastase, protease, pyocyanin and rhamnolipid at sub-inhibitory concentrations. In addition, motility activity and biofilm formation, which were correlated with the infection of P. aeruginosa, were also suppressed by VA. In vivo experiments demonstrated that VA could weaken the pathogenicity of P. aeruginosa in Chinese cabbage, Drosophila melanogaster, and Caenorhabditis elegans infection models. Molecular docking, combined with QS quintuple mutant infection analysis, identified that the mechanism of VA could target the LasR protein of the las system mainly. Moreover, VA increased the susceptibility of P. aeruginosa to conventional antibiotics of tobramycin, kanamycin and gentamicin. The results firstly demonstrate that VA is a promising QSI to treat infections caused by P. aeruginosa.

Molecular insights into flavone-mediated quorum sensing interference: A novel strategy against Serratiamarcescens biofilm-induced antibiotic resistance"

Antibiotic resistance poses a significant challenge in modern medicine, urging the exploration of innovative approaches to combat bacterial infections. Biofilms, complex bacterial communities encased in a protective matrix, contribute to resistance by impeding antibiotic efficacy and promoting genetic exchange. Understanding biofilm dynamics is crucial for developing effective antimicrobial therapies against antibiotic resistance. This study explores the potential of flavone to combat biofilm-induced antibiotic resistance by employing in-vitro biochemical, cell biology, and Insilico (MD simulation), approaches. Flavone exhibited potent antibacterial effects with a low minimum inhibitory concentration by inducing intracellular reactive oxygen species. Flavones further inhibited the formation of biofilms by 50–60 % and disrupted the pre-formed biofilms by reducing the extracellular polysaccharide substance protective layer formed on the biofilm by 80 %. Quorum sensing (QS) plays a crucial role in bacterial pathogenicity and flavone significantly attenuated the production of QS-induced virulence factors like urease, protease, lipase, hemolysin and prodigiosin pigment in a dose-dependent manner. Further Insilico molecular docking studies along with molecular dynamic simulations run for 100 ns proved the stable binding affinity of flavone with QS-specific proteins which are crucial for biofilm formation. This study demonstrates the therapeutic potential of flavone to target QS-signaling pathway to combat S.marcescens biofilms.