Biofilm inhibition/eradication: exploring strategies and confronting challenges in combatting biofilm.

Biofilms are complex communities of microorganisms enclosed in a self-produced extracellular matrix, posing a significant threat to different sectors, including healthcare and industry. This review provides an overview of the challenges faced due to biofilm formation and different novel strategies that can combat biofilm formation. Bacteria inside the biofilm exhibit increased resistance against different antimicrobial agents, including conventional antibiotics, which can lead to severe problems in livestock and animals, including humans. In addition, biofilm formation also imposes heavy economic pressure on industries. Hence it becomes necessary to explore newer alternatives to eradicate biofilms effectively without applying selection pressure on the bacteria. Excessive usage of antibiotics may also lead to an increase in the number of resistant strains as bacteria employ an advanced antimicrobial resistance mechanism. This review provides insight into multifaceted technologies like quorum sensing inhibition, enzymes, antimicrobial peptides, bacteriophage, phytocompounds, and nanotechnology to neutralize biofilms without developing antimicrobial resistance (AMR). Furthermore, it will pave the way for developing newer therapeutic agents to deal with biofilms more efficiently.

Pseudomonas aeruginosa quorum-sensing molecule N-(3-oxododecanoyl)-L-homoserine lactone mediates Ca+2 dysregulation, mitochondrial dysfunction, and apoptosis in human peripheral blood lymphocytes.

N-(3-oxododecanoyl)-l-homoserine lactone is a Pseudomonas aeruginosa secreted quorum-sensing molecule that mediates the secretion of virulence factors, biofilm formation and plays a pivotal role in proliferation and persistence in the host. Apart from regulating quorum-sensing, the autoinducer signal molecule N-(3-oxododecanoyl)-l-homoserine lactone (3O-C12-HSL or C12) of a LasI-LasR circuit exhibits immunomodulatory effects and induces apoptosis in various host cells. However, the precise pathophysiological impact of C12 on human peripheral blood lymphocytes and its involvement in mitochondrial dysfunction remained largely elusive. In this study, the results suggest that C12 (100 µM) induces upregulation of cytosolic and mitochondrial Ca+2 levels and triggers mitochondrial dysfunction through the generation of mitochondrial ROS (mROS), disruption of mitochondrial transmembrane potential (ΔΨm), and opening of the mitochondrial permeability transition pore (mPTP). Additionally, it was observed that C12 induces phosphatidylserine (PS) exposure and promotes apoptosis in human peripheral blood lymphocytes. However, apoptosis plays a critical role in the homeostasis and development of lymphocytes, whereas enhanced apoptosis can cause immunodeficiency through cell loss. These findings suggest that C12 exerts a detrimental effect on lymphocytes by mediating mitochondrial dysfunction and enhancing apoptosis, which might further impair the effective mounting of immune responses during Pseudomonas aeruginosa-associated infections.

Data regarding anti-quorum sensing and antimicrobial activity of Melaleuca alternifolia and Salvia sclarea essential oil against Pseudomonas aeruginosa.

To combat the increasing number of multi-drug resistant bacteria, researchers are now looking for alternatives that reduce the virulence and pathogenic potential of the bacteria without killing it. It can be accomplished by interfering with the quorum sensing (QS) system of bacteria. In this article, we aim to determine the antimicrobial and anti-QS activity of Salvia sclarea and Melaleuca alternifolia essential oils (EOs) against Pseudomonas aeruginosa. The sub-lethal concentration of these EOs was found with the help of a growth curve, and further experiments were carried out below this concentration. To check for their anti-quorum activity, a bioreporter strain E. coli pJN105LpSC11 (to measure the concentration of 3-oxo-C12-HSL) and Chromobacterium violaceum CV026 (to check for the reduction in the formation of violacein pigment) was used. Several virulence phenotype assays like pyocyanin, alginate, and protease production, along with swarming motility, were done. The effect of these EOs on biofilm formation was also checked. The results were confirmed by checking the expression of genes by real-time PCR.

An in vivo acute toxicity and anti-shigellosis effect of designed formulation on rat.

INTRODUCTION: Shigellosis is an intestinal disease and is one of the main causes of morbidity and mortality among children in India. The study aims to analyze the effect of the designed formulation on the hematological parameters in shigellosis-induced rats and assess the in vivo toxicity of this formulation. METHODS: Male Wistar rats were housed in different groups. Group 1 is normal control; group 2 is diseased control; group 3 and group 4 diseased rats received 250 mg/kg formulation and 20 mg/kg body weight norfloxacin, respectively, orally once a day. Shigellosis was induced by a single intraperitoneal injection of Shigella flexneri, and bacterial load was calculated using the Shigella agar plate. On completion of the study, blood was collected for hematological as well as electrolyte analysis. RESULTS: The in vivo acute toxicity results indicate that the formulation is safe up to 2000 mg/kg. Furthermore, formulation significantly (p < 0.05) decreases the bacterial load and increases the RBC, WBC, MCHC, platelet, hemoglobin, and electrolytes (Ca++, K+, and Na+) compared to diseased control. CONCLUSION: The results support the designed formulation's safety and therapeutic effects and support its use as an alternative medicine for treating shigellosis.

Pseudomonas quinolone signal induces organelle stress and dysregulates inflammation in human macrophages.

Pseudomonas quinolone signal (PQS) is a quorum-sensing molecule associated with Pseudomonas aeruginosa that regulates quorum sensing, extracellular vesicle biogenesis, iron acquisition, and the secretion of virulence factors. PQS has been shown to have immunomodulatory effects on the host. It induces oxidative stress, modulates cytokine levels, and activates regulated cell death in the host. In this study, we investigated the effects of PQS (10 µM) on host organelle dynamics and dysfunction in human macrophages at the interphase of endoplasmic reticulum (ER), mitochondria, and lysosome. This study showed that PQS increases cytosolic Ca+2 levels and elevates ER stress, as evidenced by increased expression of BiP and activation of the PERK-CHOP axis of unfolded protein response (UPR). Moreover, PQS also negatively affects mitochondria by disrupting mitochondrial membrane potential and increasing mitochondrial ROS generation (mROS). Additionally, PQS stimulation decreased the number of acridine orange-positive lysosomes, indicating lysosomal destabilization. Furthermore, PQS-induced lysosomal destabilization also induces overexpression of the lysosomal stress-responsive gene TFEB. Besides organelle dysfunction, PQS dysregulates inflammation-related genes by upregulating NLRC4, TMS1, and Caspase 1 while downregulating NLRP3 and IL-1ß. Also, PQS increases gene expression of pro-inflammatory cytokines (IL-6, TNF-α, and IFN-γ). In conclusion, our findings suggest that PQS negatively affects human macrophages by interfering with organelle function and dysregulating inflammatory response. Consequently, this study provides crucial insight into PQS-driven macrophage dysfunction and may contribute to a better understanding of Pseudomonas aeruginosa-associated infections.

Pseudomonas aeruginosa quorum-sensing molecule N-(3-oxododecanoyl) homoserine lactone induces calcium signaling-dependent crosstalk between autophagy and apoptosis in human macrophages.

N-(3-oxododecanoyl) homoserine lactone (3oc) is a Pseudomonas aeruginosa secreted quorum-sensing signal molecule playing a crucial role in regulating quorum-sensing (QS) dependent biofilm formation and secretion of virulence factors. In addition to regulating quorum sensing, 3oc also plays an immunomodulatory role in the host by triggering regulated cell death in immune cells. The molecular mechanisms of 3oc in modulating macrophage pathologies are still unclear. In this study, we hypothesized the novel 3oc mediated crosstalk between autophagy and apoptosis at the interphase of calcium signaling in human macrophages. The study showed that 3oc induces mitochondrial dysfunction and apoptosis in macrophages through elevating cytosolic Ca+2 ([Ca+2]cyt) levels. Pre-treatment with the calcium-specific chelator BAPTA-AM effectively abrogated 3oc-induced apoptotic events, like mitochondrial ROS generation (mROS), mitochondrial membrane potential (MMP) drop, and phosphatidylserine (PS) exposure. The study also showed that 3oc induces autophagy, as assessed by the accumulation of autophagic vacuoles, induction of lysosomal biogenesis, upregulation of autophagy genes (LC3, BECLIN 1, STX17, PINK1, and TFEB), autophagosomes formation, and LC3 lipidation. Mechanistically, our study proved that 3oc-induced autophagy was [Ca+2]cyt dependent as BAPTA-AM pre-treatment reduced autophagosome formation. Furthermore, inhibiting autophagy with chloroquine attenuated 3oc-induced apoptosis, while autophagy induction with rapamycin aggravated cell death, suggesting autophagy plays a role in cell death in 3oc-treated macrophages. In conclusion, our findings indicate that 3oc activates a multifaceted death signaling by activating autophagy and apoptosis through Ca+2 signaling, and we propose pharmacological modulation of Ca+2 signaling may act as a combinatorial therapeutic intervention in patients with Pseudomonas aeruginosa-associated infections.

Evaluation of anti-biofilm, anti-quorum, anti-dysenteric potential of designed polyherbal formulation: in vitro and in vivo study.

Bacillary dysentery (shigellosis) continues to cause havoc worldwide, with a high infectivity rate. It causes bloody diarrhea, and around 99% of bacillary dysentery cases occur in developing countries. The objective of this study is to develop a polyherbal formulation with the scientific rationale in treating infectious bacillary dysentery disease. The anti-bacterial activity, the minimum inhibitory concentration of the formulation against bacillary dysentery, causing microbes like Shigella flexneri (MTCC 1457), Escherichia coli (MTCC 1687), and Salmonella enterica (MTCC 98), was analysed by well-diffusion method and broth dilution method, respectively. The biofilm inhibition activity was determined on 96 well polystyrene plates and anti-quorum sensing activity by Chromobacterium violaceum CV026. The cytotoxicity was examined by acute oral toxicity. Excreta and organ bacterial load were analyzed by serial dilution method. The formulation efficacy was determined by analyzing the blood sample of rats. The antimicrobial efficacy of the developed formulation was calculated by measuring the zone of inhibition which was found to be 24 mm, 25 mm, and 25 mm, and the MIC values of 1.5 mg/ml, 1.5 mg/ml, and 2.0 mg/ml against S. flexneri, S. enterica, E. coli, respectively. The results show that the polyherbal formulation significantly reduced biofilm formation and has anti-quorum sensing activity. The formulation also effectively decreases the bacterial load and increases the K+, Na+, and Ca++ ions in animals treated with the formulation. The developed formulation was found to be non-toxic and effective against bacillary dysentery; thus, it can be used for treating bacillary dysentery and related complications.

Screening of anti-microbial, anti-biofilm activity, and cytotoxicity analysis of a designed polyherbal formulation against shigellosis.

BACKGROUND: Shigellosis is an infectious intestinal disease common in rural communities. In developing countries, shigellosis is caused predominantly by Shigella flexneri and has been determined as a major cause of morbidity and mortality. OBJECTIVE: The study investigates the anti-biofilm, anti-microbial, and anti-shigellosis activity of a designed formulation. MATERIALS AND METHODS: The potential of the formulation against S. flexneri (MTCC 1457) was investigated using a well-diffusion assay. Further, the effect of the designed formulation on bacterial growth and biofilm formation was analyzed by the spectrophotometry method. Anti-quorum sensing activity was analyzed using Chromobacterium violaceum CV026, a bacterial strain. Finally, the cytotoxicity of the formulation was examined by using cell line and brine shrimp lethality assay. RESULTS: The MIC value of the aqueous extract of the formulation was 2.4 mg ml-1 and an inhibitory zone of 23 mm was observed. On the other side, the formulation significantly inhibited the bacterial growth, biofilm formation (23.78%), violacein inhibition (27.68%) at 0.6 mg ml-1 concentration (did not significantly affect the growth curves) and was found non-toxic in cell assay and brine shrimp lethality assay. CONCLUSION: According to the result obtained, the designed formulation was found effective and non-toxic, so it can be used to treat shigellosis and Shigella-related infections.

Evaluating the efficacy of nitazoxanide in uncomplicated amebic liver abscess.

BACKGROUND: Amebic liver abscess is treated successfully with metronidazole or another nitroimidazole drug followed by a luminal amebicide. Metronidazole has long been preferred, but has been associated with several adverse effects including intolerance in certain clinical situations. Mechanisms of metronidazole resistance and mutagenic potential have been described. Effects of the use of drug in pregnant women and infants of lactating women are unknown. Nitazoxanide was proven to be efficacious in treating invasive intestinal amebiasis. Therefore, the present study was undertaken to assess the efficacy and safety of nitazoxanide as compared to metronidazole in patients with uncomplicated amebic liver abscess. METHODS: Patients with clinical and ultrasonography features suggestive of liver abscess, positive amebic serology, and/or anchovy sauce appearance on aspiration of the pus were included in the study and randomized into two parallel treatment groups. Group M received metronidazole, 2-2.5 g/day intravenous (IV), for inpatients, or 2-2.4 g/day oral, for outpatients in three divided doses for 14 days. Group N received nitazoxanide 500 mg BD per oral for 10 days. RESULTS: A total of sixty subjects fulfilling the inclusion criteria were randomized equally into two groups, group M and group N. Number of patients achieving symptomatic clinical response (SCR) was similar in the two groups (80% vs. 76.7%, p = 1.00), though time to achieve symptomatic clinical response was significantly lower in metronidazole group as compared to that in nitazoxanide group. Greater proportion of patients achieved early clinical response (ECR) in metronidazole group as compared to nitazoxanide group. Complete resolution of abscess, at 6 months, was noted in 18 (60%) patients in the M group and 22 (73.3%) patients in the N group (p = 0.273). Metronidazole was associated with significantly greater frequency of adverse effects than nitazoxanide. CONCLUSIONS: This study shows equivalent efficacy of nitazoxanide in uncomplicated amebic liver abscess as compared to metronidazole, with better tolerability and advantage of simultaneous luminal clearance, thus reducing chances of recurrence. TRIAL REGISTRATION: CTRI/2019/01/017249.

Autoinducer N-(3-oxododecanoyl)-l-homoserine lactone induces calcium and reactive oxygen species-mediated mitochondrial damage and apoptosis in blood platelets.

Acylated homoserine lactones (AHL) such as N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C12 HSL) and N-butyryl-l-homoserine lactone (C4 HSL) are the most common autoinducer molecules in Pseudomonas aeruginosa. These AHL molecules not only regulate the expression of virulence factors but also have been shown to interfere with the host cell and modulate its functions. Recently, we reported that 3-oxo-C12 HSL but not C4 HSL causes cytosolic Ca2+ rise and ROS production in platelets. In this study, we examined the potential of AHLs to induce apoptosis in the human blood platelet. Our result showed that 3-oxo-C12 HSL but not C4 HSL causes phosphatidylserine (PS) exposure, mitochondrial dysfunction (mitochondrial transmembrane potential loss, and mitochondrial permeability transition pore (mPTP) formation). Besides, 3-oxo-C12 HSL also inhibited thrombin-induced platelet aggregation and clot retraction. The pretreatment of an intracellular calcium chelator BAPTA-AM or ROS inhibitor (DPI) significantly attenuated the 3-oxo-C12 HSL induced apoptotic characters such as PS exposure and mitochondrial dysfunctions. These data, including our previous findings, confirmed that 3-oxo-C12 HSL induced intracellular Ca2+ mediated ROS production results in the activation and subsequent induction of apoptotic features in platelets. Our results demonstrated that the 3-oxo-C12 HSL modulates the functions of platelets that may cause severe thrombotic complications in P. aeruginosa infected individuals.

Crosstalk between Platelet and Bacteria: A Therapeutic Prospect.

Platelets are typically recognized for their roles in the maintenance of hemostasis and vascular wall repair to reduce blood loss. Beyond hemostasis, platelets also play a critical role in pathophysiological conditions like atherosclerosis, stroke, thrombosis, and infections. During infection, platelets interact directly and indirectly with bacteria through a wide range of cellular and molecular mechanisms. Platelet surface receptors such as GPIbα, FcγRIIA, GPIIbIIIa, and TLRs, etc. facilitate direct interaction with bacterial cells. Besides, the indirect interaction between platelet and bacteria involves host plasma proteins such as von Willebrand Factor (vWF), fibronectin, IgG, and fibrinogen. Bacterial cells induce platelet activation, aggregation, and thrombus formation in the microvasculature. The activated platelets induce the Neutrophil Extracellular Traps (NETs) formation, which further contribute to thrombosis. Thus, platelets are extensively anticipated as vital immune modulator cells during infection, which may further lead to cardiovascular complications. In this review, we cover the interaction mechanisms between platelets and bacteria that may lead to the development of thrombotic disorders. Platelet receptors and other host molecules involved in such interactions can be used to develop new therapeutic strategies to combat against infection-induced cardiovascular complications. In addition, we highlight other receptor and enzyme targets that may further reduce infection-induced platelet activation and various pathological conditions.

Pseudomonas aeruginosa quorum-sensing molecule N-(3-oxo-dodecanoyl)-L-homoserine lactone triggers mitochondrial dysfunction and apoptosis in neutrophils through calcium signaling.

Pseudomonas aeruginosa is an opportunistic pathogen that utilizes the quorum-sensing (QS) process to regulate the production of different virulence factors and biofilm. N-3-oxo-dodecanoyl-L-homoserine lactone (C12) is a key QS molecule of P. aeruginosa which interacts with the mammalian immune cells and modulates their function. Here, we investigated the molecular mechanism of C12-induced apoptosis in neutrophils. Our data show that C12 causes apoptosis in neutrophils through an elevation in cytosolic and mitochondrial Ca2+ levels. Besides, C12 induces phosphatidylserine (PS) exposure, mitochondrial membrane potential (MMP) depolarization, mitochondrial permeability transition pore (MPTP) formation and mitochondrial reactive oxygen species (mROS) generation. C12-induced rise in intracellular Ca2+ level is majorly contributed by endoplasmic reticulum store through the activation of inositol 1, 4, 5-triphosphate receptor. Intracellular calcium chelation inhibited C12-induced mitochondrial dysfunction and apoptosis. Further, inhibition of mitochondrial Ca2+ uniporter by ruthenium red or Ru360 abrogated C12-induced mitochondrial Ca2+ uptake, MMP loss, MPTP opening, mROS production, and PS exposure. These mechanistic insights are expected to provide a better understanding of the role of C12 in P. aeruginosa pathogenesis.

Mechanism underlying N-(3-oxo-dodecanoyl)-L-homoserine lactone mediated intracellular calcium mobilization in human platelets.

Acyl-homoserine lactones (AHLs), are the key autoinducer molecules that mediate Pseudomonas aeruginosa associated quorum sensing. P. aeruginosa produces two types of AHLs; N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12 HSL) and N-butyryl-L-homoserine lactone (C4 HSL). AHLs are not only regulating the virulence gene of bacteria but also influence the host cell functions by interkingdom signaling. In this study, we explored the mechanism of AHLs induced calcium mobilization in human platelets. We found that 3-oxo-C12 HSL but not C4 HSL induces intracellular calcium release. 3-oxo-C12 HSL induced calcium mobilization was majorly contributed from the dense tubular system (DTS). Furthermore, 3-oxo-C12 HSL also stimulates the store-operated Ca2+ entry (SOCE) in platelet. Intracellular calcium rise was significantly lowered in rotenone, and bafilomycin pre-treated platelets suggesting partial involvement of mitochondria and acidic vacuoles. The significant effect of 3-oxo-C12 HSL on calcium mobilization can alter the platelet functions that might results in thrombotic disorders in individuals infected with P. aeruginosa.

RENAL nephrometry score: Predicting perioperative outcomes following open partial nephrectomy.

BACKGROUND: Partial nephrectomy has emerged as a standard treatment for small renal masses offering oncologic control equivalent to radical nephrectomy, with preservation of renal function and evidence for equivalent survival. In this study, we evaluated RENAL nephrometry score (RNS) in predicting perioperative outcomes in patients with partial nephrectomy. MATERIALS AND METHODS: This was a prospective observational study conducted from February 2016 to August 2017 which included patients who underwent partial nephrectomy. The patients were divided into three groups depending on the complexity scores (low, moderate, and high). Tumors were assigned RNS and tumor-node-metastasis staging of the clinically malignant tumors was done. Blood loss, warm ischemia time (WIT), and surgical complications were assessed. RESULTS: A total of 20 patients underwent open partial nephrectomy during the study. There were 4 (20%) low, 11 (55%) moderate, and 5 (25%) high-complexity lesions. Blood loss was significantly different in three groups. All the cases in high-complexity group were performed with clamping the renal vessels with a mean WIT of 29 min. The overall complication rates were significantly different between the groups (P = 0.007); however, majority of the complications were low grade (Grades I and II) and were managed conservatively. CONCLUSION: In the present study, RNS was correlated with predicting surgical access route, need for clamping during partial nephrectomy, blood loss, decrease in glomerular filtration rate of operated kidneys, postoperative complications, and tumor grade.

Designing quorum sensing inhibitors of Pseudomonas aeruginosa utilizing FabI: an enzymic drug target from fatty acid synthesis pathway.

Pseudomonas aeruginosa infections are a leading cause of death in patients suffering from respiratory diseases. The multidrug-resistant nature of Pseudomonas is potentiated by a process known as quorum sensing. The aim of this study was to reveal new inhibitors of a well-validated but quite unexplored target, enoyl-ACP reductase, which contributes acyl chain lengths of N-acyl homoserine lactones that are major signaling molecules in gram-negative bacteria. In the present study, the crystal structure of FabI (PDB, ID 4NR0) was used for the structure-based identification of quorum sensing inhibitors of Pseudomonas aeruginosa. Active site residues of FabI were identified from the complex of FabI with triclosan and these active site residues were further used to screen for potential inhibitors from natural database. Three-dimensional structures of the 75 natural compounds were retrieved from the ZINC database and screened using PyRX software against FabI. Thirty-eight molecules from the initial screening were sorted on the basis of binding energy, using the known inhibitor triclosan as a standard. These molecules were subjected to various secondary filters, such as Lipinski's Rule of Five, ADME, and toxicity. Finally, eight lead-like molecules were obtained after their evaluation for drug-like characteristics. The present study will open a new window for designing QS inhibitors against P. aeruginosa.

Hypertension as Determinant of Hyperuricemia: A Case Control Study from the Sub-Himalayan Region in North India.

Background: Association between hyperuricemia and hypertension has been recognized for many years. Whether hyperuricemia is the cause or the effect is debatable. Materials and methods: This case control study was conducted to assess serum uric acid (SUA) levels in fifty newly diagnosed essential hypertensive patients and fifty normotensive controls which were matched for age and sex. Detailed anthropometric characteristics including height, weight, body mass index and waist hip ratio were measured. Hypertension was classified according to Joint National Committee (JNC) 7 criteria. Hyperuricemia was defined as SUA level of 6.8mg/dl or more in both men and women. SUA was measured by uricase method. Before collecting the blood samples, patients were advised to proceed on overnight fast of minimum eight hrs. Student's t­test for mean of continuous variables and Chi­square test for proportions were used for statistical significance. Results: Present study included 50 newly diagnosed cases of essential hypertension and 50 age and sex matched normotensive healthy volunteer. Prevalence of hyperuricemia was 24% among the cases and 6% among the controls (P < 0 .05). Odds ratio was 4.9 (Cl=1.3 to 18.8). The mean SUA was significantly higher in the cases (5.5±1.7 mg/dl) than in the controls (4.9±1.1 mg/dl; P< 0.05). Odds ratio in male hyperuricemic hypertensive versus hyperuricemic normotensive was 6(CI=1.0 to 33.2) and 4.46(CI=0.4 to 42.5) among female hyperuricemic hypertensive versus hyperuricemic normotensives. Conclusion: Strong positive association was observed between hypertension and hyperuricemia in both male and female patients in this study.

Pseudomonas aeruginosa quorum sensing molecule N-3-oxo-dodecanoyl-l-homoserine lactone activates human platelets through intracellular calcium-mediated ROS generation.

Pseudomonas aeruginosa, an opportunistic pathogen release N-3-oxo-dodecanoyl-l-homoserine lactone (3-oxo-C12HSL) and N-butyryl-l-homoserine lactone (C4-HSL) quorum sensing (QS) molecules to regulate various virulence factors responsible for infection in the host. 3-oxo-C12 HSL not only regulates the bacterial gene expression but also modulates the host cell system. Thus, it is pertinent to evaluate the effect of these QS molecules on blood platelets which is responsible for the maintenance of hemostasis and thrombus formation. Here, in the present study, we showed that 3-oxo-C12 HSL activates platelets in a dose-dependent manner and induces intracellular calcium-mediated reactive oxygen species (ROS) release, whereas no such effect was observed with C4-HSL. 3-oxo-C12 HSL stimulated ROS release was mediated by NADPH oxidase. Results confirmed the involvement of phospholipase C (PLC) and IP3 receptor behind intracellular calcium-mediated ROS generation. The impact of 3-oxo-C12 HSL on platelet activation suggests that it could interfere and alter the normal function of platelet in individuals infected with P. aeruginosa.

Exploring the impact of parthenolide as anti-quorum sensing and anti-biofilm agent against Pseudomonas aeruginosa.

AIMS: Pseudomonas aeruginosa is a well-known pathogen responsible for various infections due to its capability to develop biofilm and various virulent phenotypes that are regulated by quorum sensing. Pathogenesis of the bacteria may be halted by interfering with the signaling molecules and the quorum sensing receptors. Therefore, the present study explores the potential of parthenolide, a sesquiterpene lactone of feverfew plant, as a promising candidate against P. aeruginosa PAO1 associated virulence factors and biofilm. MAIN METHODS: Effect of parthenolide on virulence and biofilm formation of P. aeruginosa was studied using standard protocols. Mechanism of action was studied using Real-time PCR as well as molecular docking studies. KEY FINDINGS: Significant decrease in virulence factors and biofilm formation was observed when treated with the sub-MIC concentration (1 mM) of parthenolide. Gene expression studies showed the down-regulation of autoinducer synthase (lasI, rhlI) as well as their receptors (lasR and rhlR) with remarked repression of lasR by 57% compared to the control. Biofilm-associated fluorescent microscopic studies after staining with FITC-ConA and propidium iodide showed reduced extracellular polymeric substance (EPS) production and killing of bacterial cells after treatment with parthenolide. SIGNIFICANCE: The study is important as it reports for the first time the potential of parthenolide as an anti-quorum and anti-biofilm agent. This study will be helpful in designing of new quorum sensing inhibitors that help in the eradication of infections and can be given in combination with the antibiotics.

Pseudomonas aeruginosa auto inducer3-oxo-C12-HSL exerts bacteriostatic effect and inhibits Staphylococcus epidermidis biofilm.

Pseudomonas aeruginosa has evolved the 3-oxo-C12-HSL and C4-HSL based quorum sensing system which is responsible for the regulation of various virulence factors and helps to dominates over other bacterial species. Staphylococcus epidermidis has frequently been reported with P. aeruginosa while the role of C4-HSL and 3-oxo-C12-HSL on the S. epidermidis had widely been unexplored, and as per our knowledge, this is the first report on the impact of C4-HSL and 3-oxo-C12-HSL overS. epidermidis growth and biofilm. We found that among the two AHL molecules; only 3-oxo-C12-HSL was able to exert a significant effect in all the experiments including growth and biofilm of S. epidermidis. 3-oxo-C12-HSL at 100 µM and 200 µM concentrations were able to initiate the apparent transient type of planktonic growth inhibition in S. epidermidis. Microscopic analysis and biofilm quantification assay showed the inhibitory effect of 3-oxo-C12-HSL against S. epidermidis biofilm, initial attachment, and EPS production. The study concludes that P. aeruginosa associated 3-oxo-C12-HSL exerts the inhibitory effect on S. epidermidis growth and biofilms and thus it may also help Pseudomonasto dominate under the co-infection conditions.