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Quorum sensing

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https://www.readbyqxmd.com/read/28077586/redeploying-%C3%AE-lactam-antibiotics-as-a-novel-antivirulence-strategy-for-the-treatment-of-methicillin-resistant-staphylococcus-aureus-infections
#1
Elaine M Waters, Justine K Rudkin, Simone Coughlan, Geremy C Clair, Joshua N Adkins, Suzanna Gore, Guoqing Xia, Nikki S Black, Tim Downing, Eoghan O'Neill, Aras Kadioglu, James P O'Gara
Innovative approaches to the use of existing antibiotics is an important strategy in efforts to address the escalating antimicrobial resistance crisis. We report a new approach to the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections by demonstrating that oxacillin can be used to significantly attenuate the virulence of MRSA despite the pathogen being resistant to this drug. Using mechanistic in vitro assays and in vivo models of invasive pneumonia and sepsis, we show that oxacillin-treated MRSA strains are significantly attenuated in virulence...
January 1, 2017: Journal of Infectious Diseases
https://www.readbyqxmd.com/read/28077337/stress-hormone-epinephrine-adrenaline-and-norepinephrine-noradrenaline-effects-on-the-anaerobic-bacteria
#2
REVIEW
Lyudmila Boyanova
Microbial endocrinology is a relatively new research area that already encompasses the anaerobes. Stress hormones, epinephrine and norepinephrine, can affect the growth of anaerobic bacteria such as Fusobacterium nucleatum, Prevotella spp., Porhyromonas spp., Tanerella forsythia and Propionibacterium acnes and can increase virulence gene expression, iron acquisition and many virulence factors of some anaerobic species such as Clostridium perfringens, Porphyromonas gingivalis and Brachyspira pilosicoli. Epinephrine and norepinephrine effects can lead to a growth increase or decrease, or no effect on the growth of the anaerobes...
January 8, 2017: Anaerobe
https://www.readbyqxmd.com/read/28075113/pseudomonas-aeruginosa-lasr%C3%A2-dna-binding-is-directly-inhibited-by-quorum-sensing-antagonists
#3
Emma G Suneby, Leslie R Herndon, Tanya L Schneider
Inhibition of quorum sensing in Pseudomonas aeruginosa is of interest as a possible antivirulence strategy for this pathogenic bacterium. The LasR regulator protein is important in coordinating gene expression in response to quorum sensing signaling molecules. One predominant strategy for LasR inhibition is the development of small-molecule antagonists that mimic the native autoinducer, though the mechanism by which they inactivate LasR is not known. This work reveals that multiple antagonists function by binding to and stabilizing LasR in a conformation that renders it unable to bind DNA...
January 11, 2017: ACS Infectious Diseases
https://www.readbyqxmd.com/read/28069817/quorum-sensing-regulators-are-required-for-metabolic-fitness-in-vibrio-parahaemolyticus
#4
Sai Siddarth Kalburge, Megan R Carpenter, Sharon Rozovsky, E Fidelma Boyd
Quorum sensing (QS) is a process by which bacteria alter gene expression in response to cell density changes. In Vibrio species, at low cell density, the sigma 54-dependent response regulator LuxO, is active, and regulates the two QS master regulators AphA, which is induced and OpaR, which is repressed. At high cell density the opposite occurs, LuxO is inactive, therefore OpaR is induced and AphA is repressed. In V. parahaemolyticus, a significant enteric pathogen of humans, the role of these regulators in pathogenesis is less known...
January 9, 2017: Infection and Immunity
https://www.readbyqxmd.com/read/28069219/ultrasonic-assisted-synthesis-of-1-4-disubstituted-1-2-3-triazoles-via-various-terminal-acetylenes-and-azide-and-their-quorum-sensing-inhibition
#5
Da-Wei Zhang, Yu-Min Zhang, Jing Li, Tian-Qi Zhao, Qiang Gu, Feng Lin
An efficient synthesis of 1,4-disubstituted 1,2,3-triazole derivatives was studied. 1,4-Disubstituted 1,2,3-triazoles containing isoxazole and thymidine structures were synthesized in 84-96% yields starting from various terminal isoxazole ether alkynes and β-thymidine azide derivatives via a 1,3-dispolar cycloaddition using copper acetate, sodium ascorbate as the catalyst under ultrasonic assisted condition. All the target compounds were characterized by HRMS, FT-IR, (1)H NMR and (13)C NMR spectroscopy. Furthermore, the quorum sensing inhibitory activities of synthesized compounds were evaluated with Chromobacterium violaceum (C...
May 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28068190/er-yag-laser-irradiation-induces-behavioral-changes-in-v-harveyi
#6
Idan Redenski, Sharonit Sahar-Helft, Adam Stabholz, Doron Steinberg
OBJECTIVES: Laser technologies have many different applications in medical, agricultural, and industrial fields. Studies have shown several effects of laser energy on different bacterial species, in a wide variety of settings. Recent reports have found that one of the unique features of bacteria is their ability to communicate among themselves (quorum sensing). We sought to investigate whether low-energy laser irradiation affects bacterial behavior, which is regulated by quorum sensing...
January 9, 2017: Photomedicine and Laser Surgery
https://www.readbyqxmd.com/read/28067833/contribution-of-the-rgfd-quorum-sensing-peptide-to-rgf-regulation-and-host-cell-association-in-group-b-streptococcus
#7
Robert E Parker, David Knupp, Rim Al Safadi, Agnѐs Rosenau, Shannon D Manning
Streptococcus agalactiae (group B Streptococcus; GBS) is a common inhabitant of the genitourinary and/or gastrointestinal tract in up to 40% of healthy adults; however, this opportunistic pathogen is able to breach restrictive host barriers to cause disease and persist in harsh and changing conditions. This study sought to identify a role for quorum sensing, a form of cell to cell communication, in the regulation of the fibrinogen-binding (rgfBDAC) two-component system and the ability to associate with decidualized endometrial cells in vitro...
January 6, 2017: Genes
https://www.readbyqxmd.com/read/28067778/quorum-sensing-regulation-of-competence-and-bacteriocins-in-streptococcus-pneumoniae-and-mutans
#8
REVIEW
Erin Shanker, Michael J Federle
The human pathogens Streptococcus pneumoniae and Streptococcus mutans have both evolved complex quorum sensing (QS) systems that regulate the production of bacteriocins and the entry into the competent state, a requirement for natural transformation. Natural transformation provides bacteria with a mechanism to repair damaged genes or as a source of new advantageous traits. In S. pneumoniae, the competence pathway is controlled by the two-component signal transduction pathway ComCDE, which directly regulates SigX, the alternative sigma factor required for the initiation into competence...
January 5, 2017: Genes
https://www.readbyqxmd.com/read/28065820/bioavailability-enhanced-resveramax%C3%A2-modulates-quorum-sensing-and-inhibits-biofilm-formation-in-pseudomonas-aeruginosa-pao1
#9
H S Vasavi, H V Sudeep, H B Lingaraju, K Shyam Prasad
Quorum sensing (QS), a cell-to-cell communication mechanism present in many bacterial species plays a key role in regulating the virulence factor and biofilm formation in many pathogens, which causes severe public health risk. Therefore, interfering with QS mechanism offers an attractive strategy to combat bacterial infections. In the present study, anti-QS activity of a novel resveratrol formulation, Resveramax™, was detected using Chromobacterium violaceum biosensor bioassay and the effect of Resveramax on QS-regulated phenotypes in Pseudomonas aeruginosa PAO1 was assessed by standard protocols...
January 5, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28065658/functional-plasticity-of-the-agrc-receptor-histidine-kinase-required-for-staphylococcal-virulence
#10
Boyuan Wang, Aishan Zhao, Qian Xie, Paul Dominic Olinares, Brian T Chait, Richard P Novick, Tom W Muir
Staphylococcus aureus employs the receptor histidine kinase (RHK), AgrC, to detect quorum-sensing (QS) pheromones, the autoinducer peptides (AIPs), which regulate the virulence of the bacterium. Variation in the QS circuit divides S. aureus into four subgroups, each producing a specific AIP-AgrC pair. While the timing of QS induction is known to differ among these subgroups, the molecular basis of this phenomenon is unknown. Here, we report the successful reconstitution of several AgrC variants and show that the agonist-induced activity of the receptors varies in a manner that accounts for these temporal differences in QS induction...
December 30, 2016: Cell Chemical Biology
https://www.readbyqxmd.com/read/28062286/qseb-mediates-biofilm-formation-and-invasion-in-salmonella-enterica-serovar-typhi
#11
Ying Ji, Wenliang Li, Ying Zhang, Long Chen, Yiquan Zhang, Xueming Zheng, Xinxiang Huang, Bin Ni
QseB is a response regulator of the QseBC two-component system (TCS) which is associated with quorum sensing and functions as a global regulator of flagella, biofilm formation, and virulence. The function of QseB and its interaction with QseC has been the subject of study in some organisms, however, little work was done in Salmonella enterica serovar Typhi (S. Typhi). The objective of this study was to investigate the effect of QseB on biofilm formation and virulence in S. Typhi. It showed that the biofilm formation ability of qseC mutant was limited as compared to the wild type strain...
January 3, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28062182/exposure-of-airway-epithelial-cells-to-pseudomonas-aeruginosa-biofilm-derived-quorum-sensing-molecules-decrease-the-activity-of-the-anti-oxidant-response-element-bound-by-nrf2
#12
Lucie Roussel, Simon Rousseau
Chronic bacterial infections in cystic fibrosis lung disease are often characterized by Pseudomonas aeruginosa biofilms that are regulated by bacterial intercellular signals termed quorum sensing (QS), such as N-(3-oxododecanoyl)-l-homoserine lactone (3OC12-HSL). This study reports that biofilm-derived exoproducts decrease the transcriptional activity of the anti-oxidant response element in bronchial epithelial cells. In a live co-culture assay of BEAS-2B cells and P. aeruginosa biofilm, the QS molecule 3OC12-HSL was an important but not sole contributor to the inhibition of basal NRF2 luciferase reporter activity...
January 4, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28056745/exploiting-quorum-sensing-inhibition-for-the-control-of-pseudomonas-aeruginosa-and-acinetobacter-baumannii-biofilms
#13
Israel Castillo-Juarez, Luis Esaú López-Jácome, Gloria Soberón-Chávez, María Tomás, Jintae Lee, Paulina Castañeda-Tamez, Iván Ángelo Hernández-Bárragan, Martha Yumiko Cruz-Muñiz, Toshinari Maeda, Thomas K Wood, Rodolfo García-Contreras
Pseudomonas aeruginosa and Acinetobacter baumannii are two of the main bacteria responsible for nosocomial infections; both organisms are resistant to several classes of antibiotics making their infections very difficult to treat. Moreover, they possess a remarkable ability to form biofilms, which further enhances their antimicrobial resistance. Both organisms coordinate their formation of biofilms and their expression of virulence factors through quorum sensing, a system that regulates gene expression at high cell densities and that plays a key role in the establishment of bacterial infections...
January 5, 2017: Current Topics in Medicinal Chemistry
https://www.readbyqxmd.com/read/28056742/fungal-biofilm-a-real-obstacle-against-an-efficient-therapy-lessons-from-candida
#14
Thaís Pereira de Mello, Lívia de Souza Ramos, Lys Adriana Braga-Silva, Marta Helena Branquinha, André Luis Souza Dos Santos
The past decades have witnessed a dramatic increase in invasive fungal infections, especially caused by different species belonging to the Candida genus. Nowadays, even after many improvements in several medical procedures, Candida infections (candidiasis) still account for an unacceptable high rate of morbimortality in hospital settings. Corroborating this statement, fungal biofilms formed on both abiotic and living surfaces are responsible for an important medical and economic burden, since biofilm lifestyle confers numerous advantages to the pathogens, including high tolerance to environmental stresses such as antimicrobials and host immune responses...
January 5, 2017: Current Topics in Medicinal Chemistry
https://www.readbyqxmd.com/read/28054641/quorum-quenching-limits-quorum-sensing-exploitation-by-signal-negative-invaders
#15
Mélanie Tannières, Julien Lang, Claudie Barnier, Jacqui A Shykoff, Denis Faure
Some bacteria produce and perceive quorum-sensing (QS) signals that coordinate several behaviours, including the costly processes that are exoenzyme production and plasmid transfer. In the case of plasmid transfer, the emergence of QS signal-altered invaders and their policing are poorly documented. In Agrobacterium tumefaciens, the virulence Ti-plasmid encodes both synthesis and sensing of QS-signals, which promote its transfer from a donor to a recipient cell. Here, we reported that QS-altered A. tumefaciens mutants arose during experimental evolution...
January 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28049617/synthesis-of-antimicrobial-glucosamides-as-bacterial-quorum-sensing-mechanism-inhibitors
#16
Nripendra N Biswas, Tsz Tin Yu, Önder Kimyon, Shashidhar Nizalapur, Christopher R Gardner, Mike Manefield, Renate Griffith, David StC Black, Naresh Kumar
Bacteria communicate with one another and regulate their pathogenicity through a phenomenon known as quorum sensing (QS). When the bacterial colony reaches a threshold density, the QS system induces the production of virulence factors and the formation of biofilms, a powerful defence system against the host's immune responses. The glucosamine monomer has been shown to disrupt the bacterial QS system by inhibiting autoinducer (AI) signalling molecules such as the acyl-homoserine lactones (AHLs). In this study, the synthesis of acetoxy-glucosamides 8, hydroxy-glucosamides 9 and 3-oxo-glucosamides 12 was performed via the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl) and N,N'-dicyclohexylcarbodiimide (DCC) coupling methods...
December 21, 2016: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/28045495/bacterial-networks-on-hydrophobic-micropillars
#17
Zeinab Jahed, Hamed Shahsavan, Mohit S Verma, Jacob L Rogowski, Brandon B Seo, Boxin Zhao, Ting Y Tsui, Frank X Gu, Mohammad R K Mofrad
Bacteria have evolved as intelligent microorganisms that can colonize and form highly structured and cooperative multicellular communities with sophisticated singular and collective behaviors. The initial stages of colony formation and intercellular communication are particularly important to understand and depend highly on the spatial organization of cells. Controlling the distribution and growth of bacterial cells at the nanoscale is, therefore, of great interest in understanding the mechanisms of cell-cell communication at the initial stages of colony formation...
January 9, 2017: ACS Nano
https://www.readbyqxmd.com/read/28043869/isolation-of-rhamnolipids-producing-cultures-from-faeces-influence-of-interspecies-communication-on-the-yield-of-rhamnolipid-congeners
#18
Marta Woźniak-Karczewska, Kamila Myszka, Agata Sznajdrowska, Alicja Szulc, Agnieszka Zgoła-Grześkowiak, Łukasz Ławniczak, Philippe F-X Corvini, Łukasz Chrzanowski
The aim of this study was to evaluate the ability of bacterial cultures isolated from cattle, poultry or pig faeces and manure to produce rhamnolipids, as well as to investigate the influence of interspecies communication on possible quantitative differences in the production of rhamnolipid congeners. Initial screening methods (oil spreading, drop collapse, haemolytic activity and emulsification activity) showed that approximately 36% of the 51 isolated cultures exhibited the ability to produce biosurfactants...
December 30, 2016: New Biotechnology
https://www.readbyqxmd.com/read/28036056/genetic-regulation-of-virulence-and-antibiotic-resistance-in-acinetobacter-baumannii
#19
REVIEW
Carsten Kröger, Stefani C Kary, Kristina Schauer, Andrew D S Cameron
Multidrug resistant microorganisms are forecast to become the single biggest challenge to medical care in the 21st century. Over the last decades, members of the genus Acinetobacter have emerged as bacterial opportunistic pathogens, in particular as challenging nosocomial pathogens because of the rapid evolution of antimicrobial resistances. Although we lack fundamental biological insight into virulence mechanisms, an increasing number of researchers are working to identify virulence factors and to study antibiotic resistance...
December 28, 2016: Genes
https://www.readbyqxmd.com/read/28035988/antibiotic-resistant-superbugs-assessment-of-the-interrelationship-of-occurrence-in-clinical-settings-and-environmental-niches
#20
REVIEW
Anthony Ayodeji Adegoke, Adekunle Christopher Faleye, Gulshan Singh, Thor Axel Stenström
The increasing threat to global health posed by antibiotic resistance remains of serious concern. Human health remains at higher risk due to several reported therapeutic failures to many life threatening drug resistant microbial infections. The resultant effects have been prolonged hospital stay, higher cost of alternative therapy, increased mortality, etc. This opinionated review considers the two main concerns in integrated human health risk assessment (i.e., residual antibiotics and antibiotic resistant genes) in various compartments of human environment, as well as clinical dynamics associated with the development and transfer of antibiotic resistance (AR)...
December 27, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
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