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Polymyxin B

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https://www.readbyqxmd.com/read/28807222/polymyxin-b-as-an-inhibitor-of-lipopolysaccharides-contamination-of-herb-crude-polysaccharides-in-mononuclear-cells
#1
Xiao-Xiao Lu, Yi-Fan Jiang, Hong Li, Ying-Ye Ou, Zhi-De Zhang, Hong-Ye DI, Dao-Feng Chen, Yun-Yi Zhang
Lipopolysaccharides (LPS) contamination in herbal crude polysaccharides is inevitable. The present study was performed to explore the effect of polymyxin B on abolishing the influence of LPS contamination in mononuclear cells. LPS was pretreated with polymyxin B sulfate (PB) at different concentrations for 1, 5 or 24 h, and then used to stimulate RAW264.7 and mouse peritoneal macrophages (MPMs). The nitric oxide (NO) and tumor necrosis factor-α (TNF-α) in cell culture supernatant, as the indications of cell response, were assayed...
July 2017: Chinese Journal of Natural Medicines
https://www.readbyqxmd.com/read/28805387/polymyxin-binding-to-the-bacterial-outer-membrane-reveals-cation-displacement-and-increasing-membrane-curvature-in-susceptible-but-not-in-resistant-lps-chemotypes
#2
Denys Ewerton da Silva Santos, Laércio Pol-Fachin, Roberto D Lins, Thereza A Soares
Lipid-A is the causative agent of Gram-negative sepsis and responsible for increasingly high mortality rate among hospitalized patients. Compounds that bind Lipid-A can limit this inflammatory process. The cationic antimicrobial peptide polymyxin B (Pmx-B) is one of the simplest molecules capable of selectively bind to Lipid-A, and may serve as a model for further development of Lipid-A binding agents. Gram-negative bacteria resistance to Pmx-B relies on the upregulation of a number of regulatory systems, which promote chemical modifications of the LPS structure, and leads to major changes in the physical-chemical properties of the outer membrane...
August 14, 2017: Journal of Chemical Information and Modeling
https://www.readbyqxmd.com/read/28804940/effects-of-polymyxin-b-on-tnf-%C3%AE-production-in-equine-whole-blood-stimulated-with-three-different-bacterial-toxins
#3
J R Bauquier, B S Tennent-Brown, E Tudor, S R Bailey
Polymyxin-B is used to treat equine systemic inflammation. Bacterial toxins other than lipopolysaccharide (LPS) contribute to systemic inflammation but the effects of polymyxin-B on these are poorly defined. Whole blood aliquots from six healthy horses diluted 1:1 with RPMI were incubated for 21 hr with 1 μg/ml of LPS, lipoteichoic acid (LTA) or peptidoglycan (PGN) in the presence of increasing concentrations of polymyxin-B (10-3000 μg/ml). A murine L929 fibroblast bioassay was used to measure TNF-α activity...
August 14, 2017: Journal of Veterinary Pharmacology and Therapeutics
https://www.readbyqxmd.com/read/28803214/self-defensive-antibiotic-loaded-layer-by-layer-coatings-imaging-of-localized-bacterial-acidification-and-ph-triggering-of-antibiotic-release
#4
Victoria Albright, Iryna Zhuk, Yuhao Wang, Victor Selin, Betsy van de Belt-Gritter, Henk J Busscher, Henny C van der Mei, Svetlana Sukhishvili
Self-defensive antibiotic-loaded coatings have shown promise in inhibiting growth of pathogenic bacteria adhering to biomaterial implants and devices, but direct proof that their antibacterial release is triggered by bacterially-induced acidification of the immediate environment under buffered conditions remained elusive. Here, we demonstrate that Staphylococcus aureus and Escherichia coli adhering to such coatings generate highly localized acidification, even in buffered conditions, to activate pH-triggered, self-defensive antibiotic release...
August 9, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28797068/virulence-profiles-and-innate-immune-responses-against-highly-lethal-multidrug-resistant-nosocomial-isolates-of-acinetobacter-baumannii-from-a-tertiary-care-hospital-in-mexico
#5
Roberto Rosales-Reyes, Catalina Gayosso-Vázquez, José Luis Fernández-Vázquez, Ma Dolores Jarillo-Quijada, César Rivera-Benítez, José Ignacio Santos-Preciado, María Dolores Alcántar-Curiel
Virulence profiles and innate immune responses were studied in Acinetobacter baumannii from nosocomial infections collected over one year in a tertiary care hospital in Mexico. A. baumannii were identified by VITEK 2 System followed by susceptibility tests. Carbapenemase genes, active efflux mechanism to imipenem and meropenem and outer membrane proteins profile were analyzed to evaluate their role on the activity of carbapenem resistance. All isolates were genotyped by pulsed field gel electrophoresis. The ability to form biofilm was determined on a polystyrene surface...
2017: PloS One
https://www.readbyqxmd.com/read/28765224/genome-wide-sensitivity-analysis-of-the-microsymbiont-sinorhizobium-meliloti-to-symbiotically-important-defensin-like-host-peptides
#6
Markus F F Arnold, Mohammed Shabab, Jon Penterman, Kevin L Boehme, Joel S Griffitts, Graham C Walker
The model legume species Medicago truncatula expresses more than 700 nodule-specific cysteine-rich (NCR) signaling peptides that mediate the differentiation of Sinorhizobium meliloti bacteria into nitrogen-fixing bacteroids. NCR peptides are essential for a successful symbiosis in legume plants of the inverted-repeat-lacking clade (IRLC) and show similarity to mammalian defensins. In addition to signaling functions, many NCR peptides exhibit antimicrobial activity in vitro and in vivo Bacterial resistance to these antimicrobial activities is likely to be important for symbiosis...
August 1, 2017: MBio
https://www.readbyqxmd.com/read/28762368/antibiotic-susceptibility-profiles-of-non-fermenting-gram-negative-bacilli-at-a-tertiary-care-hospital-in-patiala-india
#7
Udhayvir Singh Grewal, Rupinder Bakshi, Geeta Walia, Parth Rajeshbhai Shah
BACKGROUND: Non-fermenting Gram-negative bacilli (NFGNB) have emerged as a major cause of healthcare-associated infections and are innately resistant to many antibiotics. AIM: The aim of this study was to determine the prevalence of NFGNB isolated from various clinical specimens and evaluate their antimicrobial susceptibility profiles. MATERIALS AND METHODS: This retrospective study was done at our Department of Microbiology from December 2015 to December 2016...
April 2017: Nigerian Postgraduate Medical Journal
https://www.readbyqxmd.com/read/28761764/resurgence-of-polymyxin-b-for-mdr-xdr-gram-negative-infections-an-overview-of-current-evidence
#8
REVIEW
Suneel Kumar Garg, Omender Singh, Deven Juneja, Niraj Tyagi, Amandeep Singh Khurana, Amit Qamra, Salman Motlekar, Hanmant Barkate
Polymyxin B has resurged in recent years as a last resort therapy for Gram-negative multidrug-resistant (MDR) and extremely drug resistant (XDR) infections. Understanding newer evidence on polymyxin B is necessary to guide clinical decision making. Here, we present a literature review of polymyxin B in Gram-negative infections with update on its pharmacology.
2017: Critical Care Research and Practice
https://www.readbyqxmd.com/read/28750947/polymyxins-for-cns-infections-pharmacology-and-neurotoxicity
#9
REVIEW
Tony Velkov, Chongshan Dai, Giuseppe D Ciccotosto, Roberto Cappai, Daniel Hoyer, Jian Li
Central nervous system (CNS) infections caused by multi-drug resistant (MDR) Gram-negative bacteria present a major health and economic burden worldwide. Due to the nearly empty antibiotic discovery pipeline, polymyxins (i.e. polymyxin B and colistin) are used as the last-line therapy against Gram-negative 'superbugs' when all other treatment modalities have failed. The treatment of CNS infections due to multi-drug resistant Gram-negative bacteria is problematic and associated with high mortality rates. Colistin shows significant efficacy for the treatment of CNS infections caused by MDR Gram-negative bacteria that are resistant to all other antibiotics...
July 25, 2017: Pharmacology & Therapeutics
https://www.readbyqxmd.com/read/28747375/evaluation-of-the-rapid-polymyxin-np-test-for-polymyxin-b-resistance-detection-using-enterobacter-cloacae-and-enterobacter-aerogenes-isolates
#10
Shelby Simar, Diane Sibley, Deborah Ashcraft, George Pankey
Background: Polymyxin resistance is an increasing problem worldwide. Currently, determining susceptibility to polymyxins is problematic and lengthy. Polymyxins diffuse poorly into agar, potentially giving inaccurate disk diffusion and Etest results. A rapid screening test (2 h) for detection of polymyxin-resistance in Enterobacteriaceae, developed by Nordmann and Poirel (Rapid Polymyxin NP Test, 2016), detects glucose metabolization in the presence of polymyxins E and B via pH-induced color change. Sensitivity/specificity were 99...
July 26, 2017: Journal of Clinical Microbiology
https://www.readbyqxmd.com/read/28743810/polymyxin-combinations-combat-escherichia-coli-harboring-mcr-1-and-blandm-5-preparation-for-a-postantibiotic-era
#11
Zackery P Bulman, Liang Chen, Thomas J Walsh, Michael J Satlin, Yuli Qian, Jürgen B Bulitta, Charles A Peloquin, Patricia N Holden, Roger L Nation, Jian Li, Barry N Kreiswirth, Brian T Tsuji
The rapid increase of carbapenem resistance in Gram-negative bacteria has resurrected the importance of the polymyxin antibiotics. The recent discovery of plasmid-mediated polymyxin resistance (mcr-1) in carbapenem-resistant Enterobacteriaceae serves as an important indicator that the golden era of antibiotics is under serious threat. We assessed the bacterial killing of 15 different FDA-approved antibiotics alone and in combination with polymyxin B in time-killing experiments against Escherichia coli MCR1_NJ, the first reported isolate in the United States to coharbor mcr-1 and a New Delhi metallo-β-lactamase gene (blaNDM-5)...
July 25, 2017: MBio
https://www.readbyqxmd.com/read/28724927/dual-functionality-nanobioconjugates-targeting-intracellular-bacteria-in-cancer-cells-with-enhanced-antimicrobial-activity
#12
Rohini Singh, Smita Patil, Neetu Singh, Shalini Gupta
Bacterial drug resistance has emerged as a serious global threat mandating the development of novel methodologies that allow facile modulation of antimicrobial action in a controlled fashion. Conjugating antibiotics to nanoparticles helps to meet this goal by increasing the drug's overall avidity, bioavailability and easier internalisation into mammalian cells, targeting bacteria that otherwise escape antibacterial action by host cell-localisation. We used polymyxin B sulfate (PMB) and sushi peptide as model drugs against Gram-negative bacteria and established their enhanced antimicrobial activity on Escherichia coli (E...
July 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28724555/susceptibility-testing-for-the-polymyxins-two-steps-back-three-steps-forward
#13
Shawn Vasoo
Optimizing and standardizing susceptibility testing for the polymyxins have become a pressing issue given the rise multidrug-resistant Gram-negative bacilli. Recently both CLSI-EUCAST have recommended broth microdilution (BMD) (without polysorbate) as the reference method for polymyxin susceptibility testing. In this issue, Chew et al. (doi: https://doi.org/10.1128JCM.00268-17.) compare the performance of three commercial BMD panels and the Etest to reference BMD for polymyxin B and colistin, on 76 Enterobacteriaceae isolates (21 mcr-1 positive)...
July 19, 2017: Journal of Clinical Microbiology
https://www.readbyqxmd.com/read/28721845/combination-of-polymyxin-b-and-meropenem-eradicates-persister-cells-from-acinetobacter-baumannii-strains-in-exponential-growth
#14
Stephanie W Gallo, Carlos Alexandre S Ferreira, Sílvia D de Oliveira
No abstract text is available yet for this article.
July 18, 2017: Journal of Medical Microbiology
https://www.readbyqxmd.com/read/28716359/predictors-of-polymyxin-b-treatment-failure-in-gram-negative-healthcare-associated-infections-among-critically-ill-patients
#15
Bahiah Ismail, Mohd Nazri Shafei, Azian Harun, Saedah Ali, Mahamarowi Omar, Zakuan Zainy Deris
BACKGROUND: With increasing prevalence and spread of multidrug resistant Gram-negative infections, parenteral polymyxins resurged in clinical practice. The primary aim of the study was to determine the predictors of treatment failure and in-hospital mortality among critically ill patients treated with polymyxin B. METHODS: Demographic data, underlying diseases, procedures and details on polymyxin B therapy were retrospectively analyzed in a cohort of 84 patients who received intravenous polymyxin B in an intensive care unit from 2010 to 2014...
June 29, 2017: Journal of Microbiology, Immunology, and Infection, Wei Mian Yu Gan Ran za Zhi
https://www.readbyqxmd.com/read/28714872/immunomodulatory-activity-of-octenyl-succinic-anhydride-modified-porang-amorphophallus-oncophyllus-glucomannan-on-mouse-macrophage-like-j774-1-cells-and-mouse-primary-peritoneal-macrophages
#16
Sellen Gurusmatika, Kosuke Nishi, Eni Harmayani, Yudi Pranoto, Takuya Sugahara
Porang is a local plant of Indonesia, which has a high content of glucomannan. In this study, porang glucomannan (PG) was esterified with octenyl succinic anhydride (OSA) to enhance emulsion properties to be widely used in food industry. OSA-modified PG (OSA-PG) enhanced the phagocytosis activity of macrophage-like J774.1 cells and mouse peritoneal macrophages. In addition, OSA-PG increased the production of IL-6 and TNF-α by enhancing their gene expression. Immunoblot analysis displayed that OSA-PG tended to activate both nuclear factor-κB and mitogen-activated protein kinase cascades...
July 15, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28713357/extensively-drug-resistant-klebsiella-pneumoniae-causing-nosocomial-bloodstream-infections-in-china-molecular-investigation-of-antibiotic-resistance-determinants-informing-therapy-and-clinical-outcomes
#17
Wenzi Bi, Haiyang Liu, Rhys A Dunstan, Bin Li, Von Vergel L Torres, Jianming Cao, Lijiang Chen, Jonathan J Wilksch, Richard A Strugnell, Trevor Lithgow, Tieli Zhou
The rise in diversity of antimicrobial resistance phenotypes seen in Klebsiella pneumoniae is becoming a serious antibiotic management problem. We sought to investigate the molecular characteristics and clinical implications of extensively drug-resistant (XDR) K. pneumoniae isolated from different nosocomial bloodstream infections (BSIs) patients from July 2013 to November 2015. Even in combination treatment, meropenem did not protect against mortality of BSIs patients (P = 0.015). In contrast, tigecycline in combination with other antimicrobial agents significantly protected against mortality (P = 0...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28711154/western-diet-induced-dysbiosis-in-farnesoid-x-receptor-knockout-mice-causes-persistent-hepatic-inflammation-after-antibiotic-treatment
#18
Prasant K Jena, Lili Sheng, Hui-Xin Liu, Karen M Kalanetra, Annie Mirsoian, William J Murphy, Samuel W French, Viswanathan V Krishnan, David A Mills, Yu-Jui Yvonne Wan
Patients who have liver cirrhosis and liver cancer also have reduced farnesoid X receptor (FXR). The current study analyzes the effect of diet through microbiota that affect hepatic inflammation in FXR knockout (KO) mice. Wild-type and FXR KO mice were on a control (CD) or Western diet (WD) for 10 months. In addition, both CD- and WD-fed FXR KO male mice, which had hepatic lymphocyte and neutrophil infiltration, were treated by vancomycin, polymyxin B, and Abx (ampicillin, neomycin, metronidazole, and vancomycin)...
August 2017: American Journal of Pathology
https://www.readbyqxmd.com/read/28700048/distribution-of-the-bla-oxa-bla-veb-1-and-bla-ges-1-genes-and-resistance-patterns-of-esbl-producing-pseudomonas-aeruginosa-isolated-from-hospitals-in-tehran-and-qazvin-iran
#19
Sahar Amirkamali, Taghi Naserpour-Farivar, Khadijeh Azarhoosh, Amir Peymani
INTRODUCTION: Pseudomonas aeruginosa is one of the most common nosocomial pathogens. The emergence of extended spectrum β-lactamases (ESBLs) has been increasingly reported as a major clinical concern worldwide. The main aim of the present study was to determine the distribution of bla OXA, bla PER-1, bla VEB-1, and bla GES-1 genes among ESBL-producing P. aeruginosa isolated from two distinct provinces in Iran. METHODS: In this study, a total of 75 (27.5%) ESBL-producing isolates were identified from 273 P...
May 2017: Revista da Sociedade Brasileira de Medicina Tropical
https://www.readbyqxmd.com/read/28695731/investigating-the-interaction-of-octapeptin-a3-with-model-bacterial-membranes
#20
Mei-Ling Han, Hsin-Hui Shen, Karl A Hansford, Elena K Schneider, Sivashangarie Sivanesan, Kade D Roberts, Philip E Thompson, Anton P Le Brun, Yan Zhu, Marc-Antoine Sani, Frances Separovic, Mark A T Blaskovich, Mark A Baker, Samuel M Moskowitz, Matthew A Cooper, Jian Li, Tony Velkov
Octapeptins are cyclic lipopeptides with a broader spectrum of activity against fungi and polymyxin-resistant Gram-negative and Gram-positive bacteria. In the present study, we investigated the interaction of octapeptin A3 with asymmetric outer membrane models of Gram-negative pathogen Pseudomonas aeruginosa using neutron reflectometry, together with fluorimetric and calorimetry methods. For the first time, our neutron reflectometry results reveal that the interaction of octapeptin A3 with the Gram-negative outer membrane involves an initial transient polar interaction with the phospholipid and lipid A headgroups, followed by the penetration of the entire octapeptin molecule into the fatty acyl core of the outer membrane...
July 11, 2017: ACS Infectious Diseases
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