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Polymyxin-b

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https://www.readbyqxmd.com/read/28334005/multi-scale-model-of-drug-induced-adaptive-resistance-of-gram-negative-bacteria-to-polymyxin-b
#1
Wojciech Krzyzanski, Gauri G Rao
The purpose of this report is to apply multi-scale modeling using the theory of physiologically structured populations (PSP) to develop a mathematical model for antimicrobial resistance based on a heterogeneous distribution of receptors and affinities among bacterial cells. The theory has been tested on data obtained from an in vitro static time-kill infection model analyzing the pharmacodynamics of polymyxin B against Gram-negative bacteria. The drug binding parameter KD (dissociation equilibrium constant) is assumed to vary between the bacterial cells...
2017: PloS One
https://www.readbyqxmd.com/read/28333347/polymyxin-resistant-carbapenem-resistant-acinetobacter-baumannii-is-eradicated-by-a-triple-combination-of-agents-that-lack-individual-activity
#2
Justin R Lenhard, Visanu Thamlikitkul, Fernanda P Silveira, Samira M Garonzik, Xun Tao, Alan Forrest, Beom Soo Shin, Keith S Kaye, Jürgen B Bulitta, Roger L Nation, Jian Li, Brian T Tsuji
Objectives: The emergence of polymyxin resistance threatens to leave clinicians with few options for combatting drug-resistant Acinetobacter baumannii . The objectives of the current investigation were to define the in vitro emergence of polymyxin resistance and identify a combination regimen capable of eradicating A. baumannii with no apparent drug susceptibilities. Methods: Two clonally related, paired, A. baumannii isolates collected from a critically ill patient who developed colistin resistance while receiving colistin methanesulfonate in a clinical population pharmacokinetic study were evaluated: an A...
February 28, 2017: Journal of Antimicrobial Chemotherapy
https://www.readbyqxmd.com/read/28332430/preparation-of-pva-amino-multi-walled-carbon-nanotubes-nanocomposite-microspheres-for-endotoxin-adsorption
#3
Wenhui Zong, Jian Chen, Wenyan Han, Guanghui Cheng, Jie Chen, Yue Wang, Weichao Wang, Lailiang Ou, Yaoting Yu, Jie Shen
A novel polyvinyl alcohol-amino multi-walled carbon nanotube (PVA-AMWCNT) nanocomposite microsphere was prepared successfully for the first time and used for endotoxin removal. The resulting AMWCNT modified PVA microsphere was characterized by SEM, Raman spectrum and fluorescence image, which indicated AMWCNT was dispersed into the macropores of PVA microsphere uniformly. The PVA-AMWCNT microspheres showed better adsorption capability and faster adsorption equilibrium for endotoxin in aqueous solution when compared to the PVA microsphere with polymyxin B (PMB) as ligand...
March 23, 2017: Artificial Cells, Nanomedicine, and Biotechnology
https://www.readbyqxmd.com/read/28316480/inducible-spy-transcription-acts-as-a-sensor-for-envelope-stress-of-salmonella-typhimurium
#4
Seon Mi Jeong, Hwa Jeong Lee, Yoon Mee Park, Jin Seok Kim, Sang Dae Lee, Iel Soo Bang
Salmonella enterica infects a broad range of host animals, and zoonostic infection threatens both public health and the livestock and meat processing industries. Many antimicrobials have been developed to target Salmonella envelope that performs essential bacterial functions; however, there are very few analytical methods that can be used to validate the efficacy of these antimicrobials. In this study, to develop a potential biosensor for Salmonella envelope stress, we examined the transcription of the S. enterica serovar typhimurium spy gene, the ortholog of which in Escherichia coli encodes Spy (spheroplast protein y)...
2017: Korean Journal for Food Science of Animal Resources
https://www.readbyqxmd.com/read/28306723/the-redefinition-of-helicobacter-pylori-lipopolysaccharide-o-antigen-and-core-oligosaccharide-domains
#5
Hong Li, Tiandi Yang, Tingting Liao, Aleksandra W Debowski, Hans-Olof Nilsson, Alma Fulurija, Stuart M Haslam, Barbara Mulloy, Anne Dell, Keith A Stubbs, Barry J Marshall, Mohammed Benghezal
Helicobacter pylori lipopolysaccharide promotes chronic gastric colonisation through O-antigen host mimicry and resistance to mucosal antimicrobial peptides mediated primarily by modifications of the lipid A. The structural organisation of the core and O-antigen domains of H. pylori lipopolysaccharide remains unclear, as the O-antigen attachment site has still to be identified experimentally. Here, structural investigations of lipopolysaccharides purified from two wild-type strains and the O-antigen ligase mutant revealed that the H...
March 17, 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28302074/clonality-outer-membrane-proteins-profile-and-efflux-pump-in-kpc-producing-enterobacter-sp-in-brazil
#6
Juliana Ferraz Rosa, Camila Rizek, Ana Paula Marchi, Thais Guimaraes, Lourdes Miranda, Claudia Carrilho, Anna S Levin, Silvia F Costa
BACKGROUND: Carbapenems resistance in Enterobacter spp. has increased in the last decade, few studies, however, described the mechanisms of resistance in this bacterium. This study evaluated clonality and mechanisms of carbapenems resistance in clinical isolates of Enterobacter spp. identified in three hospitals in Brazil (Hospital A, B and C) over 7-year. METHODS: Antibiotics sensitivity, pulsed-field gel electrophoresis (PFGE), PCR for carbapenemase and efflux pump genes were performed for all carbapenems-resistant isolates...
March 17, 2017: BMC Microbiology
https://www.readbyqxmd.com/read/28300674/structure-activity-studies-on-polymyxin-derivatives-carrying-three-positive-charges-only-reveal-a-new-class-of-compounds-with-strong-antibacterial-activity
#7
Martti Vaara, Timo Vaara, Jonathan M Tyrrell
Recent years have brought in an increased interest to develop improved polymyxins. The currently used polymyxins, i.e. polymyxin B and colistin (polymyxin E) are pentacationic lipopeptides that possess a cyclic heptapeptide part with three positive charges, a linear "panhandle" part with two positive charges, and a fatty acyl tail. Unfortunately, their clinical use is shadowed by their notable nephrotoxicity. We have previously developed a polymyxin derivative NAB739 which lacks the positive charges in the linear part...
March 11, 2017: Peptides
https://www.readbyqxmd.com/read/28295668/dissemination-of-metallo-%C3%AE-lactamase-in-pseudomonas-aeruginosa-isolates-in-egypt-mutation-in-blavim-4
#8
Hany Hashem, Amro Hanora, Salah Abdalla, Alaa Shaeky, Alaa Saad
This study was designed to investigate the prevalence of metallo-β-lactamase (MBL) in Pseudomonas aeruginosa isolates collected from Suez Canal University Hospital in Ismailia, Egypt. Antibiotic susceptibility testing and phenotypic and genotypic screening for MBLs were performed on 147 isolates of P. aeruginosa. MICs were determined by agar dilution method for carbapenem that was ≥2 μg/mL for meropenem. MBL genes were detected by multiplex and monoplex PCR for P. aeruginosa-harbored plasmids. Mutation profile of sequenced MBL genes was screened using online software Clustal Omega...
March 15, 2017: APMIS: Acta Pathologica, Microbiologica, et Immunologica Scandinavica
https://www.readbyqxmd.com/read/28280277/preparation-and-antimicrobial-evaluation-of-polyion-complex-pic-nanoparticles-loaded-with-polymyxin-b
#9
Ignacio Insua, Sieta Majok, Anna F A Peacock, Anne Marie Krachler, Francisco Fernandez-Trillo
Here, we describe novel polyion complex (PIC) particles for the delivery of Polymyxin B (Pol-B), an antimicrobial peptide currently used in the clinic as a last resort antibiotic against multidrug-resistant gram-negative bacteria. A range of conditions for the controlled assembly of Pol-B with poly(styrene sulphonate) (PSS) has been identified which let us prepare stable colloidal PIC particles. This way, PIC particles containing different Pol-B:PSS ratios have been prepared and their stability under simulated physiological conditions (i...
February 2017: European Polymer Journal
https://www.readbyqxmd.com/read/28276116/epidemiology-of-bacterial-conjunctivitis-in-chinchillas-chinchilla-lanigera-49-cases-2005-to-2015
#10
S Ozawa, C Mans, Z Szabo, N Di Girolamo
OBJECTIVES: To evaluate the anamnesis, clinical signs, diagnostic test results, treatment and outcome of chinchillas diagnosed with bacterial conjunctivitis. METHODS: Medical records of 49 chinchillas diagnosed with bacterial conjunctivitis were retrospectively reviewed. Association between clinical signs and type of bacteria involved was determined by means of univariate logistic regression. RESULTS: 61·5% of the isolated bacteria were Gram-negative, and the most common bacterial species was Pseudomonas aeruginosa (50%), followed by Staphylococcus species (26·9%)...
April 2017: Journal of Small Animal Practice
https://www.readbyqxmd.com/read/28275006/polymyxins-antibacterial-activity-susceptibility-testing-and-resistance-mechanisms-encoded-by-plasmids-or-chromosomes
#11
REVIEW
Laurent Poirel, Aurélie Jayol, Patrice Nordmann
SUMMARYPolymyxins are well-established antibiotics that have recently regained significant interest as a consequence of the increasing incidence of infections due to multidrug-resistant Gram-negative bacteria. Colistin and polymyxin B are being seriously reconsidered as last-resort antibiotics in many areas where multidrug resistance is observed in clinical medicine. In parallel, the heavy use of polymyxins in veterinary medicine is currently being reconsidered due to increased reports of polymyxin-resistant bacteria...
April 2017: Clinical Microbiology Reviews
https://www.readbyqxmd.com/read/28268175/dissemination-of-carbapenem-resistant-acinetobacter-baumannii-in-patients-with-burn-injuries
#12
Saeed Shoja, Mojtaba Moosavian, Soodabeh Rostami, Abbas Farahani, Amir Peymani, Khadijeh Ahmadi, Nasim Ebrahimifard
BACKGROUND: Carbapenem-resistant Acinetobacter baumannii has emerged as an important cause of infection in burn patients. This study aimed to characterize the antimicrobial susceptibility pattern, determine the prevalence of oxacillinase and metallo-beta-lactamase (MBL) genes, and type the A. baumannii isolates obtained from burn patients. METHODS: During a 1-year period, a total of 40 nonduplicated isolates of A. baumannii were obtained from burn patients who were hospitalized in the Taleghani Burn Hospital in Ahvaz, in the southwest of Iran...
March 3, 2017: Journal of the Chinese Medical Association: JCMA
https://www.readbyqxmd.com/read/28258235/antibiotic-non-antibiotic-combinations-for-combating-extremely-drug-resistant-gram-negative-superbugs
#13
REVIEW
Elena K Schneider, Felisa Reyes-Ortega, Tony Velkov, Jian Li
The emergence of antimicrobial resistance of Gram-negative pathogens has become a worldwide crisis. The status quo for combating resistance is to employ synergistic combinations of antibiotics. Faced with this fast-approaching post-antibiotic era, it is critical that we devise strategies to prolong and maximize the clinical efficacy of existing antibiotics. Unfortunately, reports of extremely drug-resistant (XDR) Gram-negative pathogens have become more common. Combining antibiotics such as polymyxin B or the broad-spectrum tetracycline and minocycline with various FDA-approved non-antibiotic drugs have emerged as a novel combination strategy against otherwise untreatable XDR pathogens...
February 28, 2017: Essays in Biochemistry
https://www.readbyqxmd.com/read/28249575/first-report-on-bla-ndm-1-producing-acinetobacter-baumannii-in-three-clinical-isolates-from-ethiopia
#14
Michael Pritsch, Ahmed Zeynudin, Maxim Messerer, Simon Baumer, Gabriele Liegl, Soeren Schubert, Thomas Löscher, Michael Hoelscher, Tefara Belachew, Andrea Rachow, Andreas Wieser
BACKGROUND: Multidrug-resistant Gram-negative bacterial infections are recognized as one of the major threats to global health. In this study, we describe for the first time bla NDM-1 gene carrying organisms from Ethiopia consisting of three Acinetobacter baumannii isolates from patients in Jimma. METHODS: Besides phenotypic antimicrobial susceptibility testing, molecular strain typing and sequencing was performed to describe the phylogenetic relation of the Ethiopian isolates in detail in relation to published isolates from all over the globe...
March 1, 2017: BMC Infectious Diseases
https://www.readbyqxmd.com/read/28248483/a-fluorescent-probe-distinguishes-between-inhibition-of-early-and-late-steps-of-lipopolysaccharide-biogenesis-in-whole-cells
#15
Eileen Moison, Ran Xie, Ge Zhang, Matthew D Lebar, Timothy C Meredith, Daniel Kahne
Lipopolysaccharide (LPS) biogenesis in Gram-negative organisms involves its biosynthesis in the cytoplasm and subsequent transport across three cellular compartments to the cell surface. We developed a fluorescent probe that allows us to determine the spatial distribution of LPS in whole cells. We show that polymyxin B nonapeptide (PMBN) containing a dansyl fluorophore specifically binds to LPS in membranes. We show that this probe detects decreases in LPS levels on the cell surface when LPS biosynthesis is inhibited at an early step...
March 9, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28246454/molecular-identification-and-histopathological-study-of-natural-streptococcus-agalactiae-infection-in-hybrid-tilapia-oreochromis-niloticus
#16
A A Laith, Mohd Azmi Ambak, Marina Hassan, Shahreza Md Sheriff, Musa Nadirah, Ahmad Shuhaimi Draman, Wahidah Wahab, Wan Nurhafizah Wan Ibrahim, Alia Syafiqah Aznan, Amina Jabar, Musa Najiah
AIM: The main objective of this study was to emphasize on histopathological examinations and molecular identification of Streptococcus agalactiae isolated from natural infections in hybrid tilapia (Oreochromis niloticus) in Temerloh Pahang, Malaysia, as well as to determine the susceptibility of the pathogen strains to various currently available antimicrobial agents. MATERIALS AND METHODS: The diseased fishes were observed for variable clinical signs including fin hemorrhages, alterations in behavior associated with erratic swimming, exophthalmia, and mortality...
January 2017: Veterinary World
https://www.readbyqxmd.com/read/28243986/transcriptional-regulator-gntr-of-brucella-abortus-regulates-cytotoxicity-induces-the-secretion-of-inflammatory-cytokines-and-affects-expression-of-the-type-iv-secretion-system-and-quorum-sensing-system-in-macrophages
#17
Zhiqiang Li, Shuli Wang, Hui Zhang, Jinliang Zhang, Li Xi, Junbo Zhang, Chuangfu Chen
The pathogenic mechanisms of Brucella are still poorly understood. GntR is a transcriptional regulator and plays an important role in the intracellular survival of Brucella. To investigate whether GntR is involved in the cytotoxicity of Brucella abortus (B. abortus), we created a 2308ΔgntR mutant of B. abortus 2308 (S2308). Lactate dehydrogenase (LDH) cytotoxicity assays using a murine macrophage cell line (RAW 264.7) show that high-dose infection with the parental strain produces a high level of cytotoxicity to macrophages, but the 2308ΔgntR mutant exhibits a very low level of cytotoxicity, indicating that mutation of GntR impairs the cytotoxicity of B...
March 2017: World Journal of Microbiology & Biotechnology
https://www.readbyqxmd.com/read/28239476/prolonged-direct-hemoperfusion-using-a-polymyxin-b-immobilized-fiber-cartridge-provides-sustained-circulatory-stabilization-in-patients-with-septic-shock-a-retrospective-observational-before-after-study
#18
Kyohei Miyamoto, Yu Kawazoe, Seiya Kato
BACKGROUND: Direct hemoperfusion therapy with polymyxin B immobilized fiber cartridges (PMX-DHP) is widely used for septic shock in Japan and parts of Europe. Although this treatment is usually administered for 2 h, the optimal duration has not been established. METHODS: This retrospective study compared the effects of prolonged and conventional PMX-DHP durations (2 and 12 h, respectively) for septic shock. Between October 2013 and March 2015, 18 patients underwent conventional PMX-DHP, and between April 2015 and May 2016, 18 patients underwent prolonged PMX-DHP...
2017: Journal of Intensive Care
https://www.readbyqxmd.com/read/28180225/rediscovering-the-octapeptins
#19
REVIEW
Tony Velkov, Kade D Roberts, Jian Li
Covering: 1975 up to the end of 2016The decline in the discovery and development of novel antibiotics has resulted in the emergence of bacteria that are resistant to almost all available antibiotics. Currently, polymyxin B and E (colistin) are being used as the last-line therapy against life-threatening infections, unfortunately resistance to polymyxins in both the community and hospital setting is becoming more common. Octapeptins are structurally related non-ribosomal lipopeptide antibiotics that do not exhibit cross-resistance with polymyxins and have a broader spectrum of activity that includes Gram-positive bacteria...
February 9, 2017: Natural Product Reports
https://www.readbyqxmd.com/read/28169850/american-contact-dermatitis-society-core-allergen-series-2017-update
#20
Peter C Schalock, Cory A Dunnick, Susan Nedorost, Bruce Brod, Erin Warshaw, Christen Mowad
The American Contact Dermatitis Society Core Allergen Series was introduced in 2012. After 4 years of use, changes in our recommended allergens are necessary. For the updated series, we have reordered the first 4 panels to approximately mirror the current TRUE Test and removed parthenolide, triclosan, glutaraldehyde, and jasmine. Polymyxin B, lavender, sodium benzoate, ethylhexylglycerin, and benzoic acid are new additions to the American Contact Dermatitis Society series.
March 2017: Dermatitis
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