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Polymyxins

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https://www.readbyqxmd.com/read/28344161/cross-resistance-to-human-cationic-antimicrobial-peptides-and-to-polymyxins-mediated-by-the-plasmid-encoded-mcr-1
#1
Jan Dobias, Laurent Poirel, Patrice Nordmann
OBJECTIVES: To evaluate whether acquired resistance to cationic antimicrobial peptides (CAMP) group molecules, being normal components of the human immune system, may select co-resistance to antibiotic peptides such as polymyxins, considering they share the same mechanism of action. We aimed to evaluate strains producing the recently identified plasmid-encoded polymyxin resistance determinant MCR-1, which is a phosphoethanolamine transferase that modifies the lipopolysaccharide structure of Gram-negative bacteria...
March 23, 2017: Clinical Microbiology and Infection
https://www.readbyqxmd.com/read/28343078/development-and-validation-of-liquid-chromatography-tandem-mass-spectrometry-method-quantitative-determination-of-polymyxin-b1-polymyxin-b2-polymyxin-b3-and-isoleucine-polymyxin-b1-in-human-plasma-and-its-application-in-clinical-studies
#2
Kim H Hee, Yee K J Leaw, Jun L Ong, Lawrence S Lee
Polymyxin B (PB) is an antibiotic consisting of a cyclic heptapeptide and a tripeptide side chain used in treatment of infections caused by Gram-negative bacteria. Commercial formulations of PB contain multiple structurally related components with major constituents of PB1, PB2, PB3 and ile-PB1. To understand the pharmacokinetics of these major components, we have developed and validated a LC-MS/MS method to quantify PB1, PB2, PB3 and ile-PB1 in human plasma. PB was extracted from plasma by protein precipitation using trichloroacetic acid followed by chromatographic separation on Zorbax Bonus-RP column (100mm×2...
March 14, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28342805/phosphoethanolamine-addition-to-the-heptose-i-of-the-lipopolysaccharide-modifies-the-inner-core-structure-and-has-an-impact-on-the-binding-of-polymyxin-b-to-the-escherichia-coli-outer-membrane
#3
Javier Salazar, Mackarenna Alarcon, Jaime Huerta, Belén Navarro, Daniel Aguayo
Phosphoethanolamine (pEtN) decoration of E. coli Lipopolysaccharide (LPS) provides resistance to the antimicrobial Polymyxin B (PolB). While EptA and EptB enzymes catalyze the addition of pEtN to the Lipid A and Kdo (pEtN-Kdo-Lipid A), EptC catalyzes the pEtN addition to the Heptose I (pEtN-HeptI). In this study, we investigated the contribution of pEtN-HeptI to PolB resistance using eptA/eptB and eptC deficient E. coli K12 and its wild-type parent strains. These mutations were shown to decrease the antimicrobial activity of PolB on cells grown under pEtN-addition inducing conditions...
March 22, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28334005/multi-scale-model-of-drug-induced-adaptive-resistance-of-gram-negative-bacteria-to-polymyxin-b
#4
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
#5
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
#6
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/28321410/oxidative-stress-induced-by-polymyxin-e-is-involved-in-rapid-killing-of-paenibacillus-polymyxa
#7
Zhiliang Yu, Yuyi Zhu, Wangrong Qin, Jianhua Yin, Juanping Qiu
Historically, the colistin has been thought to kill bacteria through membrane lysis. Here, we present an alternative mechanism that colistin induces rapid Paenibacillus polymyxa death through reactive oxygen species production. This significantly augments our understanding of the mechanism of colistin action, which is critical knowledge toward the yield development of colistin in the future.
2017: BioMed Research International
https://www.readbyqxmd.com/read/28320720/moraxella-species-as-potential-sources-of-mcr-like-polymyxin-resistance-determinants
#8
Nicolas Kieffer, Patrice Nordmann, Laurent Poirel
Plasmid-mediated resistance to polymyxins mediated by the MCR-1/-2 determinants has been recently reported in Enterobacteriaceae worldwide. Using PCR-based and cloning strategies, a series of Moraxella species were screened for mcr-like genes. Moraxella spp. that are mainly animal pathogens but may also be human pathogens were identified as potential reservoirs of mcr-like genes.
March 20, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28316780/screening-for-fecal-carriage-of-mcr-producing-enterobacteriaceae-in-healthy-humans-and-primary-care-patients
#9
Katrin Zurfluh, Roger Stephan, Andreas Widmer, Laurent Poirel, Patrice Nordmann, Hans-Jakob Nüesch, Herbert Hächler, Magdalena Nüesch-Inderbinen
BACKGROUND: The extent of the occurrence of the plasmid-encoded colistin resistance genes mcr-1 and mcr-2 among humans is currently sparsely studied in Western Europe. OBJECTIVES: To determine the occurrence of MCR-producing Enterobacteriaceae in fecal samples of healthy humans with high occupational exposure to food and primary care patients in Switzerland. METHODS: Stool samples from 1091 healthy individuals and fecal swabs from 53 primary care patients were screened for polymyxin-resistant Enterobacteriaceae using LB agar containing 4 mg/L colistin...
2017: Antimicrobial Resistance and Infection Control
https://www.readbyqxmd.com/read/28316480/inducible-spy-transcription-acts-as-a-sensor-for-envelope-stress-of-salmonella-typhimurium
#10
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
#11
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
#12
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
#13
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
#14
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/28293865/the-inhibition-effect-of-lactobacilli-against-growth-and-biofilm-formation-of-pseudomonas-aeruginosa
#15
Dariush Shokri, Mohammad Rabbani Khorasgani, Milad Mohkam, Seyed Masih Fatemi, Younes Ghasemi, Asghar Taheri-Kafrani
The emergence of antibiotic-resistant and food-spoilage microorganisms has renewed efforts to identify safe and natural alternative agents of antibiotics such as probiotics. The aim of this study was the isolation of lactobacilli as potential probiotics from local dairy products with broad antibacterial and anti-biofilm activities against antibiotic-resistant strains of Pseudomonas aeruginosa and determination of their inhibition mechanism. Antibiotic susceptibility and classification of acquired resistance profiles of 80 P...
March 14, 2017: Probiotics and Antimicrobial Proteins
https://www.readbyqxmd.com/read/28293307/sensitivity-to-antimicrobial-drugs-of-pseudomonas-aeruginosa-extreme-resistant-strains-isolated-in-the-major-hospitals-of-central-kazakhstan
#16
Ilya S Azizov, Alyona V Lavrinenko, Ilya A Belyaev, Dmitry B Babenko, Natalya A Shambilova, Nelya M Bissenova
AIM: The article presents the current data on the sensitivity of the main 37 strains of eXtremaly Drugs Resistance (XDR) category to anti-pseudomonas drugs. MATERIAL AND METHODS: The strains were collected during the prospective multicenter study in large multidisciplinary hospitals of Central Kazakhstan. Susceptibility to antimicrobial drugs was carried out by disk method and the serial dilution method with the interpretation of the results according to EUCAST criteria...
March 15, 2017: Open Access Macedonian Journal of Medical Sciences
https://www.readbyqxmd.com/read/28291943/a-new-combination-of-a-pleuromutilin-derivative-and-doxycycline-for-treatment-of-multidrug-resistant-acinetobacter-baumannii
#17
Shajila Siricilla, Katsuhiko Mitachi, Junshu Yang, Shakiba Eslamimehr, Maddie R Lemieux, Bernd Meibohm, Yinduo Ji, Michio Kurosu
Multidrug-resistant (MDR) Acinetobacter baumannii is one of the most difficult Gram-negative bacteria to treat and eradicate. In a cell-based screening of pleuromutilin derivatives against a drug sensitive A. baumannii strain, new molecules (2-4) exhibit bacteriostatic activity with 3.13 μg/mL concentration and 1 shows bactericidal activity with an MBC of 6.25 μg/mL. The pleuromutilin derivative 1 displays strong synergistic effects with doxycycline in a wide range of concentrations. A 35/1 ratio of 1 and doxycycline (1-Dox 35/1) kills drug susceptible A...
March 22, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28280277/preparation-and-antimicrobial-evaluation-of-polyion-complex-pic-nanoparticles-loaded-with-polymyxin-b
#18
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/28276793/lack-of-polymyxin-resistance-among-carbapenemase-producing-enterobacteriaceae-in-a-university-hospital-in-china
#19
Xiaofei Jiang, Laurent Poirel, Patrice Nordmann
No abstract text is available yet for this article.
March 3, 2017: Infectious Diseases
https://www.readbyqxmd.com/read/28276116/epidemiology-of-bacterial-conjunctivitis-in-chinchillas-chinchilla-lanigera-49-cases-2005-to-2015
#20
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
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