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Polymyxin resistance

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https://www.readbyqxmd.com/read/28416554/in-vitro-study-of-isapl1-mediated-mobilization-of-the-colistin-resistance-gene-mcr-1
#1
Laurent Poirel, Nicolas Kieffer, Patrice Nordmann
The plasmid-mediated mcr-1 gene encodes a phosphoethanolamine transferase conferring resistance to polymyxins. The mcr-1 gene is associated with insertion sequence ISApl1 (IS30 family). In-vitro mobilization assays demonstrated the functionality of the composite transposon structure ISApl1-mcr-1-ISApl1 Transposition generated a 2-bp duplication and occurred in AT-rich DNA regions. This is the first report demonstrating the mobility of the mcr-1 gene by transposition.
April 17, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28416543/potential-toxicity-of-polymyxins-in-human-lung-epithelial-cells
#2
Maizbha U Ahmed, Tony Velkov, Yu-Wei Lin, Bo Yun, Cameron J Nowell, Fanfan Zhou, Qi Tony Zhou, Kim Chan, Mohammad A K Azad, Jian Li
Inhaled polymyxins are of considerable utility to achieve optimal exposure in the respiratory tract for the treatment of lung infections caused by multidrug-resistant Gram-negative pathogens. Current inhaled polymyxin therapy is empirical and often high doses are used which may lead to potential pulmonary adverse effects. This study aimed to investigate the effect of polymyxins on human lung epithelial cells (A549). Viability of A549 cells was examined after treatment with polymyxins using flow cytometry. Activation of caspase-3, -8, -9, expression of Fas ligand (FasL), loss of mitochondrial membrane potential and mitochondrial oxidative stress induced by polymyxin B was evaluated...
April 17, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28406770/frequency-and-antibiogram-of-isolates-from-surgical-units-of-a-tertiary-care-hospital-in-quetta
#3
Maria Mushtaq Gill, Muhammad Junaid Khan, Muhammad Asif Nawaz, Sarfraz Khan Janjua
OBJECTIVE: To determine the frequency and antibiogram of the isolates from infected patients in surgical units of a tertiary care hospital. STUDY DESIGN: Cross-sectional, descriptive study. PLACE AND DURATION OF STUDY: Department of Microbiology, Combined Military Hospital, Quetta, from March to October 2015. METHODOLOGY: Clinical samples from the surgical units received in Department of Microbiology for culture and sensitivity were analyzed by Gram stain, culture and biochemical tests for identification of the isolates; and the antibiotic susceptibility was determined by modified Kirby Bauer disc diffusion method...
March 2017: Journal of the College of Physicians and Surgeons—Pakistan: JCPSP
https://www.readbyqxmd.com/read/28396353/the-histidine-residue-of-qsec-is-required-for-canonical-signaling-between-qseb-and-pmrb-in-uropathogenic-escherichia-coli
#4
Erin J Breland, Ellisa W Zhang, Tomas Bermudez, Charles R Martinez, Maria Hadjifrangiskou
Two-component systems are prototypically comprised of a histidine kinase (sensor) and a response regulator (responder). The sensor kinases auto-phosphorylate at a conserved histidine residue, acting as a phospho-donor for subsequent phosphotransfer to and activation of a cognate response regulator. In rare cases, the histidine residue is also essential for response regulator de-phosphorylation via a reverse-phosphotransfer reaction. In this work, we present an example of a kinase that relies on reverse-phosphotransfer to catalyze the de-phosphorylation of its cognate partner...
April 10, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28394975/-risk-factors-for-acute-kidney-injury-in-patients-treated-with-polymyxin-b-experience-from-139-cases-at-a-tertiary-university-hospital-in-colombia
#5
Johanna Osorio, Jackeline Barreto, Claudia F Samboni, Lina A Cándelo, Luis C Álvarez, Susana Benavidez, Roso P Téllez, Dagoberto Santofimio, Jorge A Ramos, Carlos A Gómez
BACKGROUND: The rise of infections caused by multidrug-resistant Gram negative bacilli (MDR-GNB), added to paucity of newer therapy, have led to increase polymyxin B use, despite adverse renal toxicity profile. AIM: To determine the incidence and risk factors associated to acute kidney injury (AKI) and polymyxin B use, in patients with infections caused by MDR-GNB. METHODS: A retrospective cohort, with a nested case-control study of adults who received polymyxin B for more than 48 hours at a tertiary university hospital in Colombia (2011-2015) was performed...
February 2017: Revista Chilena de Infectología: órgano Oficial de la Sociedad Chilena de Infectología
https://www.readbyqxmd.com/read/28384882/polymyxin-b-induced-diffuse-cutaneous-hyperpigmentation
#6
Sandeep Lahiry, Shouvik Choudhury, Ayan Mukherjee, Prajesh Kiran Bhunya, Moumita Bala
Polymyxin B is a polypeptide-antibiotic, primarily used for resistant Gram-negative infections, first obtained from bacterium Bacillus polymyxa in the late 1940s. Antibiotic spectrum are restricted to mainly gram negative bacterias like Enterobacter, E. coli, Klebsiella, Salmonella, Pasteurella, Bordetella, Shigella; and particularly organisms like Pseudomonas aeruginosa and Acinetobacter baumannii, which are extremely potent to acquire antibiotic resistance. Side effects include neurotoxicity and acute renal tubular necrosis...
February 2017: Journal of Clinical and Diagnostic Research: JCDR
https://www.readbyqxmd.com/read/28367020/comparison-of-four-phenotypic-methods-for-detection-of-metallo-%C3%AE-lactamase-producing-gram-negative-bacteria-in-rural-teaching-hospital
#7
Chinjal A Panchal, Sweta Sunil Oza, Sanjay J Mehta
CONTEXT: Metallo-β-lactamase (MBL)-producing bacteria lead to resistance to carbapenem an antibiotic that used as the last resort for treatment of multidrug-resistant bacteria, extended spectrum beta-lactamases, and AmpC β-lactamase-producing Gram-negative bacteria (GNB). The emergence of MBL-producing GNB is challenge to microbiology laboratories because there are no standardized guidelines available to detect them. The aim of this study was to compare four phenotypic methods to detect MBL production in GNB and to determine antibiotic sensitivity of MBL-producing isolates...
April 2017: Journal of Laboratory Physicians
https://www.readbyqxmd.com/read/28351920/spxa1-and-spxa2-act-coordinately-to-fine-tune-stress-responses-and-virulence-in-streptococcus-pyogenes
#8
Gary C Port, Zachary T Cusumano, Paul R Tumminello, Michael G Caparon
SpxA is a unique transcriptional regulator highly conserved among members of the phylum Firmicutes that binds RNA polymerase and can act as an antiactivator. Why some Firmicutes members have two highly similar SpxA paralogs is not understood. Here, we show that the SpxA paralogs of the pathogen Streptococcus pyogenes, SpxA1 and SpxA2, act coordinately to regulate virulence by fine-tuning toxin expression and stress resistance. Construction and analysis of mutants revealed that SpxA1(-) mutants were defective for growth under aerobic conditions, while SpxA2(-) mutants had severely attenuated responses to multiple stresses, including thermal and oxidative stresses...
March 28, 2017: MBio
https://www.readbyqxmd.com/read/28344161/cross-resistance-to-human-cationic-antimicrobial-peptides-and-to-polymyxins-mediated-by-the-plasmid-encoded-mcr-1
#9
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/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
#10
Javier Salazar, Mackarenna Alarcón, 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...
April 15, 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
#11
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
#12
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/28320720/moraxella-species-as-potential-sources-of-mcr-like-polymyxin-resistance-determinants
#13
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
#14
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/28306723/the-redefinition-of-helicobacter-pylori-lipopolysaccharide-o-antigen-and-core-oligosaccharide-domains
#15
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 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28302074/clonality-outer-membrane-proteins-profile-and-efflux-pump-in-kpc-producing-enterobacter-sp-in-brazil
#16
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/28295668/dissemination-of-metallo-%C3%AE-lactamase-in-pseudomonas-aeruginosa-isolates-in-egypt-mutation-in-blavim-4
#17
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
#18
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
#19
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
#20
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
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