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https://www.readbyqxmd.com/read/28932951/structure-elucidation-and-in-silico-docking-studies-of-a-novel-furopyrimidine-antibiotics-synthesized-by-endolithic-bacterium-actinomadura-sp-al2
#1
Kaushik Bhattacharjee, Shakti Kumar, Narasinga Rao Palepu, Pradeep Kumar Patra, Kollipara Mohan Rao, Santa Ram Joshi
On screening of endolithic actinobacteria from a granite rock sample of Meghalaya for antibacterial compound, a novel antibacterial compound CCp1 was isolated from the fermentation broth of Actinomadura sp. AL2. On purification of the compound based on chromatographic techniques followed by characterization with FT-IR, UV-visible, (1)H NMR, (13)C NMR and mass spectrometry, the molecular formula of the compound was generated as C20H17N3O2, a furopyrimidine derivative. In vitro antibacterial activity of the compound was evaluated against both Gram positive and negative bacteria by agar well diffusion assay...
September 20, 2017: World Journal of Microbiology & Biotechnology
https://www.readbyqxmd.com/read/28932329/molecular-characterization-of-klebsiella-pneumoniae-clinical-isolates-with-elevated-resistance-to-carbapenems
#2
Rasha Barwa, Mona Shaaban
BACKGROUND: Emergence of carbapenems-resistant K. pneumoniae represents a serious challenge for antimicrobial therapy. OBJECTIVE: The aim of this research is to determine different mechanisms mediating the emergence of K. pneumoniae isolates with high-level carbapenem resistance. METHOD: A total of 80 K. pneumoniae isolates were purified from sputum and urine specimens. The minimum inhibitory concentrations (MICs) of imipenem and meropenem were determined by broth microdilution method...
2017: Open Microbiology Journal
https://www.readbyqxmd.com/read/28930428/ion-transport-in-confined-geometries-below-the-nanoscale-access-resistance-dominates-protein-channel-conductance-in-diluted-solutions
#3
Antonio Alcaraz, M Lidón López, María Queralt-Martín, Vicente M Aguilella
Synthetic nanopores and mesoscopic protein channels have common traits like the importance of electrostatic interactions between the permeating ions and the nanochannel. Ion transport at the nanoscale occurs under confinement conditions so that the usual assumptions made in microfluidics are challenged, among others, by interfacial effects such as access resistance (AR). Here we show that a sound interpretation of electrophysiological measurements in terms of channel ion selective properties requires the consideration of interfacial effects, up to the point that they dominate protein channel conductance in diluted solutions...
September 20, 2017: ACS Nano
https://www.readbyqxmd.com/read/28919790/exploring-bacterial-outer-membrane-barrier-to-combat-bad-bugs
#4
REVIEW
Ishan Ghai, Shashank Ghai
One of the main fundamental mechanisms of antibiotic resistance in Gram-negative bacteria comprises an effective change in the membrane permeability to antibiotics. The Gram-negative bacterial complex cell envelope comprises an outer membrane that delimits the periplasm from the exterior environment. The outer membrane contains numerous protein channels, termed as porins or nanopores, which are mainly involved in the influx of hydrophilic compounds, including antibiotics. Bacterial adaptation to reduce influx through these outer membrane proteins (Omps) is one of the crucial mechanisms behind antibiotic resistance...
2017: Infection and Drug Resistance
https://www.readbyqxmd.com/read/28893647/coexistence-of-multidrug-resistance-mechanisms-and-virulence-genes-in-carbapenem-resistant-pseudomonas-aeruginosa-strains-from-a-tertiary-care-hospital-south-india
#5
Kalaiarasan Ellappan, Harish Belgode Narasimha, Saravana Kumar
BACKGROUND: This study aimed to identify the multiple drug resistance mechanisms and various virulence genes in high level carbapenem resistant P. aeruginosa (CARPA) isolates collected from patients hospitalized in a tertiary care hospital, South India. METHODOLOGY: A total of 156 CARPA isolates were included in this study. Multiplex PCR was optimized to detect carbapenemases and extended-spectrum beta-lactamase (ESBL) genes, respectively. Semi-quantitative reverse transcriptase PCR (RT-PCR) was optimized to evaluate OprD deficiency...
September 8, 2017: Journal of Global Antimicrobial Resistance
https://www.readbyqxmd.com/read/28890516/molecular-characterization-of-non-carbapenemase-producing-escherichia-coli-clinical-isolates-with-reduced-carbapenem-susceptibility-from-a-thai-university-hospital
#6
Sawitree Nuramrum, Aroonwadee Chanawong, Kamonwan Lunha, Aroonlug Lulitanond, Arunnee Sangka, Chotechana Wilailuckana, Sunpetch Angkititrakul, Nicha Charoensri, Lumyai Wonglakorn, Prajuab Chaimanee, Ploenchan Chetchotisakd
Twelve non-replicate carbapenemase-negative ertapenem-non-susceptible (CNENS) Escherichia coli isolates from a Thai university hospital between 2010 and 2014 were characterized and compared with two carbapenemase-producing E. coli isolates from the same hospital. Eight unique PFGE patterns were obtained. All produced CTX-M-15 β-lactamase and two isolates co-expressed either CMY-2 cephalosporinase or increased efflux pump. Amino acid sequence analysis revealed that OmpF defect (seven isolates) due to mutations generating premature proteins or an IS1 insertion was more prevalent than in OmpC (no truncated proteins found)...
September 11, 2017: Japanese Journal of Infectious Diseases
https://www.readbyqxmd.com/read/28888366/lipopolysaccharides-promote-binding-and-unfolding-of-the-antibacterial-colicin-e3-rrnase-domain
#7
Allan Mills, Franck Duong
Nuclease colicins are antibacterial proteins produced by certain strains of E. coli to reduce competition from rival strains. These colicins are generally organized with an N-terminal transport (T)-domain, a central receptor binding (R)-domain, and a C-terminal cytotoxic nuclease domain. These colicins are always produced in complex with an inhibitory immunity protein, which dissociates prior entrance of the cytotoxic domain in the target cell. How exactly colicins traverse the cell envelope is not understood, yet this knowledge is important for the design of new antibacterial therapies...
September 6, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28874410/identification-and-characterization-of-the-major-porin-of-desulfovibrio-vulgaris-hildenborough
#8
L Zeng, E Wooton, D A Stahl, P J Walian
Due in large part to their ability to facilitate the diffusion of a diverse range of solutes across the outer membrane (OM) of Gram-negative bacteria, the porins represent one of the most prominent and important bacterial membrane protein superfamilies. Notably, for the Gram-negative bacterium Desulfovibrio vulgaris Hildenborough (DvH), a model organism for studies of sulfate-reducing bacteria, no porins have been identified or proposed in its annotated genome. Results from initial biochemical studies suggested that the product of gene DVU0799, one of the most abundant proteins of the DvH OM and purified as a homotrimeric complex, was a strong porin candidate...
September 5, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28874380/the-global-regulatory-protein-crp-controls-multifactorial-fluoroquinolone-susceptibility-in-salmonella-enterica-serovar-typhimurium
#9
Stefani C Kary, Joshua R K Yoneda, Stephen C Olshefsky, Laura A Stewart, Steven B West, Andrew D S Cameron
Fluoroquinolone antibiotics are prescribed for the treatment of Salmonella enterica infections, but resistance to this family of antibiotics is growing. Here we report that loss of the global regulatory protein, CRP, or its allosteric effector, cAMP, reduces susceptibility to fluoroquinolones. A Δcrp mutation was synergistic with the primary fluoroquinolone resistance allele gyrA83, thus can contribute to clinically-relevant resistance. Decreased susceptibility to fluoroquinolones could be partly explained by decreased expression of the outer membrane porin genes ompA and ompF with a concomitant increase in the expression of the ciprofloxacin-resistance efflux pump gene acrB in Δcrp cells...
September 5, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28871245/comparative-genomic-analysis-of-neutrophilic-iron-ii-oxidizer-genomes-for-candidate-genes-in-extracellular-electron-transfer
#10
Shaomei He, Roman A Barco, David Emerson, Eric E Roden
Extracellular electron transfer (EET) is recognized as a key biochemical process in circumneutral pH Fe(II)-oxidizing bacteria (FeOB). In this study, we searched for candidate EET genes in 73 neutrophilic FeOB genomes, among which 43 genomes are complete or close-to-complete and the rest have estimated genome completeness ranging from 5 to 91%. These neutrophilic FeOB span members of the microaerophilic, anaerobic phototrophic, and anaerobic nitrate-reducing FeOB groups. We found that many microaerophilic and several anaerobic FeOB possess homologs of Cyc2, an outer membrane cytochrome c originally identified in Acidithiobacillus ferrooxidans...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28868304/treatment-of-sepsis-what-is-the-antibiotic-choice-in-bacteremia-due-to-carbapenem-resistant-enterobacteriaceae
#11
REVIEW
Fatema Alhashem, Nicolette Leonie Tiren-Verbeet, Emine Alp, Mehmet Doganay
Sepsis is one of the major challenges of today. Although gram-positive bacteria related infections are more prevalent in hospital setting, the highest mortality rate is associated with gram-negative microorganisms especially Enterobacteriaceae. Enterobacteriaceae, including Escherichia coli, Klebsiella spp., Proteus spp., Enterobacter spp. and Serratia spp. Resistance to β-lactams in Enterobacteriaceae is primarily attributed to the production of B-lactamase enzymes with subsequent antibiotic hydrolysis and to a lesser extent by alteration of efflux pump or porins expression...
August 16, 2017: World Journal of Clinical Cases
https://www.readbyqxmd.com/read/28861396/the-role-of-ompr-in-the-expression-of-genes-of-the-kdgr-regulon-involved-in-the-uptake-and-depolymerization-of-oligogalacturonides-in-yersinia-enterocolitica
#12
Marta Nieckarz, Adrianna Raczkowska, Karolina Jaworska, Ewa Stefańska, Karolina Skorek, Dorota Stosio, Katarzyna Brzostek
Oligogalacturonide (OGA)-specific porins of the KdgM family have previously been identified and characterized in enterobacterial plant pathogens. We found that deletion of the gene encoding response regulator OmpR causes the porin KdgM2 to become one of the most abundant proteins in the outer membrane of the human enteropathogen Yersinia enterocolitica. Reporter gene fusion and real-time PCR analysis confirmed that the expression of kdgM2 is repressed by OmpR. We also found that kdgM2 expression is subject to negative regulation by KdgR, a specific repressor of genes involved in the uptake and metabolism of pectin derivatives in plant pathogens...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28855980/pseudomonas-endocarditis-with-an-unstable-phenotype-the-challenges-of-isolate-characterization-and-carbapenem-stewardship-with-a-partial-review-of-the-literature
#13
Emil Lesho, Erik Snesrud, Yoon Kwak, Ana Ong, Rosslyn Maybank, Maryrose Laguio-Vila, Ann R Falsey, Mary Hinkle
BACKGROUND: Pseudomonas endocarditis is exceedingly rare, especially in patients without predisposing risks. We present such a case that included unexpected switches in antibacterial resistance profiles in two Pseudomonas aeruginosa (PA) strains with the same whole-genome sequence. The case also involved diagnostic and treatment challenges, such as issues with automated testing platforms, choosing the optimal aminoglycoside, minimizing unnecessary carbapenem exposure, and the need for faster, more informative laboratory tests...
2017: Antimicrobial Resistance and Infection Control
https://www.readbyqxmd.com/read/28854668/current-and-future-therapies-for-pseudomonas-aeruginosa-infection-in-patients-with-cystic-fibrosis
#14
Wynne D Smith, Emmanuelle Bardin, Loren Cameron, Claire L Edmondson, Katie V Farrant, Isaac Martin, Ronan A Murphy, Odel Soren, Andrew R Turnbull, Natasha Wierre-Gore, Eric W Alton, Jacob G Bundy, Andrew Bush, Gary J Connett, Saul N Faust, Alain Filloux, Paul S Freemont, Andrew L Jones, Zoltan Takats, Jeremy S Webb, Huw D Williams, Jane C Davies
Pseudomonas aeruginosa opportunistically infects the airways of patients with cystic fibrosis and causes significant morbidity and mortality. Initial infection can often be eradicated though requires prompt detection and adequate treatment. Intermittent and then chronic infection occurs in the majority of patients. Better detection of P. aeruginosa infection using biomarkers may enable more successful eradication before chronic infection is established. In chronic infection P. aeruginosa adapts to avoid immune clearance and resist antibiotics via efflux pumps, β-lactamase expression, reduced porins and switching to a biofilm lifestyle...
August 1, 2017: FEMS Microbiology Letters
https://www.readbyqxmd.com/read/28851220/biomimetic-strategy-to-reversibly-trigger-functionality-of-catalytic-nanocompartments-by-the-insertion-of-ph-responsive-biovalves
#15
Christoph Edlinger, Tomaz Einfalt, Mariana Spulber, Anja Car, Wolfgang Meier, Cornelia G Palivan
We describe an innovative strategy to generate catalytic compartments with triggered functionality at the nanoscale level by combining pH-reversible biovalves and enzyme-loaded synthetic compartments. The biovalve has been engineered by the attachment of stimuli-responsive peptides to a genetically modified channel porin, enabling a reversible change of the molecular flow through the pores of the porin in response to a pH change in the local environment. The biovalve functionality triggers the reaction inside the cavity of the enzyme-loaded compartments by switching the in situ activity of the enzymes on/off based on a reversible change of the permeability of the membrane, which blocks or allows the passage of substrates and products...
September 13, 2017: Nano Letters
https://www.readbyqxmd.com/read/28845995/functional-characterization-of-cell-free-expressed-oprf-porin-from-pseudomonas-aeruginosa-stably-incorporated-in-tethered-lipid-bilayers
#16
Marco Maccarini, Landry Gayet, Jean-Pierre Alcaraz, Lavinia Liguori, Barry Stidder, Erik B Watkins, Jean-Luc Lenormand, Donald K Martin
OprF has a central role in Pseudomonas aeruginosa virulence and thus provides a putative target for either vaccines or antibiotic cofactors that could overcome the bacterium's natural resistance to antibiotics. Here we describe a procedure to optimize the production of highly pure and functional OprF porins that are then incorporated into a tethered lipid bilayer. This is a stable biomimetic system that provides the capability to investigate structural aspects and function of OprF using and neutron reflectometry and electrical impedance spectroscopy...
September 12, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28839070/enhanced-water-permeability-and-tunable-ion-selectivity-in-subnanometer-carbon-nanotube-porins
#17
Ramya H Tunuguntla, Robert Y Henley, Yun-Chiao Yao, Tuan Anh Pham, Meni Wanunu, Aleksandr Noy
Fast water transport through carbon nanotube pores has raised the possibility to use them in the next generation of water treatment technologies. We report that water permeability in 0.8-nanometer-diameter carbon nanotube porins (CNTPs), which confine water down to a single-file chain, exceeds that of biological water transporters and of wider CNT pores by an order of magnitude. Intermolecular hydrogen-bond rearrangement, required for entry into the nanotube, dominates the energy barrier and can be manipulated to enhance water transport rates...
August 25, 2017: Science
https://www.readbyqxmd.com/read/28835595/identification-and-characterization-of-a-cell-wall-porin-from-gordonia-jacobaea
#18
Guadalupe Jiménez-Galisteo, Ester Fusté, Elisa Muñoz, Teresa Vinuesa, Tom G Villa, Roland Benz, Angel Domínguez, Miguel Viñas
Gordonia jacobaea is a bacterium belonging to the mycolata group characterized by its ability to produce carotenoids. Mycolic acids in the cell wall contribute to reducing the permeability of their envelopes requiring the presence of channel-forming proteins to allow the exchange of hydrophilic molecules with the surrounding medium. Identification and purification of the channel-forming proteins was accomplished by SDS-PAGE, Mass spectrometry and Mass peptide fingerprinting and the channel-forming activity was studied by reconstitution in lipid bilayers...
August 23, 2017: Journal of General and Applied Microbiology
https://www.readbyqxmd.com/read/28827415/antimicrobial-activity-of-ceftazidime-avibactam-tested-against-multidrug-resistant-enterobacteriaceae-and-pseudomonas-aeruginosa-isolates-from-united-states-medical-centers-2013-2016
#19
Helio S Sader, Mariana Castanheira, Dee Shortridge, Rodrigo E Mendes, Robert K Flamm
The in vitro activity of ceftazidime-avibactam and many comparator agents was determined against various resistant subsets of organisms selected among 36,380 Enterobacteriaceae and 7,868 Pseudomonas aeruginosa. Isolates were consecutively collected from 94 US hospitals, and all isolates were tested for susceptibility by reference broth microdilution methods in a central monitoring laboratory (JMI Laboratories). Enterobacteriaceae isolates resistant to carbapenems (CRE) and/or ceftazidime-avibactam (MIC ≥16 μg/mL) were evaluated for the presence of genes encoding ESBLs, KPC, NDM, and transferable AmpC enzymes...
August 21, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28826780/towards-a-peptide-based-vaccine-against-shigella-sonnei-a-subtractive-reverse-vaccinology-based-approach
#20
Shehneela Baseer, Sajjad Ahmad, Kara E Ranaghan, Syed Sikander Azam
Shigella sonnei is one of the major causes of shigellosis in technically advanced countries and reports of its unprecedented increase are published from the Middle East, Latin America, and Asia. The pathogen exhibits resistance against first and second line antibiotics which highlights the need for the development of an effective broad-spectrum vaccine. A computational based approach comprising subtractive reverse vaccinology was used for the identification of potential peptide-based vaccine candidates in the proteome of S...
August 18, 2017: Biologicals: Journal of the International Association of Biological Standardization
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