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Gram negative infection

Jamie L Burgess, R Alan Burgess, Yalemi Morales, Jenna M Bouvang, Sean J Johnson, Nicholas E Dickenson
Like many Gram-negative pathogens, Shigella rely on a complex type three secretion system (T3SS) to inject effector proteins into host cells, take over host functions, and ultimately establish infection. Despite these critical roles, the energetics and regulatory mechanisms controlling the T3SS and pathogen virulence remain largely unclear. In this study, we present a series of high-resolution crystal structures of Spa47 and use the structures to model an activated Spa47 oligomer, finding that ATP hydrolysis may be supported by specific sidechain contributions from adjacent protomers within the complex...
October 21, 2016: Journal of Biological Chemistry
Héloïse Coté, Marie-Anne Boucher, André Pichette, Benoit Roger, Jean Legault
ETHNOPHARMACOLOGICAL RELEVANCE: Oleoresin of Abies balsamea (L.) Mill. was used by Aboriginal people of the boreal forest of Canada and French Canadians to treat various infections, suggesting that oleoresin has antibacterial properties. AIM OF THE STUDY: In this study, the antibacterial activity of whole oleoresin from A. balsamea was investigated against E. coli, S. aureus and two methicillin-resistant S. aureus (MRSA) strains using a new sensitive assay developed to evaluate hydrophobic matrix and compounds...
October 18, 2016: Journal of Ethnopharmacology
Florian Graef, Branko Vukosavljevic, Jean-Philippe Michel, Marius Wirth, Oliver Ries, Chiara De Rossi, Maike Windbergs, Véronique Rosilio, Christian Ducho, Sarah Gordon, Claus-Michael Lehr
Gram-negative bacteria possess a unique and complex cell envelope, composed of an inner and outer membrane separated by an intermediate cell wall-containing periplasm. This tripartite structure acts intrinsically as a significant biological barrier, often limiting the permeation of anti-infectives, and so preventing such drugs from reaching their target. Furthermore, identification of the specific permeation-limiting envelope component proves difficult in the case of many anti-infectives, due to the challenges associated with isolation of individual cell envelope structures in bacterial culture...
October 18, 2016: Journal of Controlled Release: Official Journal of the Controlled Release Society
Matteo Bassetti, Alessia Carnelutti, Maddalena Peghin
The isolation of multi-drug-resistant gram-negative (MDRGN) pathogens has progressively increased worldwide and has been associated with important delays in the prescription of an adequate antibiotic treatment, resulting in increased mortality rates. Patient's stratification for MDRGN infections to optimize the prescription of an adequate empiric antimicrobial regimen is crucial. Areas covered: This article covers MDRGN epidemiology, with a specific focus on risk factors for harbouring infections sustained by extended-spectrum-Beta-lactamase (ESBL), carbapenem resistant Enterobacteriacae (CRE), MDR Pseudomonas aeruginosa and MDR Acinetobacter baumanii...
October 21, 2016: Expert Review of Anti-infective Therapy
Lesley J Scott
Intravenous ceftaroline fosamil (Zinforo™), a prodrug that is rapidly converted to its active metabolite ceftaroline, is approved for use in adults and children (from 2 months of age) with complicated skin and soft tissue infections (cSSTIs) or community-acquired pneumonia (CAP). In several multinational trials, ceftaroline fosamil was an effective and generally well tolerated treatment in adult and paediatric patients with cSSTIs or CAP. In the phase 3 CANVAS trials, ceftaroline fosamil treatment was noninferior to vancomycin plus aztreonam in adults with cSSTIs...
October 20, 2016: Drugs
R Fussen, S Lemmen
Multidrug resistant (MDR) bacteria present an increasing threat for intensive care patients. Whereas colonization of intensive care patients with methicillin-resistant staphylococcus aureus (MRSA) in German ICUs has remained at a constant level in recent years and therapeutic options have improved, colonization and infections with MDR gram-negative bacteria and vancomycin-resistant enterococci are increasing year by year. Only a few or even no therapeutic options remain for the treatment of these bacteria...
October 20, 2016: Medizinische Klinik, Intensivmedizin und Notfallmedizin
Barbara Maciejewska, Bartosz Roszniowski, Akbar Espaillat, Agata Kęsik-Szeloch, Grazyna Majkowska-Skrobek, Andrew M Kropinski, Yves Briers, Felipe Cava, Rob Lavigne, Zuzanna Drulis-Kawa
Lytic bacteriophages and phage-encoded endolysins (peptidoglycan hydrolases) provide a source for the development of novel antimicrobial strategies. In the present study, we focus on the closely related (96 % DNA sequence identity) environmental myoviruses vB_KpnM_KP15 (KP15) and vB_KpnM_KP27 (KP27) infecting multidrug-resistant Klebsiella pneumoniae and Klebsiella oxytoca strains. Their genome organisation and evolutionary relationship are compared to Enterobacter phage phiEap-3 and Klebsiella phages Matisse and Miro...
October 21, 2016: Applied Microbiology and Biotechnology
Karolina Niska, Narcyz Knap, Anna Kędzia, Maciej Jaskiewicz, Wojciech Kamysz, Iwona Inkielewicz-Stepniak
Objectives: In dentistry, silver nanoparticles (AgNPs) have drawn particular attention because of their wide antimicrobial activity spectrum. However, controversial information on AgNPs toxicity limited their use in oral infections. Therefore, the aim of the present study was to evaluate the antibacterial activities against a panel of oral pathogenic bacteria and bacterial biofilms together with potential cytotoxic effects on human gingival fibroblasts of 10 nm AgNPs: non-functionalized - uncapped (AgNPs-UC) as well as surface-functionalized with capping agent: lipoic acid (AgNPs-LA), polyethylene glycol (AgNPs-PEG) or tannic acid (AgNPs-TA) using silver nitrate (AgNO3) as control...
2016: International Journal of Medical Sciences
K Gopinath, S Kumaraguru, K Bhakyaraj, S Mohan, K S Venkatesh, M Esakkirajan, P R Kaleeswarran, S A Naiyf, S Kadaikunnan, M Govindarajan, G Benelli, A Arumugam
The green fabrication of metal nanoparticles using botanical extracts is gaining increasing research attention in nanotechnology, since it does not require high energy inputs or the production of highly toxic chemical byproducts. Here, silver (Ag), gold (Au) and their bimetallic (Ag/Au) nanoparticles (NPs) were green synthesized using the Gloriosa superba aqueous leaf extract. Metal NPs were studied by spectroscopic (UV-visible spectroscopy, fluorescence spectroscopy, FT-IR spectroscopy, XRD and EDX) and microscopic (AFM and TEM) analysis...
October 17, 2016: Microbial Pathogenesis
Weiwei Wang, Ting Jiang, Weihong Zhang, Chunyu Li, Jun Chen, Dandan Xiang, Kejiang Cao, Lian-Wen Qi, Ping Li, Wei Zhu, Wensen Chen, Yan Chen
The study was undertaken to describe the profile of patients and the characteristics of all multidrug-resistant gram-negative bacteria (MDR-GNB) and to assess mortality. We examined 138 patients with bloodstream infections (BSIs) caused by MDR-GNB. Clinical characteristics, antibiotic therapy, and in-hospital mortality were analyzed. Survivor and nonsurvivor subgroups were compared to identify predictors of mortality. The in-hospital mortality rate was 25.4%. Univariate analysis revealed that comorbidities and inadequate initial antimicrobial treatment could increase risk of death...
October 17, 2016: American Journal of Infection Control
Li Fang, Qiong Chen, Keren Shi, Xi Li, Qiucheng Shi, Fang He, Jiancang Zhou, Yunsong Yu, Xiaoting Hua
Klebsiella pneumoniae is a gram-negative bacterium that causes numerous diseases, including pneumonia and urinary tract infections. An increase in multidrug resistance has complicated the treatment of these bacterial infections, and although tigecycline shows activity against a broad spectrum of bacteria, resistant strains have emerged. In this study, the whole genomes of two clinical and six laboratory-evolved strains were sequenced to identify putative mutations related to tigecycline resistance. Of seven tigecycline-resistant strains, seven (100%) had ramR mutations, five (71...
2016: PloS One
Julia I Tandberg, Leidy X Lagos, Petter Langlete, Eva Berger, Anne-Lise Rishovd, Norbert Roos, Deepa Varkey, Ian T Paulsen, Hanne C Winther-Larsen
Membrane vesicles (MVs) are spherical particles naturally released from the membrane of Gram-negative bacteria. Bacterial MV production is associated with a range of phenotypes including biofilm formation, horizontal gene transfer, toxin delivery, modulation of host immune responses and virulence. This study reports comparative profiling of MVs from bacterial strains isolated from three widely disperse geographical areas. Mass spectrometry identified 119, 159 and 142 proteins in MVs from three different strains of Piscirickettsia salmonis isolated from salmonids in Chile (LF-89), Norway (NVI 5692) and Canada (NVI 5892), respectively...
2016: PloS One
Oscar Almarza, Katherine Valderrama, Manuel Ayala, Cristopher Segovia, Javier Santander
Piscirickettsia salmonis, a Gram-negative fastidious facultative intracellular pathogen, is the causative agent of the salmonid rickettsial septicemia (SRS). The P. salmonis iron acquisition mechanisms and its molecular regulation are unknown. Iron is an essential element for bacterial pathogenesis. Typically, genes that encode for the iron acquisition machinery are regulated by the ferric uptake regulator (Fur) protein. P. salmonis fur sequence database reveals a diversity of fur genes without functional verification...
March 2016: International Microbiology: the Official Journal of the Spanish Society for Microbiology
Pallavi Surase, Gita Nataraj, Sunil Kuyare, Preeti Mehta
OBJECTIVES: The study was carried out to determine the extent and type of contamination of the hands and accessories of staff from different settings and also to determine the phenotypic similarity between the isolates recovered from the same staff. DESIGN: Prospective cross-sectional study. SETTING: Tertiary care center. PARTICIPANTS: Health care workers (HCWs') and administrative staff. METHODS: Samples were collected and processed for bacteriology from the dominant hand, mobiles, aprons, stethoscopes and computer keyboards of 280 staff working in different settings after consent...
August 2016: Journal of the Association of Physicians of India
Saurabh Chaudhri, Alice A Thomas, Nasreen Samad, Stanley L Fan
AIM: To determine if patients with failing kidney transplants who opt to have peritoneal dialysis (PD) have poor short-term PD technique survival and increased rates of peritonitis. METHODS: We performed a retrospective analysis comparing 50 consecutive patients starting PD after a failed kidney transplant to 93 incident patients starting PD (matching for age, gender, diabetes causing renal failure, ethnicity and year of starting PD). RESULTS: The mean follow-up period was 26 months...
October 20, 2016: Nephrology
Ayse Ruveyda Ugur, Hatice Turk Dagi, Bahadir Ozturk, Gulsum Tekin, Duygu Findik
BACKGROUND: Methicillin resistance is a serious health concern since it has spread among Staphylococcus aureus and coagulase-negative Staphylococci (CoNS) that are frequent community and nosocomial pathogens worldwide. Methicillin-resistant strains are often resistant to other classes of antibiotics, making their treatment difficult. Nigella sativa oil is known to be active against Gram-positive cocci, yet its in vitro cytotoxicity is rarely investigated, is a proper and powerful candidate for treatment of methicillin-resistant isolates...
July 2016: Pharmacognosy Magazine
Aritreyee Datta, Vikas Yadav, Anirban Ghosh, Jaesun Choi, Dipita Bhattacharyya, Rajiv K Kar, Humaira Ilyas, Arkajyoti Dutta, Eunseol An, Jayanta Mukhopadhyay, Dongkuk Lee, Kaustuv Sanyal, Ayyalusamy Ramamoorthy, Anirban Bhunia
There is a significant need for developing compounds that kill Cryptococcus neoformans, the fungal pathogen that causes meningoencephalitis in immunocompromised individuals. Here, we report the mode of action of a designed antifungal peptide, VG16KRKP (VARGWKRKCPLFGKGG) against C. neoformans. It is shown that VG16KRKP kills fungal cells mainly through membrane compromise leading to efflux of ions and cell metabolites. Intracellular localization, inhibition of in vitro transcription, and DNA binding suggest a secondary mode of action for the peptide, hinting at possible intracellular targets...
October 18, 2016: Biophysical Journal
Kimberly F Starr, Eric A Porsch, Patrick C Seed, Christian Heiss, Radnaa Naran, L Scott Forsberg, Uri Amit, Pablo Yagupsky, Parastoo Azadi, Joseph W St Geme
Kingella kingae is an encapsulated gram-negative organism that is a common cause of osteoarticular infections in young children. In earlier work, we identified a glycosyltransferase gene called csaA that is necessary for synthesis of the [3)-β-GalpNAc-(1→5)-β-Kdop-(2→] polysaccharide capsule (type a) in K. kingae strain 269-492. In the current study, we analyzed a large collection of invasive and carrier isolates from Israel and found that csaA was present in only 47% of the isolates. Further examination of this collection using primers based on the sequence that flanks csaA revealed three additional gene clusters (designated the csb, csc, and csd loci), all encoding predicted glycosyltransferases...
October 2016: PLoS Pathogens
Jlenia Brunetti, Giulia Roscia, Ilaria Lampronti, Roberto Gambari, Leila Quercini, Chiara Falciani, Luisa Bracci, Alessandro Pini
The synthetic antimicrobial peptide SET-M33 has strong activity against bacterial infections due to Gram-negative bacteria. It is currently in preclinical development as a new drug to treat lung infections caused by Gram-negative bacteria. Here we report its strong anti-inflammatory activity in terms of reduced expression of a number of cytokines, enzymes and signal transduction factors involved in inflammation triggered by lipopolysaccharides (LPS) from P. aeruginosa, K. pneumoniae and E. coli. Sixteen cytokines and other major agents involved in inflammation were analyzed in macrophages and bronchial cells after stimulation with LPS and incubation with SET-M33...
October 7, 2016: Journal of Biological Chemistry
(no author information available yet)
Pseudomonas aeruginosa is the most common Gram-negative bacterium associated with nosocomial and life-threatening chronic infections in cystic fibrosis patients. This pathogen is well-known for its ability to attach to surfaces of indwelling medical devices to form biofilms, which consist of a regular array of extracellular polymers. Tenaciously bound to the surface of devices and inherently resilient to antibiotic treatment, P. aeruginosa poses a serious threat in clinical medicine and contributes to the persistence of chronic infections...
October 19, 2016: Current Drug Targets
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