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Antibiotics

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https://www.readbyqxmd.com/read/29789481/concepts-and-methods-to-access-novel-antibiotics-from-actinomycetes
#1
REVIEW
Joachim J Hug, Chantal D Bader, Maja Remškar, Katarina Cirnski, Rolf Müller
Actinomycetes have been proven to be an excellent source of secondary metabolites for more than half a century. Exhibiting various bioactivities, they provide valuable approved drugs in clinical use. Most microorganisms are still untapped in terms of their capacity to produce secondary metabolites, since only a small fraction can be cultured in the laboratory. Thus, improving cultivation techniques to extend the range of secondary metabolite producers accessible under laboratory conditions is an important first step in prospecting underexplored sources for the isolation of novel antibiotics...
May 22, 2018: Antibiotics
https://www.readbyqxmd.com/read/29772736/exploring-the-effect-of-phage-therapy-in-preventing-vibrio-anguillarum-infections-in-cod-and-turbot-larvae
#2
Nanna Rørbo, Anita Rønneseth, Panos G Kalatzis, Bastian Barker Rasmussen, Kirsten Engell-Sørensen, Hans Petter Kleppen, Heidrun Inger Wergeland, Lone Gram, Mathias Middelboe
The aquaculture industry is suffering from losses associated with bacterial infections by opportunistic pathogens. Vibrio anguillarum is one of the most important pathogens, causing vibriosis in fish and shellfish cultures leading to high mortalities and economic losses. Bacterial resistance to antibiotics and inefficient vaccination at the larval stage of fish emphasizes the need for novel approaches, and phage therapy for controlling Vibrio pathogens has gained interest in the past few years. In this study, we examined the potential of the broad-host-range phage KVP40 to control four different V...
May 16, 2018: Antibiotics
https://www.readbyqxmd.com/read/29757948/streptomyces-differentiation-in-liquid-cultures-as-a-trigger-of-secondary-metabolism
#3
REVIEW
Ángel Manteca, Paula Yagüe
Streptomyces is a diverse group of gram-positive microorganisms characterised by a complex developmental cycle. Streptomycetes produce a number of antibiotics and other bioactive compounds used in the clinic. Most screening campaigns looking for new bioactive molecules from actinomycetes have been performed empirically, e.g., without considering whether the bacteria are growing under the best developmental conditions for secondary metabolite production. These screening campaigns were extremely productive and discovered a number of new bioactive compounds during the so-called "golden age of antibiotics" (until the 1980s)...
May 14, 2018: Antibiotics
https://www.readbyqxmd.com/read/29734649/toxicological-assessment-of-a-lignin-core-nanoparticle-doped-with-silver-as-an-alternative-to-conventional-silver-core-nanoparticles
#4
Cassandra E Nix, Bryan J Harper, Cathryn G Conner, Alexander P Richter, Orlin D Velev, Stacey L Harper
Elevated levels of silver in the environment are anticipated with an increase in silver nanoparticle (AgNP) production and use in consumer products. To potentially reduce the burden of silver ion release from conventional solid core AgNPs, a lignin-core particle doped with silver ions and surface-stabilized with a polycationic electrolyte layer was engineered. Our objective was to determine whether any of the formulation components elicit toxicological responses using embryonic zebrafish. Ionic silver and free surface stabilizer were the most toxic constituents, although when associated separately or together with the lignin core particles, the toxicity of the formulations decreased significantly...
May 4, 2018: Antibiotics
https://www.readbyqxmd.com/read/29724001/unraveling-nutritional-regulation-of-tacrolimus-biosynthesis-in-streptomyces-tsukubaensis-through-omic-approaches
#5
REVIEW
María Ordóñez-Robles, Fernando Santos-Beneit, Juan F Martín
Streptomyces tsukubaensis stands out among actinomycetes by its ability to produce the immunosuppressant tacrolimus. Discovered about 30 years ago, this macrolide is widely used as immunosuppressant in current clinics. Other potential applications for the treatment of cancer and as neuroprotective agent have been proposed in the last years. In this review we introduce the discovery of S. tsukubaensis and tacrolimus, its biosynthetic pathway and gene cluster ( fkb ) regulation. We have focused this work on the omic studies performed in this species in order to understand tacrolimus production...
May 1, 2018: Antibiotics
https://www.readbyqxmd.com/read/29693642/antibiotic-prescribing-for-oro-facial-infections-in-the-paediatric-outpatient-a-review
#6
REVIEW
Najla Dar-Odeh, Hani T Fadel, Shaden Abu-Hammad, Rua'a Abdeljawad, Osama A Abu-Hammad
There are many reports on the complications associated with antibiotics abuse during the treatment of paediatric patients, particularly those related to antimicrobial resistance. The dental profession is no exception; there is growing evidence that dental practitioners are misusing antibiotics in the treatment of their paediatric patients. This review is directed to dental practitioners who provide oral healthcare to children. It is also directed to medical practitioners, particularly those working in emergency departments and encountering children with acute orofacial infections...
April 25, 2018: Antibiotics
https://www.readbyqxmd.com/read/29693603/comparison-of-staphylococcus-phage-k-with-close-phage-relatives-commonly-employed-in-phage-therapeutics
#7
Jude Ajuebor, Colin Buttimer, Sara Arroyo-Moreno, Nina Chanishvili, Emma M Gabriel, Jim O'Mahony, Olivia McAuliffe, Horst Neve, Charles Franz, Aidan Coffey
The increase in antibiotic resistance in pathogenic bacteria is a public health danger requiring alternative treatment options, and this has led to renewed interest in phage therapy. In this respect, we describe the distinct host ranges of Staphylococcus phage K, and two other K-like phages against 23 isolates, including 21 methicillin-resistant S. aureus (MRSA) representative sequence types representing the Irish National MRSA Reference Laboratory collection. The two K-like phages were isolated from the Fersisi therapeutic phage mix from the Tbilisi Eliava Institute, and were designated B1 (vB_SauM_B1) and JA1 (vB_SauM_JA1)...
April 25, 2018: Antibiotics
https://www.readbyqxmd.com/read/29693566/specificity-of-induction-of-glycopeptide-antibiotic-resistance-in-the-producing-actinomycetes
#8
Elisa Binda, Pamela Cappelletti, Flavia Marinelli, Giorgia Letizia Marcone
Glycopeptide antibiotics are drugs of last resort for treating severe infections caused by Gram-positive pathogens. It is widely believed that glycopeptide-resistance determinants ( van genes) are ultimately derived from the producing actinomycetes. We hereby investigated the relationship between the antimicrobial activity of vancomycin and teicoplanins and their differential ability to induce van gene expression in Actinoplanes teichomyceticus —the producer of teicoplanin—and Nonomuraea gerenzanensis —the producer of the teicoplanin-like A40926...
April 25, 2018: Antibiotics
https://www.readbyqxmd.com/read/29690620/silk-route-to-the-acceptance-and-re-implementation-of-bacteriophage-therapy-part-ii
#9
Wilbert Sybesma, Christine Rohde, Pavol Bardy, Jean-Paul Pirnay, Ian Cooper, Jonathan Caplin, Nina Chanishvili, Aidan Coffey, Daniel De Vos, Amber Hartman Scholz, Shawna McCallin, Hilke Marie Püschner, Roman Pantucek, Rustam Aminov, Jiří Doškař, D İpek Kurtbӧke
This perspective paper follows up on earlier communications on bacteriophage therapy that we wrote as a multidisciplinary and intercontinental expert-panel when we first met at a bacteriophage conference hosted by the Eliava Institute in Tbilisi, Georgia in 2015. In the context of a society that is confronted with an ever-increasing number of antibiotic-resistant bacteria, we build on the previously made recommendations and specifically address how the Nagoya Protocol might impact the further development of bacteriophage therapy...
April 23, 2018: Antibiotics
https://www.readbyqxmd.com/read/29670064/veterinary-students-knowledge-and-perceptions-about-antimicrobial-stewardship-and-biosecurity-a-national-survey
#10
Laura Hardefeldt, Torben Nielsen, Helen Crabb, James Gilkerson, Richard Squires, Jane Heller, Claire Sharp, Rowland Cobbold, Jacqueline Norris, Glenn Browning
A better understanding of veterinary students’ perceptions, attitudes, and knowledge about antimicrobial stewardship and biosecurity could facilitate more effective education of future veterinarians about these important issues. A multicenter cross-sectional study was performed by administering a questionnaire to veterinary students expected to graduate in 2017 or 2018 in all Australian veterinary schools. Four hundred and seventy-six of 1246 students (38%) completed the survey. Many students were unaware of the high importance of some veterinary drugs to human medicine, specifically enrofloxacin and cefovecin (59% and 47% of responses, respectively)...
April 18, 2018: Antibiotics
https://www.readbyqxmd.com/read/29661993/the-cellular-mechanisms-that-ensure-an-efficient-secretion-in-streptomyces
#11
REVIEW
Sonia Gullón, Rafael P Mellado
Gram-positive soil bacteria included in the genus Streptomyces produce a large variety of secondary metabolites in addition to extracellular hydrolytic enzymes. From the industrial and commercial viewpoints, the S. lividans strain has generated greater interest as a host bacterium for the overproduction of homologous and heterologous hydrolytic enzymes as an industrial application, which has considerably increased scientific interest in the characterization of secretion routes in this bacterium. This review will focus on the secretion machinery in S...
April 14, 2018: Antibiotics
https://www.readbyqxmd.com/read/29642475/our-evolving-understanding-of-the-mechanism-of-quinolones
#12
REVIEW
Arnaud Gutierrez, Jonathan M Stokes, Ivan Matic
The maintenance of DNA supercoiling is essential for the proper regulation of a plethora of biological processes. As a consequence of this mode of regulation, ahead of the replication fork, DNA replication machinery is prone to introducing supercoiled regions into the DNA double helix. Resolution of DNA supercoiling is essential to maintain DNA replication rates that are amenable to life. This resolution is handled by evolutionarily conserved enzymes known as topoisomerases. The activity of topoisomerases is essential, and therefore constitutes a prime candidate for targeting by antibiotics...
April 8, 2018: Antibiotics
https://www.readbyqxmd.com/read/29621200/complementation-studies-of-bacteriophage-%C3%AE-o-amber-mutants-by-allelic-forms-of-o-expressed-from-plasmid-and-o-p-interaction-phenotypes
#13
Sidney Hayes, Karthic Rajamanickam, Connie Hayes
λ genes O and P are required for replication initiation from the bacteriophage λ origin site, ori λ, located within gene O . Questions have persisted for years about whether O-defects can indeed be complemented in trans . We show the effect of original null mutations in O and the influence of four origin mutations (three are in-frame deletions and one is a point mutation) on complementation. This is the first demonstration that O proteins with internal deletions can complement for O activity, and that expression of the N-terminal portion of gene P can completely prevent O complementation...
April 5, 2018: Antibiotics
https://www.readbyqxmd.com/read/29621136/complex-regulatory-networks-governing-production-of-the-glycopeptide-a40926
#14
REVIEW
Rosa Alduina, Margherita Sosio, Stefano Donadio
Glycopeptides (GPAs) are an important class of antibiotics, with vancomycin and teicoplanin being used in the last 40 years as drugs of last resort to treat infections caused by Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus . A few new GPAs have since reached the market. One of them is dalbavancin, a derivative of A40926 produced by the actinomycete Nonomuraea sp. ATCC 39727, recently classified as N. gerenzanensis . This review summarizes what we currently know on the multilevel regulatory processes governing production of the glycopeptide A40926 and the different approaches used to increase antibiotic yields...
April 5, 2018: Antibiotics
https://www.readbyqxmd.com/read/29565804/engineering-of-phage-derived-lytic-enzymes-improving-their-potential-as-antimicrobials
#15
REVIEW
Carlos São-José
Lytic enzymes encoded by bacteriophages have been intensively explored as alternative agents for combating bacterial pathogens in different contexts. The antibacterial character of these enzymes (enzybiotics) results from their degrading activity towards peptidoglycan, an essential component of the bacterial cell wall. In fact, phage lytic products have the capacity to kill target bacteria when added exogenously in the form of recombinant proteins. However, there is also growing recognition that the natural bactericidal activity of these agents can, and sometimes needs to be, substantially improved through manipulation of their functional domains or by equipping them with new functions...
March 22, 2018: Antibiotics
https://www.readbyqxmd.com/read/29565274/isolation-characterization-and-antibacterial-activity-of-hard-to-culture-actinobacteria-from-cave-moonmilk-deposits
#16
Delphine Adam, Marta Maciejewska, Aymeric Naômé, Loïc Martinet, Wouter Coppieters, Latifa Karim, Denis Baurain, Sébastien Rigali
Cave moonmilk deposits host an abundant and diverse actinobacterial population that has a great potential for producing novel natural bioactive compounds. In our previous attempt to isolate culturable moonmilk-dwelling Actinobacteria, only Streptomyces species were recovered, whereas a metagenetic study of the same deposits revealed a complex actinobacterial community including 46 actinobacterial genera in addition to streptomycetes. In this work, we applied the rehydration-centrifugation method to lessen the occurrence of filamentous species and tested a series of strategies to achieve the isolation of hard-to-culture and rare Actinobacteria from the moonmilk deposits of the cave "Grotte des Collemboles"...
March 22, 2018: Antibiotics
https://www.readbyqxmd.com/read/29561792/high-throughput-sequencing-analysis-of-the-actinobacterial-spatial-diversity-in-moonmilk-deposits
#17
Marta Maciejewska, Magdalena Całusińska, Luc Cornet, Delphine Adam, Igor S Pessi, Sandrine Malchair, Philippe Delfosse, Denis Baurain, Hazel A Barton, Monique Carnol, Sébastien Rigali
Moonmilk are cave carbonate deposits that host a rich microbiome, including antibiotic-producing Actinobacteria, making these speleothems appealing for bioprospecting. Here, we investigated the taxonomic profile of the actinobacterial community of three moonmilk deposits of the cave "Grotte des Collemboles" via high-throughput sequencing of 16S rRNA amplicons. Actinobacteria was the most common phylum after Proteobacteria, ranging from 9% to 23% of the total bacterial population. Next to actinobacterial operational taxonomic units (OTUs) attributed to uncultured organisms at the genus level (~44%), we identified 47 actinobacterial genera with Rhodoccocus (4 OTUs, 17%) and Pseudonocardia (9 OTUs, ~16%) as the most abundant in terms of the absolute number of sequences...
March 21, 2018: Antibiotics
https://www.readbyqxmd.com/read/29558417/geographic-variation-in-antibiotic-consumption-is-it-due-to-doctors-prescribing-or-patients-consulting
#18
Marte Meyer Walle-Hansen, Sigurd Høye
Antibiotic consumption varies greatly between Norwegian municipalities. We examine whether this variation is associated with inhabitants' consultation rates or general practitioners' (GP) prescription rates. Our study comprises consultations and antibiotic prescriptions for respiratory tract infections (RTIs) in general practice in all Norwegian municipalities with over 5000 inhabitants in 2014. Data was collected from The Norwegian Prescription Database, The Directorate of Health's system for control and payment of health reimbursements registry and Norway Statistics...
March 20, 2018: Antibiotics
https://www.readbyqxmd.com/read/29562650/novel-aspects-of-polynucleotide-phosphorylase-function-in-streptomyces
#19
REVIEW
George H Jones
Polynucleotide phosphorylase (PNPase) is a 3'-5'-exoribnuclease that is found in most bacteria and in some eukaryotic organelles. The enzyme plays a key role in RNA decay in these systems. PNPase structure and function have been studied extensively in Escherichia coli , but there are several important aspects of PNPase function in Streptomyces that differ from what is observed in E. coli and other bacterial genera. This review highlights several of those differences: (1) the organization and expression of the PNPase gene in Streptomyces ; (2) the possible function of PNPase as an RNA 3'-polyribonucleotide polymerase in Streptomyces ; (3) the function of PNPase as both an exoribonuclease and as an RNA 3'-polyribonucleotide polymerase in Streptomyces ; (4) the function of (p)ppGpp as a PNPase effector in Streptomyces ...
March 18, 2018: Antibiotics
https://www.readbyqxmd.com/read/29562616/parallel-colorimetric-quantification-of-choline-and-phosphocholine-as-a-method-for-studying-choline-kinase-activity-in-complex-mixtures
#20
Tahl Zimmerman, Salam A Ibrahim
Choline kinase (Chok) is an enzyme found in eukaryotes and Gram-positive bacteria. Chok catalyzes the production of phosphocholine from choline and ATP. This enzyme has been validated as a drug target in Streptococcus pneumonia , but the role Chok enzymatic activity plays in bacterial cell growth and division is not well understood. Phosphocholine production by Chok and its attenuation by inhibitors in the context of complex samples such as cell extracts can currently be quantified by several methods. These include choline depletion measurements, radioactive methods, mass-spectrometry, and nuclear magnetic resonance...
March 17, 2018: Antibiotics
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