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antibiotic residues

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https://www.readbyqxmd.com/read/28535485/quantification-of-residual-antibiotics-in-cow-manure-being-spread-over-agricultural-land-and-assessment-of-their-behavioral-effects-on-antibiotic-resistant-bacteria
#1
Ji-Ran Yeom, Soon-Uk Yoon, Chang-Gyun Kim
Antibiotic resistant bacteria (ARB) in livestock manure used as fertilizer and spread over agriculture land, may pose a threat to the health of humans. Considering this, the concentrations of tetracycline (TC), oxytetracycline (OTC), and sulfathiazole (STZ) in the surface soil were quantified using LC-MS. These antibiotics have been used in livestock and are found in fertilizer produced from livestock excretions. Species of ABR were identified using 16S rDNA. Soil samples were collected at depths of 0, 7, and 15 cm from farmland in Incheon (South Korea)...
May 16, 2017: Chemosphere
https://www.readbyqxmd.com/read/28533107/ehs-matrix-incubated-in-media-containing-penicillin-retains-sufficient-concentrations-of-antibiotic-to-inhibit-growth-of-susceptible-microorganisms
#2
Mark P Murphy, Dagmara A Niedziela, Orla M Keane
In studying the interaction between bacteria and host cells in vitro, the latter are frequently cultured on commercially available biotic matrices such as Matrigel® or Geltrex®. To avoid contamination, host cells are commonly grown in the presence of antibiotics. However, we present here the finding that cell culture on such a matrix in the presence of antibiotics interferes with the outcome of subsequent infection experiments by virtue of diminished bacterial survival. By comparing outcomes for penicillin-susceptible and resistant strains of Staphylococcus aureus, we show that residual penicillin remains in the matrix despite the antibiotics' withdrawal from culture...
May 19, 2017: Journal of Microbiological Methods
https://www.readbyqxmd.com/read/28529863/ceramic-biocomposites-as-biodegradable-antibiotic-carriers-in-the-treatment-of-bone-infections
#3
REVIEW
Jamie Ferguson, Michael Diefenbeck, Martin McNally
Local release of antibiotic has advantages in the treatment of chronic osteomyelitis and infected fractures. The adequacy of surgical debridement is still key to successful clearance of infection but local antibiotic carriers seem to afford greater success rates by targeting the residual organisms present after debridement and delivering much higher local antibiotic concentrations compared with systemic antibiotics alone. Biodegradable ceramic carriers can be used to fill osseous defects, which reduces the dead space and provides the potential for subsequent repair of the osseous defect as they dissolve away...
2017: J Bone Jt Infect
https://www.readbyqxmd.com/read/28522606/structural-analysis-of-the-dual-function-thioesterase-sav606-unravels-the-mechanism-of-michael-addition-of-glycine-to-an-%C3%AE-%C3%AE-unsaturated-thioester
#4
Taichi Chisuga, Akimasa Miyanaga, Fumitaka Kudo, Tadashi Eguchi
Thioesterases catalyze hydrolysis of acyl thioesters to release carboxylic acid or macrocyclization to produce the corresponding macrocycle in the biosynthesis of fatty acids, polyketides, or nonribosomal peptides. Recently, we reported that the thioesterase CmiS1 from Streptomyces sp. MJ635-86F5 catalyzes the Michael addition of glycine to an α,β-unsaturated fatty acyl thioester followed by thioester hydrolysis in the biosynthesis of the macrolactam antibiotic cremimycin. However, the molecular mechanisms of CmiS1-catalyzed reactions are unclear...
May 18, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28522372/effective-antimicrobial-activity-of-a-peptide-mutant-cbf-14-2-against-penicillin-resistant-bacteria-based-on-its-unnatural-amino-acids
#5
Wei Kang, Hanhan Liu, Lingman Ma, Mengxiao Wang, Shanshan Wei, Pengbo Sun, Meiling Jiang, Min Guo, Changlin Zhou, Jie Dou
Broad spectrum activities, a unique mode of actions and rare resistant variants make antimicrobial peptide (AMP) a potential alternative to antibiotics. However, AMPs still have limitations in clinical development due to their physiological stability, toxicity and manufacturing costs. Cbf-14, derived from cathelicidin-BF has been proven to be effective against drug-resistant bacteria. Herein, a series of Cbf-14 mutants were designed to overcome these limitations. Design strategies included substitutions of lysine (Lys) or leucine (Leu) with similar residues such as ornithine (Orn) and norleucine (Ile), which are unnatural amino acids, to generate AMPs with enhanced therapeutic potential...
May 15, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28522308/development-of-a-ssdna-aptamer-for-detection-of-residual-benzylpenicillin
#6
A-Young Lee, Na-Reum Ha, In-Pil Jung, Sang-Heon Kim, A-Ru Kim, Moon-Young Yoon
Antibiotics are useful for improving the living conditions of livestock. However, residual antibiotics induce several human diseases such as food-borne illness and infection of carbapenem-resistant Enterobacteriaceae (CRE). In this study, the identification of a benzylpenicillin-specific aptamer was selected by rGO-SELEX (reduced Graphene Oxide-Systematic Evolution of Ligands by EXponential enrichment). A random ssDNA library was incubated with rGO for adsorption and eluted with benzylpenicillin. As a result of the selection process, a DNA aptamer was found that specifically bound to benzylpenicillin with high binding affinity, Kd = 383...
May 15, 2017: Analytical Biochemistry
https://www.readbyqxmd.com/read/28515650/prevalence-and-comparing-of-some-microbiological-properties-somatic-cell-count-and-antibiotic-residue-of-organic-and-conventional-raw-milk-produced-in-turkey
#7
Bayram Ürkek, Mustafa Şengül, Tuba Erkaya, Vecihi Aksakal
The aim of this study was to investigate the effects of production systems and milk collection periods on the somatic cell count (SCC), some microbiological properties, total aerobic mesophilic bacteria (TAMB), coliform, Staphylococcus aureus (S. aureus), yeast and mould) and antibiotic residue of milk; in Turkey. Milk samples were collected from 9 conventional farms and 9 organic farms during one year time, at six different months (December 2013 to October 2014), and all farms were selected from the same geographical locations...
2017: Korean Journal for Food Science of Animal Resources
https://www.readbyqxmd.com/read/28511809/characterisation-of-the-selective-binding-of-antibiotics-vancomycin-and-teicoplanin-by-the-vans-receptor-regulating-type-a-vancomycin-resistance-in-the-enterococci
#8
C S Hughes, E Longo, M K Phillips-Jones, R Hussain
A-type resistance towards "last-line" glycopeptide antibiotic vancomycin in the leading hospital acquired infectious agent, the enterococci, is the most common in the UK. Resistance is regulated by the VanRASA two-component system, comprising the histidine sensor kinase VanSA and the partner response regulator VanRA. The nature of the activating ligand for VanSA has not been identified, therefore this work sought to identify and characterise ligand(s) for VanSA. In vitro approaches were used to screen the structural and activity effects of a range of potential ligands with purified VanSA protein...
May 13, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28508407/structural-conservation-of-the-pin-domain-active-site-across-all-domains-of-life
#9
REVIEW
M Senissar, M C Manav, D E Brodersen
The PIN (PilT N-terminus) domain is a compact RNA-binding protein domain present in all domains of life. This 120-residue domain consists of a central and parallel β sheet surrounded by α helices, which together organize 4-5 acidic residues in an active site that binds one or more divalent metal ions and in many cases has endoribonuclease activity. In bacteria and archaea, the PIN domain is primarily associated with toxin-antitoxin loci, consisting of a toxin (the PIN domain nuclease) and an antitoxin that inhibits the function of the toxin under normal growth conditions...
May 15, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28507124/thiophene-antibacterials-that-allosterically-stabilize-dna-cleavage-complexes-with-dna-gyrase
#10
Pan F Chan, Thomas Germe, Benjamin D Bax, Jianzhong Huang, Reema K Thalji, Eric Bacqué, Anna Checchia, Dongzhao Chen, Haifeng Cui, Xiao Ding, Karen Ingraham, Lynn McCloskey, Kaushik Raha, Velupillai Srikannathasan, Anthony Maxwell, Robert A Stavenger
A paucity of novel acting antibacterials is in development to treat the rising threat of antimicrobial resistance, particularly in Gram-negative hospital pathogens, which has led to renewed efforts in antibiotic drug discovery. Fluoroquinolones are broad-spectrum antibacterials that target DNA gyrase by stabilizing DNA-cleavage complexes, but their clinical utility has been compromised by resistance. We have identified a class of antibacterial thiophenes that target DNA gyrase with a unique mechanism of action and have activity against a range of bacterial pathogens, including strains resistant to fluoroquinolones...
May 15, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28504677/%C3%AE-lactone-formation-during-product-release-from-a-nonribosomal-peptide-synthetase
#11
Jason E Schaffer, Margaret R Reck, Neha K Prasad, Timothy A Wencewicz
Nonribosomal peptide synthetases (NRPSs) are multidomain modular biosynthetic assembly lines that polymerize amino acids into a myriad of biologically active nonribosomal peptides (NRPs). NRPS thioesterase (TE) domains employ diverse release strategies for off-loading thioester-tethered polymeric peptides from termination modules typically via hydrolysis, aminolysis, or cyclization to provide mature antibiotics as carboxylic acids/esters, amides, and lactams/lactones, respectively. Here we report the enzyme-catalyzed formation of a highly strained β-lactone ring during TE-mediated cyclization of a β-hydroxythioester to release the antibiotic obafluorin (Obi) from an NRPS assembly line...
May 15, 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28500969/oxidation-of-the-antibacterial-agent-norfloxacin-during-sodium-hypochlorite-disinfection-of-marine-culture-water
#12
Yuanyuan Zhang, Chuan Rong, Yanqun Song, Yinghui Wang, Jiying Pei, Xinying Tang, Ruijie Zhang, Kefu Yu
Chlorination disinfection and antibiotic addition are two universal processes of marine culture. The generation of disinfection byproducts (DBPs) is unavoidable. Antibiotic residue not only pollutes water but also acts as a precursor to the production of new DBPs. The fate of antibiotic norfloxacin (NOR) in chlorination disinfection was investigated. It was observed that NOR could be oxidized by disinfection agent sodium hypochlorite, but the oxidation rate varied considerably with the type of disinfected water...
May 7, 2017: Chemosphere
https://www.readbyqxmd.com/read/28500886/optimized-removal-of-oxytetracycline-and-cadmium-from-contaminated-waters-using-chemically-activated-and-pyrolyzed-biochars-from-forest-and-wood-processing-residues
#13
Aylin Aghababaei, Mohamed Chaker Ncibi, Mika Sillanpää
In the present investigation, the adsorptive removal of the antibiotic drug oxytetracycline (OTC) and toxic heavy metal cadmium (Cd) from aqueous solution was carried out using forest and wood-processing residues. Numerous biochars were prepared using different chemical agents (H3PO4, H2SO4, NaOH and KOH) and pyrolysis times and temperatures. Several elemental, chemical and structural characterizations were performed. The optimum conditions for pyrolysis to enable the production of biochars with well-developed porosity was 600°C for 1h, for both residues...
May 3, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28500042/carboxyl-analogue-of-mutacin-1140-a-scaffold-for-lead-antibacterial-discovery
#14
Jerome Escano, Akshaya Ravichandran, Bita Salamat, Leif Smith
Mutacin 1140 belongs to the epidermin group of lantibiotics. Epidermin class lantibiotics are ribosomally synthesized and post translationally modified antibiotics with potent activity against Gram-positive bacteria. In particular, this class is effective at targeting drug resistant Streptococcus pneumoniae, MRSA,Mycobacterium tuberculosis, and Clostridium difficile A C-terminal S-[(Z)-2-aminovinyl]-D-cysteine (AviCys) residue is derived from a decarboxylation of a terminal cysteine that is involved in one of the lanthionine ring formation...
May 12, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28499189/synthesis-biological-evaluation-and-molecular-modeling-study-of-new-1-2-4-triazole-or-1-3-4-thiadiazole-methylthio-derivatives-of-quinazolin-4-3h-one-as-dhfr-inhibitors
#15
Yomna I El-Gazzar, Hanan H Georgey, Shahenda M El-Messery, Heba A Ewida, Ghada S Hassan, Marwa M Raafat, Menna A Ewida, Hussein I El-Subbagh
A new series of 2-mercapto-quinazolin-4-one analogues was designed, synthesized and evaluated for their in vitro DHFR inhibition, antitumor and antimicrobial activity. Compound 17 proved to be the most active DHFR inhibitor with IC50 value of 0.01μM, eight fold more active than methotrexate (MTX). Compounds 16 and 24 showed antitumor activity against human Caco2 colon and MCF-7 breast tumor cell lines with IC50 values of 25.4 and 9.5μg/ml, respectively. Compounds 15, 20, 21 and 30 showed considerable activity against the Gram-positive bacteria Staphylococcus aureus while 24 and 30 proved active against Bacillus subtilis with a magnitude of potency comparable to the broad spectrum antibiotic Ciprofloxacin...
May 4, 2017: Bioorganic Chemistry
https://www.readbyqxmd.com/read/28489306/pipecolic-acid-hydroxylases-a-monophyletic-clade-among-cis-selective-bacterial-proline-hydroxylases-that-discriminates-l-proline
#16
Johanna Mattay, Wolfgang Hüttel
Proline hydroxylases are Fe(II)/2-oxoglutarate-dependent enzymes that hydroxylate L-proline and derivatives, such as L-pipecolic acid, the six-membered ring homologue of L proline. We have established that there is a distinct group of conserved bacterial enzymes that hydroxylate L-pipecolic acid and trans-3- and trans-4-methyl-L-proline, but virtually no L proline. This allows the organism to produce hydroxyproline congeners without hydroxylation of the physiologically omnipresent L-proline. In vitro conversions showed that the substrate spectrum of the pipecolic acid hydroxylases GetF (from a Streptomyces sp...
May 10, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28488849/solution-conformations-and-dynamics-of-substrate-bound-cytochrome-p450-mycg
#17
Drew R Tietz, Larissa M Podust, David H Sherman, Thomas C Pochapsky
MycG is a P450 monooxygenase that catalyzes the sequential hydroxylation and epoxidation of mycinamicin IV (M-IV), the last two steps in the biosynthesis of mycinamicin II, a macrolide antibiotic isolated from Micromonospora griseorubida. The crystal structure of MycG with M-IV bound was previously determined but showed the bound substrate in an orientation that did not rationalize the observed regiochemistry of M-IV hydroxylation. Nuclear magnetic resonance paramagnetic relaxation enhancements provided evidence of an orientation of M-IV in the MycG active site more compatible with the observed chemistry, but substrate-induced changes in the enzyme structure were not characterized...
May 16, 2017: Biochemistry
https://www.readbyqxmd.com/read/28488115/redesign-of-antifungal-polyene-glycosylation-engineered-biosynthesis-of-disaccharide-modified-npp
#18
Hye-Jin Kim, Seung-Hoon Kang, Si-Sun Choi, Eung-Soo Kim
Polyene macrolides such as nystatin A1 and amphotericin B have been known to be potent antifungal antibiotics for several decades. Because the therapeutic application of polyenes is restricted by severe side effects such as nephrotoxicity, various chemical and biological studies to modify the polyene structure have been conducted to develop less-toxic polyene antifungals. A newly discovered nystatin-like polyene compound NPP was shown to contain an aglycone that was identical to nystatin but harbored a unique di-sugar moiety, mycosaminyl-N-acetyl-glucosamine, which led to higher solubility and reduced hemolytic toxicity...
May 9, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28487432/deciphering-mcr-2-colistin-resistance
#19
Jian Sun, Yongchang Xu, Rongsui Gao, Jingxia Lin, Wenhui Wei, Swaminath Srinivas, Defeng Li, Run-Shi Yang, Xing-Ping Li, Xiao-Ping Liao, Ya-Hong Liu, Youjun Feng
Antibiotic resistance is a prevalent problem in public health worldwide. In general, the carbapenem β-lactam antibiotics are considered a final resort against lethal infections by multidrug-resistant bacteria. Colistin is a cationic polypeptide antibiotic and acts as the last line of defense for treatment of carbapenem-resistant bacteria. Very recently, a new plasmid-borne colistin resistance gene, mcr-2, was revealed soon after the discovery of the paradigm gene mcr-1, which has disseminated globally. However, the molecular mechanisms for MCR-2 colistin resistance are poorly understood...
May 9, 2017: MBio
https://www.readbyqxmd.com/read/28483966/the-synergistic-efficacy-of-aedes-aegypti-antimicrobial-peptide-cecropin-a2-and-tetracycline-against-pseudomonas-aeruginosa
#20
Zhaojun Zheng, Nagendran Tharmalingam, Qingzhong Liu, Elamparithi Jayamani, Wooseong Kim, Beth Burgwyn Fuchs, Rijun Zhang, Andreas Vilcinskas, Eleftherios Mylonakis
The increasing prevalence of antibiotic resistance has created an urgent need for alternative drugs with new mechanisms of action. Antimicrobial peptides (AMPs) are promising candidates that could address the spread of multidrug-resistant bacteria, either alone or in combination with conventional antibiotics. We studied the antimicrobial efficacy and bactericidal mechanism of cecropin A2, a 36-residue α-helical cationic peptide derived from Aedes aegypti cecropin A, focusing on the common pathogen Pseudomonas aeruginosa The peptide showed little hemolytic activity and toxicity towards mammalian cells and the minimum inhibitory concentration (MIC) against most clinical P...
May 8, 2017: Antimicrobial Agents and Chemotherapy
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