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Antibiotic Efflux

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https://www.readbyqxmd.com/read/28720734/lack-of-acrb-efflux-function-confers-loss-of-virulence-on-salmonella-enterica-serovar-typhimurium
#1
Xuan Wang-Kan, Jessica M A Blair, Barbara Chirullo, Jonathan Betts, Roberto M La Ragione, Alasdair Ivens, Vito Ricci, Timothy J Opperman, Laura J V Piddock
AcrAB-TolC is the paradigm resistance-nodulation-division (RND) multidrug resistance efflux system in Gram-negative bacteria, with AcrB being the pump protein in this complex. We constructed a nonfunctional AcrB mutant by replacing D408, a highly conserved residue essential for proton translocation. Western blotting confirmed that the AcrB D408A mutant had the same native level of expression of AcrB as the parental strain. The mutant had no growth deficiencies in rich or minimal medium. However, compared with wild-type SL1344, the mutant had increased accumulation of Hoechst 33342 dye and decreased efflux of ethidium bromide and was multidrug hypersusceptible...
July 18, 2017: MBio
https://www.readbyqxmd.com/read/28717309/molecular-characterization-of-antibiotic-resistant-staphylococcus-aureus-from-livestock-bovine-and-swine
#2
Asima Zehra, Randhir Singh, Simranpreet Kaur, J P S Gill
AIM: The aim of this study was to figure the prevalence, phenotypic and genotypic antibiotic resistance (AR) pattern of Staphylococcus aureus isolated from bovine and swine nares. MATERIALS AND METHODS: Colonies with typical morphology on Baird-Parker agar supplemented with egg-yolk tellurite emulsion were selected and biochemically/genotypically identified as S. aureus. These strains were further subjected to epsilometer test for their sensitivity to various clinically important antibiotics and antibiotic susceptibility testing for amoxicillin/clavulanic acid, and double-disk diffusion testing was performed by the standard disc diffusion method following CLSI guidelines...
June 2017: Veterinary World
https://www.readbyqxmd.com/read/28710521/efflux-drug-transporters-at-the-forefront-of-antimicrobial-resistance
#3
REVIEW
Tahmina Rahman, Benjamin Yarnall, Declan A Doyle
Bacterial antibiotic resistance is rapidly becoming a major world health consideration. To combat antibiotics, microorganisms employ their pre-existing defence mechanisms that existed long before man's discovery of antibiotics. Bacteria utilise levels of protection that range from gene upregulation, mutations, adaptive resistance, and production of resistant phenotypes (persisters) to communal behaviour, as in swarming and the ultimate defence of a biofilm. A major part of all of these responses involves the use of antibiotic efflux transporters...
July 14, 2017: European Biophysics Journal: EBJ
https://www.readbyqxmd.com/read/28709374/nanoparticles-as-efflux-pump-and-biofilm-inhibitor-to-rejuvenate-bactericidal-effect-of-conventional-antibiotics
#4
REVIEW
Divya Gupta, Ajeet Singh, Asad U Khan
The universal problem of bacterial resistance to antibiotic reflects a serious threat for physicians to control infections. Evolution in bacteria results in the development of various complex resistance mechanisms to neutralize the bactericidal effect of antibiotics, like drug amelioration, target modification, membrane permeability reduction, and drug extrusion through efflux pumps. Efflux pumps acquire a wide range of substrate specificity and also the tremendous efficacy for drug molecule extrusion outside bacterial cells...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28705986/draft-genome-sequence-of-multidrug-resistant-cellulosimicrobium-sp-strain-kwt-b-isolated-from-feces-of-hirundo-rustica
#5
Takehiko Kenzaka, Yuina Ishimoto, Katsuji Tani
Migratory birds have been postulated as potential spreaders of antibiotic resistance. Multidrug-resistant Cellulosimicrobium sp. strain KWT-B was isolated from the feces of Hirundo rustica A draft genome sequence indicated that the strain harbors multidrug-resistant transporters, multidrug efflux pumps, a vancomycin-resistant protein, and metallo-beta-lactamases.
July 13, 2017: Genome Announcements
https://www.readbyqxmd.com/read/28700746/antibacterial-small-molecules-targeting-the-conserved-toprim-domain-of-dna-gyrase
#6
Scott S Walker, Marc Labroli, Ronald E Painter, Judyann Wiltsie, Brad Sherborne, Nicholas Murgolo, Xinwei Sher, Paul Mann, Paul Zuck, Charles G Garlisi, Jing Su, Stacia Kargman, Li Xiao, Giovanna Scapin, Scott Salowe, Kristine Devito, Payal Sheth, Nichole Buist, Christopher M Tan, Todd A Black, Terry Roemer
To combat the threat of antibiotic-resistant Gram-negative bacteria, novel agents that circumvent established resistance mechanisms are urgently needed. Our approach was to focus first on identifying bioactive small molecules followed by chemical lead prioritization and target identification. Within this annotated library of bioactives, we identified a small molecule with activity against efflux-deficient Escherichia coli and other sensitized Gram-negatives. Further studies suggested that this compound inhibited DNA replication and selection for resistance identified mutations in a subunit of E...
2017: PloS One
https://www.readbyqxmd.com/read/28698674/insight-into-synergetic-mechanisms-of-tetracycline-and-the-selective-serotonin-reuptake-inhibitor-sertraline-in-a-tetracycline-resistant-strain-of-escherichia-coli
#7
Lili Li, Sofie Kromann, John Elmerdahl Olsen, Søren Wedel Svenningsen, Rikke Heidemann Olsen
Sertraline, an antidepressive drug, has been reported to inhibit general bacterial efflux pumps. In the present study, we report for the first time a synergistic effect of sertraline and tetracycline in a TetA-encoded tetracycline-resistant strain of Escherichia coli. Synergy between sertraline and tetracycline in an E. coli strain with TetA-mediated tetracycline resistance (E. coli APEC_O2) was assessed by the MIC and checkerboard assays. The global transcriptome of E. coli APEC_O2 exposed to ½ MIC concentrations of sertraline and/or tetracycline was analyzed to elucidate the interaction mechanism between sertraline and tetracycline...
July 12, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28695852/the-multidrug-resistance-transporter-mdfa-from-escherichia-coli-crystallization-and-x-ray-diffraction-analysis
#8
Kumar Nagarathinam, Frank Jaenecke, Yoshiko Nakada-Nakura, Yunhon Hotta, Kehong Liu, So Iwata, Milton T Stubbs, Norimichi Nomura, Mikio Tanabe
The active efflux of antibiotics by multidrug-resistance (MDR) transporters is a major pathway of drug resistance and complicates the clinical treatment of bacterial infections. MdfA is a member of the major facilitator superfamily (MFS) from Escherichia coli and provides resistance to a wide variety of dissimilar toxic compounds, including neutral, cationic and zwitterionic substances. The 12-transmembrane-helix MdfA was expressed as a GFP-octahistidine fusion protein with a TEV protease cleavage site. Following tag removal, MdfA was purified using two chromatographic steps, complexed with a Fab fragment and further purified using size-exclusion chromatography...
July 1, 2017: Acta Crystallographica. Section F, Structural Biology Communications
https://www.readbyqxmd.com/read/28689875/contribution-of-acrab-tolc-to-multidrug-resistance-in-an-escherichia-coli-sequence-type-131-isolate
#9
Sabine Schuster, Martina Vavra, Tobias Schweigger, John W A Rossen, Yasufumi Matsumura, Winfried V Kern
Drug efflux by resistance-nodulation-cell division (RND)-type transporters, such as AcrAB-TolC of Escherichia coli, is an important resistance mechanism in Gram-negative bacteria; however, its contribution to multidrug resistance (MDR) in clinical isolates is poorly defined. We inactivated acrB of a sequence type 131 E. coli human isolate that showed high-level MDR, but had no mutations within the known efflux-associated local or global regulators. The resistance profile of the acrB deletion mutant revealed significantly increased susceptibility to drugs from seven antibiotic classes, including agents usually inactive against Gram-negative bacteria, notably the new oxazolidinone, tedizolid (512-fold enhanced susceptibility)...
July 6, 2017: International Journal of Antimicrobial Agents
https://www.readbyqxmd.com/read/28663823/sequencing-a-piece-of-history-complete-genome-sequence-of-the-original-escherichia-coli-strain
#10
Karl A Dunne, Roy R Chaudhuri, Amanda E Rossiter, Irene Beriotto, Douglas F Browning, Derrick Squire, Adam F Cunningham, Jeffrey A Cole, Nicholas Loman, Ian R Henderson
In 1885, Theodor Escherich first described the Bacillus coli commune, which was subsequently renamed Escherichia coli. We report the complete genome sequence of this original strain (NCTC 86). The 5 144 392 bp circular chromosome encodes the genes for 4805 proteins, which include antigens, virulence factors, antimicrobial-resistance factors and secretion systems, of a commensal organism from the pre-antibiotic era. It is located in the E. coli A subgroup and is closely related to E. coli K-12 MG1655. E...
March 2017: Microbial Genomics
https://www.readbyqxmd.com/read/28662489/viable-but-non-culturable-e-%C3%A2-coli-induced-by-low-level-chlorination-have-higher-persistence-to-antibiotics-than-their-culturable-counterparts
#11
Huirong Lin, Chengsong Ye, Sheng Chen, Shenghua Zhang, Xin Yu
Disinfectant used in drinking water treatment and distribution system can induce culturable bacteria, including various kinds of pathogenic bacteria, into viable but non-culturable (VBNC) state. The loss of cultural state, resuscitation and environmental persistence of VBNC bacteria will severely damage drinking water microbiological safety and thus pose a risk to public health. The manner in which chlorination treatment induced a VBNC state in Escherichia coli and the antibiotic persistence of VBNC bacteria was investigated...
June 26, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28654368/evaluation-of-carbapenem-resistance-mechanisms-and-its-association-with-pseudomonas-aeruginosa-infections-in-the-northwest-of-iran
#12
Mohammad Taghi Akhi, Younes Khalili, Reza Ghotaslou, Saber Yousefi, Hossein Samadi Kafil, Behrooz Naghili, Vajihe Sheikhalizadeh
The aims of this study were to determine carbapenem resistance mechanisms, molecular epidemiological relationship, clinical impact, and patient outcome of carbapenem-resistant Pseudomonas aeruginosa (CRPA) infections. A total of 42 nonduplicated CRPA were recovered from Urmia, Iran. Antimicrobial susceptibility tests were carried out using phenotypic methods. The carbapenem resistance mechanisms such as carbapenemase genes, efflux pump hyperexpression, AmpC overproduction, and OprD gene downregulation were determined by phenotypic and molecular methods...
June 27, 2017: Microbial Drug Resistance: MDR: Mechanisms, Epidemiology, and Disease
https://www.readbyqxmd.com/read/28651019/in-silico-genomic-insights-into-aspects-of-food-safety-and-defense-mechanisms-of-a-potentially-probiotic-lactobacillus-pentosus-mp-10-isolated-from-brines-of-naturally-fermented-alore%C3%A3-a-green-table-olives
#13
Hikmate Abriouel, Beatriz Pérez Montoro, María Del Carmen Casado Muñoz, Charles W Knapp, Antonio Gálvez, Nabil Benomar
Lactobacillus pentosus MP-10, isolated from brines of naturally fermented Aloreña green table olives, exhibited high probiotic potential. The genome sequence of L. pentosus MP-10 is currently considered the largest genome among lactobacilli, highlighting the microorganism's ecological flexibility and adaptability. Here, we analyzed the complete genome sequence for the presence of acquired antibiotic resistance and virulence determinants to understand their defense mechanisms and explore its putative safety in food...
2017: PloS One
https://www.readbyqxmd.com/read/28650638/identification-and-structure-activity-relationships-of-novel-compounds-that-potentiate-the-activities-of-antibiotics-in-escherichia-coli
#14
Keith M Haynes, Narges Abdali, Varsha Jhawar, Helen I Zgurskaya, Jerry M Parks, Adam T Green, Jerome Yves Baudry, Valentin V Rybenkov, Jeremy C Smith, John K Walker
In Gram-negative bacteria, efflux pumps are able to prevent effective cellular concentrations from being achieved for a number of antibiotics. Small molecule adjuvants that act as efflux pump inhibitors (EPIs) have the potential to reinvigorate existing antibiotics that are currently ineffective due to efflux mechanisms. Through a combination of rigorous experimental screening and in silico virtual screening we recently identified novel classes of EPIs that interact with the membrane fusion protein AcrA, a critical component of the AcrAB-TolC efflux pump in E...
June 26, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28648860/global-emergence-of-the-widespread-pseudomonas-aeruginosa-st235-clone
#15
Panisa Treepong, Veronica N Kos, Christophe Guyeux, Dominique S Blanc, Xavier Bertrand, Benoit Valot, Didier Hocquet
OBJECTIVES: Despite the non-clonal epidemic population structure of Pseudomonas aeruginosa, several multi-locus sequence types are distributed worldwide and are frequently associated with epidemics where multidrug resistance confounds treatment. ST235 is the most prevalent of these widespread clones. In this study we aimed to understand the origin of ST235 and the molecular basis for its success. METHODS: The genomes of 79 P. aeruginosa ST235 isolates collected worldwide over a 27-year period were examined...
June 22, 2017: Clinical Microbiology and Infection
https://www.readbyqxmd.com/read/28646205/comparative-nanouplc-ms-e-analysis-between-magainin-i-susceptible-and-resistant-escherichia-coli-strains
#16
Marlon H Cardoso, Keyla C de Almeida, Elizabete de S Cândido, André M Murad, Simoni C Dias, Octávio L Franco
In recent years the antimicrobial peptides (AMPs) have been prospected and designed as new alternatives to conventional antibiotics. Indeed, AMPs have presented great potential toward pathogenic bacterial strains by means of complex mechanisms of action. However, reports have increasingly emerged regarding the mechanisms by which bacteria resist AMP administration. In this context, we performed a comparative proteomic study by using the total bacterial lysate of magainin I-susceptible and -resistant E. coli strains...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28642736/identification-of-an-efflux-transporter-lmrb-regulating-stress-response-and-extracellular-polysaccharide-synthesis-in-streptococcus-mutans
#17
Jia Liu, Lihong Guo, Jianwei Liu, Jianying Zhang, Huihui Zeng, Yang Ning, Xi Wei
Efflux transporters have been implicated in regulating bacterial virulence properties such as resistance to antibiotics, biofilm formation and colonization. The pathogenicity of Streptococcus mutans, the primary etiologic agent of human dental caries, relies on the bacterium's ability to form biofilms on tooth surface. However, the studies on efflux transporters in S. mutans are scare and the function of these transporters remained to be clarified. In this study, we identified an efflux transporter (LmrB) in S...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28638412/molecular-identification-of-aminoglycoside-modifying-enzymes-and-plasmid-mediated-quinolone-resistance-genes-among-klebsiella-pneumoniae-clinical-isolates-recovered-from-egyptian-patients
#18
Mohamed F El-Badawy, Wael M Tawakol, Shaymaa W El-Far, Ibrahim A Maghrabi, Saleh A Al-Ghamdi, Moselhy S Mansy, Mohammed S Ashour, Mohamed M Shohayeb
Inappropriate use of antibiotics in clinical settings is thought to have led to the global emergence and spread of multidrug-resistant pathogens. The goal of this study was to investigate the prevalence of genes encoding aminoglycoside resistance and plasmid-mediated quinolone resistance among clinical isolates of Klebsiella pneumoniae. All K. pneumoniae isolates were phenotypically identified using API 20E and then confirmed genotypically through amplification of the specific K. pneumoniae phoE gene. All isolates were genotyped by the enterobacterial repetitive intergenic consensus polymerase chain reaction technique (ERIC-PCR)...
2017: International Journal of Microbiology
https://www.readbyqxmd.com/read/28625995/novel-antibiotic-resistance-determinants-from-agricultural-soil-exposed-to-antibiotics-widely-used-in-human-medicine-and-animal-farming
#19
Calvin Ho-Fung Lau, Kalene van Engelen, Stephen Gordon, Justin Renaud, Edward Topp
Antibiotic resistance has emerged globally as one of the biggest threats to human and animal health. Although the excessive use of antibiotics is recognized for accelerating the selection for resistance, there is a growing body of evidence suggesting that natural environments are "hotspots" for the development of both ancient and contemporary resistance mechanisms. Given that pharmaceuticals can be entrained onto agricultural land through anthropogenic activities, this could be a potential driver for the emergence and dissemination of resistance in soil bacteria...
June 16, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28621579/optimization-of-antimicrobial-photodynamic-therapy-in-biofilms-by-inhibiting-efflux-pump
#20
Tatiana Maria Starck Fogaça de Aguiar Coletti, Laura Marise de Freitas, Ana Marisa Fusco Almeida, Carla Raquel Fontana
BACKGROUND: One of the main mechanisms of microbial resistance is given by efflux pumps, which reduce the effectiveness of antimicrobials by decreasing their intracellular concentration. OBJECTIVE AND METHODS: Considering that efflux pump inhibitors are promising adjuvant molecules for antibiotics in infections, in this study, using XTT test and colony forming unit (CFU) counting, we evaluated the association between the pump inhibitor verapamil (VP) and the antimicrobial photodynamic therapy (aPDT) mediated by methylene blue (MB) in biofilms of Escherichia coli and Staphylococcus aureus to optimize the bacterial reduction...
July 2017: Photomedicine and Laser Surgery
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