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Small colony variant

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https://www.readbyqxmd.com/read/27920765/novel-pathways-for-ameliorating-the-fitness-cost-of-gentamicin-resistant-small-colony-variants
#1
Martin Vestergaard, Wilhelm Paulander, Bingfeng Leng, Jesper B Nielsen, Henrik T Westh, Hanne Ingmer
Small colony variants (SCVs) of the human pathogen Staphylococcus aureus are associated with persistent infections. Phenotypically, SCVs are characterized by slow growth and they can arise upon interruption of the electron transport chain that consequently reduce membrane potential and thereby limit uptake of aminoglycosides (e.g., gentamicin). In this study, we have examined the pathways by which the fitness cost of SCVs can be ameliorated. Five gentamicin resistant SCVs derived from S. aureus JE2 were independently selected on agar plates supplemented with gentamicin...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27903603/multicenter-evaluation-of-a-modified-cefoxitin-disk-diffusion-method-and-pbp2a-testing-to-predict-meca-mediated-oxacillin-resistance-in-atypical-staphylococcus-aureus
#2
Shelley A Miller, James Karichu, Peggy Kohner, Nicolynn Cole, Janet A Hindler, Robin Patel, Sandra Richter, Romney M Humphries
Phenotypic variants of Staphylococcus aureus display small colony size, reduced pigment, hemolysis and/or coagulase activity are periodically isolated by the clinical laboratory. Antimicrobial susceptibility testing (AST) of these isolates is complicated as many do not grow on routine AST media, including Mueller Hinton agar and cation-adjusted Mueller Hinton broth. This multi-center study evaluated cefoxitin disk diffusion for 37 isolates (156 readings) of atypical S. aureus with MHA supplemented with 5% sheep's blood (BMHA), using mecA PCR as the reference standard...
November 30, 2016: Journal of Clinical Microbiology
https://www.readbyqxmd.com/read/27881736/reactive-oxygen-species-drive-evolution-of-pro-biofilm-variants-in-pathogens-by-modulating-cyclic-di-gmp-levels
#3
Song Lin Chua, Yichen Ding, Yang Liu, Zhao Cai, Jianuan Zhou, Sanjay Swarup, Daniela I Drautz-Moses, Stephan Christoph Schuster, Staffan Kjelleberg, Michael Givskov, Liang Yang
The host immune system offers a hostile environment with antimicrobials and reactive oxygen species (ROS) that are detrimental to bacterial pathogens, forcing them to adapt and evolve for survival. However, the contribution of oxidative stress to pathogen evolution remains elusive. Using an experimental evolution strategy, we show that exposure of the opportunistic pathogen Pseudomonas aeruginosa to sub-lethal hydrogen peroxide (H2O2) levels over 120 generations led to the emergence of pro-biofilm rough small colony variants (RSCVs), which could be abrogated by l-glutathione antioxidants...
November 2016: Open Biology
https://www.readbyqxmd.com/read/27872182/an-ompr-envz-two-component-system-ortholog-regulates-phase-variation-osmotic-tolerance-motility-and-virulence-in-acinetobacter-baumannii-strain-ab5075
#4
Kyle A Tipton, Philip N Rather
: Recently, a novel phase-variable colony opacity phenotype was discovered in Acinetobacter baumannii strain AB5075, where colonies interconvert between opaque and translucent variants. Opaque colonies become mottled/sectored after 24 hours of growth due to translucent variants arising within the colony. This easily distinguishable opaque colony phenotype was used to screen for random transposon insertions that increased the frequency of sectoring at a time point when wild-type colonies were uniformly opaque...
November 21, 2016: Journal of Bacteriology
https://www.readbyqxmd.com/read/27861524/factors-associated-with-worse-lung-function-in-cystic-fibrosis-patients-with-persistent-staphylococcus-aureus
#5
Sibylle Junge, Dennis Görlich, Martijn den Reijer, Bärbel Wiedemann, Burkhard Tümmler, Helmut Ellemunter, Angelika Dübbers, Peter Küster, Manfred Ballmann, Cordula Koerner-Rettberg, Jörg Große-Onnebrink, Eberhardt Heuer, Wolfgang Sextro, Jochen G Mainz, Jutta Hammermann, Joachim Riethmüller, Ute Graepler-Mainka, Doris Staab, Bettina Wollschläger, Rüdiger Szczepanski, Antje Schuster, Friedrich-Karl Tegtmeyer, Sivagurunathan Sutharsan, Alexandra Wald, Jerzy-Roch Nofer, Willem van Wamel, Karsten Becker, Georg Peters, Barbara C Kahl
BACKGROUND: Staphylococcus aureus is an important pathogen in cystic fibrosis (CF). However, it is not clear which factors are associated with worse lung function in patients with persistent S. aureus airway cultures. Our main hypothesis was that patients with high S. aureus density in their respiratory specimens would more likely experience worsening of their lung disease than patients with low bacterial loads. METHODS: Therefore, we conducted an observational prospective longitudinal multi-center study and assessed the association between lung function and S...
2016: PloS One
https://www.readbyqxmd.com/read/27855187/characterization-of-a-vrag-mutant-in-a-genetically-stable-staphylococcus-aureus-small-colony-variant-and-preliminary-assessment-for-use-as-a-live-attenuated-vaccine-against-intrammamary-infections
#6
Julie Côté-Gravel, Eric Brouillette, Nataša Obradović, Céline Ster, Brian G Talbot, François Malouin
Staphylococcus aureus is a leading cause of bovine intramammary infections (IMIs) that can evolve into difficult-to-treat chronic mastitis. To date, no vaccine formulation has shown high protective efficacy against S. aureus IMI, partly because this bacterium can efficiently evade the immune system. For instance, S. aureus small colony variants (SCVs) have intracellular abilities and can persist without producing invasive infections. As a first step towards the development of a live vaccine, this study describes the elaboration of a novel attenuated mutant of S...
2016: PloS One
https://www.readbyqxmd.com/read/27835940/whole-genome-sequence-analysis-of-the-tallyho-jng-mouse
#7
James Denvir, Goran Boskovic, Jun Fan, Donald A Primerano, Jacaline K Parkman, Jung Han Kim
BACKGROUND: The TALLYHO/Jng (TH) mouse is a polygenic model for obesity and type 2 diabetes first described in the literature in 2001. The origin of the TH strain is an outbred colony of the Theiler Original strain and mice derived from this source were selectively bred for male hyperglycemia establishing an inbred strain at The Jackson Laboratory. TH mice manifest many of the disease phenotypes observed in human obesity and type 2 diabetes. RESULTS: We sequenced the whole genome of TH mice maintained at Marshall University to a depth of approximately 64...
November 11, 2016: BMC Genomics
https://www.readbyqxmd.com/read/27804985/a-murine-model-of-early-pseudomonas-aeruginosa-lung-disease-with-transition-to-chronic-infection
#8
H K Bayes, N Ritchie, S Irvine, T J Evans
Pseudomonas aeruginosa (PA) remains an important pathogen in patients with cystic fibrosis (CF) lung disease as well as non-CF bronchiectasis and chronic obstructive airways disease. Initial infections are cleared but chronic infection with mucoid strains ensues in the majority of CF patients and specific interventions to prevent this critical infection transition are lacking. The PA bead model has been widely used to study pulmonary P.aeruginosa infection but has limitations in animal husbandry and in accurately mimicking human disease...
November 2, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27632429/development-of-a-screening-system-for-inteins-active-in-protein-splicing-based-on-intein-insertion-into-the-lacz%C3%AE-peptide
#9
Maximilian Neugebauer, Jana K Böcker, Julian C J Matern, Shmuel Pietrokovski, Henning D Mootz
Protein splicing by inteins has found diverse applications in biotechnology, protein chemistry and chemical biology. Inteins display a wide range of efficiencies and rates unpredictable from their amino acid sequences. Here, we identified positions T22S and S35 in the LacZα peptide as intein insertion sites that strictly require protein splicing, in contrast to cleavage side-reactions, to allow for complementation of β-galactosidase activity. Both the cis-variant of the M86 mutant of the Ssp DnaB intein and a split form undergoing protein trans-splicing gave rise to formation of blue colonies in the β-galactosidase read-out...
January 1, 2017: Biological Chemistry
https://www.readbyqxmd.com/read/27606007/macrophage-adaptation-leads-to-parallel-evolution-of-genetically-diverse-escherichia-coli-small-colony-variants-with-increased-fitness-in-vivo-and-antibiotic-collateral-sensitivity
#10
Ricardo S Ramiro, Henrique Costa, Isabel Gordo
Small-colony variants (SCVs) are commonly observed in evolution experiments and clinical isolates, being associated with antibiotic resistance and persistent infections. We recently observed the repeated emergence of Escherichia coli SCVs during adaptation to the interaction with macrophages. To identify the genetic targets underlying the emergence of this clinically relevant morphotype, we performed whole-genome sequencing of independently evolved SCV clones. We uncovered novel mutational targets, not previously associated with SCVs (e...
September 2016: Evolutionary Applications
https://www.readbyqxmd.com/read/27600172/small-colony-variants-are-more-susceptible-to-copper-mediated-contact-killing-for-pseudomonas-aeruginosa-and-staphylococcus-aureus
#11
Sha Liu, Xue-Xian Zhang
Applying self-sanitising copper surfaces to commonly touched places within hospital facilities is an emerging strategy to prevent healthcare-associated infections (HAIs). This is owing to the fact that bacterial pathogens are rapidly killed on copper, a process termed contact killing. However, the mechanisms of contact killing are not fully understood, and the potential of bacterial pathogens to develop resistance has rarely been explored. Here, we hypothesize that bacteria are predominantly killed by a burst release of toxic copper ions, resulting from chemical reactions between bacterial cell surface components and metallic copper...
September 2, 2016: Journal of Medical Microbiology
https://www.readbyqxmd.com/read/27557703/detection-of-nucleotide-specific-crispr-cas9-modified-alleles-using-multiplex-ligation-detection
#12
R Kc, A Srivastava, J M Wilkowski, C E Richter, J A Shavit, D T Burke, S L Bielas
CRISPR/Cas9 genome-editing has emerged as a powerful tool to create mutant alleles in model organisms. However, the precision with which these mutations are created has introduced a new set of complications for genotyping and colony management. Traditional gene-targeting approaches in many experimental organisms incorporated exogenous DNA and/or allele specific sequence that allow for genotyping strategies based on binary readout of PCR product amplification and size selection. In contrast, alleles created by non-homologous end-joining (NHEJ) repair of double-stranded DNA breaks generated by Cas9 are much less amenable to such strategies...
2016: Scientific Reports
https://www.readbyqxmd.com/read/27472323/acute-generalized-exanthematous-pustulosis-pathogenesis-genetic-background-clinical-variants-and-therapy
#13
REVIEW
Laurence Feldmeyer, Kristine Heidemeyer, Nikhil Yawalkar
Acute generalized exanthematous pustulosis (AGEP) is a severe, usually drug-related reaction, characterized by an acute onset of mainly small non-follicular pustules on an erythematous base and spontaneous resolution usually within two weeks. Systemic involvement occurs in about 20% of cases. The course is mostly benign, and only in rare cases complications lead to life-threatening situations. Recent studies highlight the importance of genetic variations in interleukin-36 receptor antagonist gene (IL-36RN) in the pathogenesis of this disease...
2016: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/27458449/the-small-colony-variant-of-listeria-monocytogenes-is-more-tolerant-to-antibiotics-and-has-altered-survival-in-raw-264-7-murine-macrophages
#14
Thomas D Curtis, Lone Gram, Gitte M Knudsen
Small Colony Variant (SCV) cells of bacteria are a slow-growing phenotype that result from specific defects in the electron transport chain. They form pinpoint colonies on agar plates and have a variety of phenotypic characteristics, such as altered carbon metabolism, decreased toxin and lytic enzyme production, aminoglycoside resistance, and increased intracellular persistence. They are clinically relevant in Staphylococcus aureus and Pseudomonas aeruginosa, serving as a reservoir for recurrent or prolonged infections...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27405131/prevalence-antibiotic-and-pulsed-field-gel-electrophoresis-patterns-of-staphylococcus-aureus-small-colony-variants-in-cystic-fibrosis-patients
#15
Nagehan Pakasticali, Gamze Kaya, Unal Senel, Oner Kipritci, Zeynep Tamay, Nermin Guler, Hasan Nazik, Betigul Ongen
Staphylococcus aureus is the most common pathogen isolated from respiratory tract samples in cystic fibrosis (CF) cases. Rate of infection with S. aureus small-colony variants (SCVs) also is increasing in CF patients. In this study, we aimed to determine the prevalence, antibiotic susceptibility and genotypic property of S. aureus SCVs in respiratory tract samples of CF patients admitted to Istanbul Faculty of Medicine Hospital, Turkey. Among 305 respiratory tract samples from 84 CF patients, normal S. aureus isolates were present in 71% of the CF patients and S...
May 2016: Southeast Asian Journal of Tropical Medicine and Public Health
https://www.readbyqxmd.com/read/27310825/the-physiological-and-molecular-characterization-of-a-small-colony-variant-of-escherichia-coli-and-its-phenotypic-rescue
#16
Victor Santos, Irvin Hirshfield
Small colony variants (SCVs) can be defined as a naturally occurring sub-population of bacteria characterized by their reduced colony size and distinct biochemical properties. SCVs of Staphylococcus aureus have been studied extensively over the past two decades due to their role in recurrent human infections. However, little work has been done on SCVs of Escherichia coli, and this work has focused on the physiology and morphology that define these colonies of E. coli, such as small size and slow growth. E. coli strain JW0623, has a null lipA mutation in the lipoic acid synthase gene (lipA), and is a lipoic acid auxotroph...
2016: PloS One
https://www.readbyqxmd.com/read/27294200/a-methyl-4-oxo-4-phenylbut-2-enoate-with-in-vivo-activity-against-mrsa-that-inhibits-menb-in-the-bacterial-menaquinone-biosynthesis-pathway
#17
Joe S Matarlo, Yang Lu, Fereidoon Daryaee, Taraneh Daryaee, Bela Ruzsicska, Stephen G Walker, Peter J Tonge
4-Oxo-4-phenyl-but-2-enoates inhibit MenB, the 1,4-dihydroxyl-2-naphthoyl-CoA synthase in the bacterial menaquinone (MK) biosynthesis pathway, through the formation of an adduct with coenzyme A (CoA). Here, we show that the corresponding methyl butenoates have MIC values as low as 0.35-0.75 µg/mL against drug sensitive and resistant strains of Staphylococcus aureus. Mode of action studies on the most potent compound, methyl 4-(4-chlorophenyl)-4-oxobut-2-enoate (1), reveal that 1 is converted into the corresponding CoA adduct in S...
May 13, 2016: ACS Infectious Diseases
https://www.readbyqxmd.com/read/27245674/phenotypic-and-genetic-changes-in-the-life-cycle-of-small-colony-variants-of-salmonella-enterica-serotype-typhimurium-induced-by-streptomycin
#18
Wanli Li, Yinghui Li, Yarong Wu, Yujun Cui, Yao Liu, Xiaolu Shi, Qian Zhang, Qiongcheng Chen, Qun Sun, Qinghua Hu
BACKGROUND: Small colony variants (SCVs), constituting a slow-growing subpopulation of bacteria that facilitates persistence in lethal environmental conditions, are able to revert to the phenotype of rapid growth for further proliferation and transmission. Salmonella enterica serotype Typhimurium is one of the most important foodborne pathogens. This study investigated the genetic mechanisms how SCVs induced by streptomycin reverted to the fast-growing phenotype and the phenotypic changes of SCVs among their complete life cycle in S...
May 31, 2016: Annals of Clinical Microbiology and Antimicrobials
https://www.readbyqxmd.com/read/27190203/parallel-evolution-in-streptococcus-pneumoniae-biofilms
#19
Nicholas W V Churton, Raju V Misra, Robert P Howlin, Raymond N Allan, Johanna Jefferies, Saul N Faust, Saheer E Gharbia, Richard J Edwards, Stuart C Clarke, Jeremy S Webb
Streptococcus pneumoniae is a commensal human pathogen and the causative agent of various invasive and noninvasive diseases. Carriage of the pneumococcus in the nasopharynx is thought to be mediated by biofilm formation, an environment where isogenic populations frequently give rise to morphological colony variants, including small colony variant (SCV) phenotypes. We employed metabolic characterization and whole-genome sequencing of biofilm-derived S. pneumoniae serotype 22F pneumococcal SCVs to investigate diversification during biofilm formation...
2016: Genome Biology and Evolution
https://www.readbyqxmd.com/read/27169240/-effect-of-stress-on-emergence-of-antibiotic-resistant-escherichia-coli-cells
#20
N G Loiko, A N Kozlova, Yu A Nikolaev, A M Gaponov, A V Tutel'yan, G I El'-Registan
Effect of sublethal doses of physical and chemical stressors (heat shock for 2 h at 45 degrees C and addition of C12-alkylhydroxybenzene, a microbial alarmone) on development of resistance to the subsequent lethal antibiotic attack and the role of the time interval between these treatments were studied on a submerged batch culture of Escherichia coli 12. The interval sufficient for the development of stress response provides for development of temporary adaptive resistance to the antibiotic attack, resulting in increased number of surviving persister cells...
September 2015: Mikrobiologiia
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