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Small colony variant

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https://www.readbyqxmd.com/read/28915357/a-i-yigp-i-mutant-strain-is-a-small-colony-variant-of-i-e-coli-i-and-shows-pleiotropic-antibiotic-resistance
#1
Hui Xia, Qiongwei Tang, Jie Song, Jiang Ye, Haizhen Wu, Huizhan Zhang
Small colony variants (SCVs) are a commonly observed subpopulation of bacteria that have a small colony size and distinctive biochemical characteristics. SCVs are more resistant to some antibiotics than the wild-type, and usually cause persistent infections in the clinic. SCV studies have been very active during the past two decades, especially of <i>Staphylococcus aureus</i>. However, fewer studies on <i>Escherichia coli </i>SCVs exist, so we studied an <i>E. coli </i>SCV during an experiment involving the deletion of the<i> yigP</i> locus...
September 15, 2017: Canadian Journal of Microbiology
https://www.readbyqxmd.com/read/28874369/transcriptional-and-mutational-profiling-of-an-aminoglycoside-resistant-pseudomonas-aeruginosa-small-colony-variant
#2
Monika Schniederjans, Michal Koska, Susanne Häussler
Pseudomonas aeruginosa is a major causative agent of both acute and chronic infections. Although aminoglycoside antibiotics are very potent drugs to fight such infections, antibiotic failure is steadily increasing mainly due to increasing resistance of the bacteria. Many molecular mechanisms that determine resistance such as acquisition of genes encoding for aminoglycoside-inactivating enzymes or overexpression of efflux pumps have been elucidated. However, there are additional, less-well described mechanisms of aminoglycoside resistance...
September 5, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28859444/evaluation-of-combinations-of-putative-anti-biofilm-agents-and-antibiotics-to-eradicate-biofilms-of-staphylococcus-aureus-and-pseudomonas-aeruginosa
#3
Katherine Belfield, Roger Bayston, Nadzieja Hajduk, Georgia Levell, John P Birchall, Matija Daniel
Objectives: To evaluate potential anti-biofilm agents for their ability to enhance the activity of antibiotics for local treatment of localized biofilm infections. Methods: Staphylococcus aureus and Pseudomonas aeruginosa in vitro biofilm models were developed. The putative antibiotic enhancers N-acetylcysteine, acetylsalicylic acid, sodium salicylate, recombinant human deoxyribonuclease I, dispersin B, hydrogen peroxide and Johnson's Baby Shampoo (JBS) were tested for their anti-biofilm activity alone and their ability to enhance the activity of antibiotics for 7 or 14 days, against 5 day old biofilms...
September 1, 2017: Journal of Antimicrobial Chemotherapy
https://www.readbyqxmd.com/read/28845425/having-your-cake-and-eating-it-staphylococcus-aureus-small-colony-variants-can-evolve-faster-growth-rate-without-losing-their-antibiotic-resistance
#4
COMMENT
Gerrit Brandis, Sha Cao, Douglas L Huseby, Diarmaid Hughes
Staphylococcus aureus can produce small colony variants (SCVs) during infections. These cause significant clinical problems because they are difficult to detect in standard microbiological screening and are associated with persistent infections. The major causes of the SCV phenotype are mutations that inhibit respiration by inactivation of genes of the menadione or hemin biosynthesis pathways. This reduces the production of ATP required to support fast growth. Importantly, it also decreases cross-membrane potential in SCVs, resulting in decreased uptake of cationic compounds, with reduced susceptibility to aminoglycoside antibiotics as a consequence...
August 1, 2017: Microbial Cell
https://www.readbyqxmd.com/read/28843820/multiple-paths-towards-reduced-membrane-potential-and-concomitant-reduction-in-aminoglycoside-susceptibility-in-staphylococcus-aureus
#5
Martin Vestergaard, Katrine Nøhr-Meldgaard, Hanne Ingmer
Staphylococcus aureus confers life-threatening and difficult to treat infections worldwide and antimicrobial resistance is an increasing concern. While acquired resistance has been widely studied, little is known of the contributions from chromosomal determinants that upon inactivation may reduce the susceptibility towards antibiotics. The aim of this study was to identify genetic determinants that upon inactivation reduce aminoglycoside susceptibility in Staphylococcus aureus. We screened the Nebraska Transposon Mutant Library of 1920 single-gene inactivations in S...
August 23, 2017: International Journal of Antimicrobial Agents
https://www.readbyqxmd.com/read/28820897/persistent-infection-due-to-a-small-colony-variant-of-burkholderia-pseudomallei-leads-to-pd-1-upregulation-on-circulating-immune-cells-and-mononuclear-infiltration-in-viscera-of-experimental-balb-c-mice
#6
Jia-Xiang See, Samudi Chandramathi, Mahmood Ameen Abdulla, Jamuna Vadivelu, Esaki M Shankar
BACKGROUND: Melioidosis is a neglected tropical disease endemic across South East Asia and Northern Australia. The etiological agent, Burkholderia pseudomallei (B.pseudomallei), is a Gram-negative, rod-shaped, motile bacterium residing in the soil and muddy water across endemic regions of the tropical world. The bacterium is known to cause persistent infections by remaining latent within host cells for prolonged duration. Reactivation of the recrudescent disease often occurs in elders whose immunity wanes...
August 2017: PLoS Neglected Tropical Diseases
https://www.readbyqxmd.com/read/28769913/intracellular-survival-of-staphylococcus-aureus-in-endothelial-cells-a-matter-of-growth-or-persistence
#7
Guillaume Rollin, Xin Tan, Fabiola Tros, Marion Dupuis, Xavier Nassif, Alain Charbit, Mathieu Coureuil
The Gram-positive human pathogen Staphylococcus aureus is a leading cause of severe bacterial infections. Recent studies have shown that various cell types could readily internalize S. aureus and infected cells have been proposed to serve as vehicle for the systemic dissemination of the pathogen. Here we focused on the intracellular behavior of the Community-Associated Methicillin-Resistant S. aureus strain USA300. Supporting earlier observations, we found that wild-type S. aureus strain USA300 persisted for longer period within endothelial cells than within macrophages and that a mutant displaying the small colony variant phenotype (ΔhemDBL) had increased intracellular persistence...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28750619/the-practical-use-of-genome-sequencing-data-in-the-management-of-a-feline-colony-pedigree
#8
Fabiana H G Farias, Chad Tomlinson, Jeffrey Labuda, Gerardo Perez-Camargo, Rondo Middleton, Wesley C Warren
BACKGROUND: A higher prevalence of inherited disorders among companion animals are often rooted in their historical restricted artificial selection for a variety of observed phenotypes that eventually decreased genetic diversity. Cats have been afflicted with many inherited diseases due to domestication and intense breed selection. Advances in sequencing technology have generated a more comprehensive way to access genetic information from an individual, allowing identification of putative disease-causing variants and in practice a means to avoid their spread and thus better pedigree management...
July 27, 2017: BMC Veterinary Research
https://www.readbyqxmd.com/read/28720732/pseudomonas-aeruginosa-alters-staphylococcus-aureus-sensitivity-to-vancomycin-in-a-biofilm-model-of-cystic-fibrosis-infection
#9
Giulia Orazi, George A O'Toole
The airways of cystic fibrosis (CF) patients have thick mucus, which fosters chronic, polymicrobial infections. Pseudomonas aeruginosa and Staphylococcus aureus are two of the most prevalent respiratory pathogens in CF patients. In this study, we tested whether P. aeruginosa influences the susceptibility of S. aureus to frontline antibiotics used to treat CF lung infections. Using our in vitro coculture model, we observed that addition of P. aeruginosa supernatants to S. aureus biofilms grown either on epithelial cells or on plastic significantly decreased the susceptibility of S...
July 18, 2017: MBio
https://www.readbyqxmd.com/read/28717043/tandem-amplification-of-the-staphylococcal-cassette-chromosome-mec-element-can-drive-high-level-methicillin-resistance-in-methicillin-resistant-staphylococcus-aureus
#10
Laura A Gallagher, Simone Coughlan, Nikki S Black, Pierce Lalor, Elaine M Waters, Bryan Wee, Mick Watson, Tim Downing, J Ross Fitzgerald, Gerard T A Fleming, James P O'Gara
Hospital-associated methicillin-resistant Staphylococcus aureus (MRSA) strains typically express high-level, homogeneous (HoR) β-lactam resistance, whereas community-associated MRSA (CA-MRSA) more commonly express low-level heterogeneous (HeR) resistance. Expression of the HoR phenotype typically requires both increased expression of the mecA gene, carried on the staphylococcal cassette chromosome mec element (SCCmec), and additional mutational event(s) elsewhere on the chromosome. Here the oxacillin concentration in a chemostat culture of the CA-MRSA strain USA300 was increased from 8 μg/ml to 130 μg/ml over 13 days to isolate highly oxacillin-resistant derivatives...
September 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28714889/staphylococcus-aureus-regulator-sigma-b-is-important-to-develop-chronic-infections-in-hematogenous-murine-osteomyelitis-model
#11
Lorena Tuchscherr, Jennifer Geraci, Bettina Löffler
Staphylococcus aureus is a major pathogen causing bone infections that can become chronic and difficult to treat. Recently, we described the mechanism employed by S. aureus to switch to small colony variants (SCVs) and trigger intracellular bacterial persistence through the global stress regulator SigB. Here, we studied the role of SigB in the formation of chronic osteomyelitis. We used a murine hematogenous osteomyelitis model, where the mice were infected via the tail vein and subsequently developed chronic osteomyelitis...
July 15, 2017: Pathogens
https://www.readbyqxmd.com/read/28699877/isolation-and-characterization-of-kingella-negevensis-sp-nov-a-novel-kingella-species-detected-in-a-healthy-paediatric-population
#12
Nawal El Houmami, Sofiane Bakour, Janek Bzdrenga, Jaishiram Rathored, Hervé Seligmann, Catherine Robert, Nicholas Armstrong, Jacques Schrenzel, Didier Raoult, Pablo Yagupsky, Pierre-Edouard Fournier
We herein report the isolation and characterization of 21 Gram-stain-negative strains cultivated from the oropharynx of healthy children in Israel and Switzerland. Initially described as small colony variants of Kingella kingae, phenotypic analysis, biochemical analysis, phylogenetic analysis based on sequencing of the partial 16S rRNA gene and five housekeeping genes (abcZ, adk, G6PD, groEL and recA), and whole genome sequencing and comparison between members of the genera Kingella and Neisseria provided evidence for assigning them to the genus Kingella...
July 2017: International Journal of Systematic and Evolutionary Microbiology
https://www.readbyqxmd.com/read/28690982/deferiprone-and-gallium-protoporphyrin-have-the-capacity-to-potentiate-the-activity-of-antibiotics-in-staphylococcus-aureus-small-colony-variants
#13
Katharina Richter, Nicky Thomas, Guimin Zhang, Clive A Prestidge, Tom Coenye, Peter-John Wormald, Sarah Vreugde
Small colony variants (SCVs) of bacteria like Staphylococcus aureus are characterized by a reduced colony size and are linked to increased antibiotic tolerance and resistance. Their altered expression of virulence factors, slow growing properties and their ability to form biofilms make the eradication of SCVs challenging. In the context of biofilm-related infectious diseases involving S. aureus SCVs, a therapy targeting bacterial iron metabolism was evaluated. The combination of the iron-chelator deferiprone (Def) and the heme-analog gallium-protoporphyrin (GaPP), in solution and incorporated in a surgical wound gel, was tested for activity against planktonic and sessile SCVs...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28673558/characterization-of-first-hemin-requiring-pseudomonas-aeruginosa-small-colony-variants-from-the-blood-of-an-octogenarian-male-patient-with-double-pneumonitis
#14
Natsumi Nagano, Hideo Nakaya, Megumi Nagata, Toru Nishizawa, Ryuji Kawahara, Takehisa Matsumoto, Kozue Oana, Yoshiyuki Kawakami
A hemin-requiring Pseudomonas aeruginosa small-colony variant (SCV) was isolated from the blood of an octogenarian male-patient with double pneumonitis. The isolate was capable of growing on both sheep blood and chocolate agars but not on MacConkey agars without blood ingredient. Furthermore, the isolate revealed to grow only around the X-factor impregnated discs when examined using the X and V disc strips. However, not only RapID-NH system but also the VITEK2 system failed to identify the isolate. The isolate was finally identified as P...
June 30, 2017: Journal of Infection and Chemotherapy: Official Journal of the Japan Society of Chemotherapy
https://www.readbyqxmd.com/read/28666225/hplc-ms-ms-targeted-metabolic-profiling-reveals-distinct-metabolic-profiles-from-staphylococcus-aureus-small-colony-variants
#15
Chen Wang, Jiangjiang Zhu
Staphylococcus aureus is a world-wide health threat due to its prevalence and possible resistance to antibiotic treatment. A variety reasons can contribute to S. aureus antibiotic resistance and one group of phenotypes that may be discovered from S. aureus is named small-colony variants (SCVs). This study focused on applying a HPLC-MS/MS based targeted metabolic profiling approach to detect a set of metabolites that are dysregulated during S. aureus SCVs formation. Over one hundred and eighty metabolites were confidently detected and their difference between S...
August 15, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/28634236/alternative-evolutionary-pathways-for-drug-resistant-small-colony-variant-mutants-in-staphylococcus-aureus
#16
Sha Cao, Douglas L Huseby, Gerrit Brandis, Diarmaid Hughes
Staphylococcus aureus is known to generate small colony variants (SCVs) that are resistant to aminoglycoside antibiotics and can cause persistent and recurrent infections. The SCV phenotype is unstable, and compensatory mutations lead to restored growth, usually with loss of resistance. However, the evolution of improved growth, by mechanisms that avoid loss of antibiotic resistance, is very poorly understood. By selection with serial passaging, we isolated and characterized different classes of extragenic suppressor mutations that compensate for the slow growth of small colony variants...
June 20, 2017: MBio
https://www.readbyqxmd.com/read/28620368/an-arod-ochre-mutation-results-in-a-staphylococcus-aureus-small-colony-variant-that-can-undergo-phenotypic-switching-via-two-alternative-mechanisms
#17
Ping Zhang, John A Wright, Ahmed A Osman, Sean P Nair
Staphylococcus aureus can undergo phenotypic switching between a normal colony phenotype (NCP) and a small colony variant (SCV). The SCV phenotype confers increased antibiotic resistance and the capacity to persist within human tissues and cells, and because these cells can revert back to the NCP they cause chronic and/or recurrent infections that are very difficult to treat. A complete picture of the genetic events that can lead to phenotypic switching in S. aureus is currently lacking. We describe the selection of an SCV with a previously unreported genetic alteration leading to an ochre mutation of aroD...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28607159/mechanisms-of-pyocyanin-toxicity-and-genetic-determinants-of-resistance-in-staphylococcus-aureus
#18
Michael J Noto, William J Burns, William N Beavers, Eric P Skaar
Pseudomonas aeruginosa and Staphylococcus aureus are commonly isolated from polymicrobial infections, such as wound infections and chronic respiratory infections of persons with cystic fibrosis. Despite their co-isolation, P. aeruginosa produces substances toxic to S. aureus, including pyocyanin, a blue pigmented molecule that functions in P. aeruginosa virulence. Pyocyanin inhibits S. aureus respiration, forcing it to derive energy from fermentation and adopt a small colony variant (SCV) phenotype. The mechanisms by which S...
June 12, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28607014/np108-an-antimicrobial-polymer-with-activity-against-methicillin-and-mupirocin-resistant-staphylococcus-aureus
#19
Derry K Mercer, Laura K Katvars, Fiona Hewitt, Daniel W Smith, Jennifer Robertson, Deborah A O'Neil
Staphylococcus aureus is a clinically significant human pathogen that causes infectious diseases ranging from skin and soft tissue infections (SSTI) and health care-associated infections (HAI) to potentially fatal bacteremia and endocarditis. Nasal carriage of S. aureus, especially for persistent carriage, is associated with an increased risk of subsequent infection, particularly nosocomial and surgical site infections (SSI), usually via autoinfection. NP108 is a cationic antimicrobial polymer composed of generally recognized as safe (GRAS) amino acid building blocks...
September 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28584147/influence-of-is256-on-genome-variability-and-formation-of-small-colony-variants-in-staphylococcus-aureus
#20
Franziska Kleinert, René Kallies, Michael Hort, Annegret Zweynert, Christiane Szekat, Michael Nagel, Gabriele Bierbaum
Staphylococcus aureus has acquired resistance to nearly all antibiotics used in clinical practice. Whereas some resistance mechanisms are conferred by uptake of resistance genes, others evolve by mutation. In this study, IS256 has been shown to play a role, e.g., in S. aureus strains displaying intermediate resistance to vancomycin (VISA). To characterize the IS256 insertion sites in the genomes of two closely related sequence type 247 (ST247) VISA strains, all insertions were mapped in both VISA and a susceptible control strain...
August 2017: Antimicrobial Agents and Chemotherapy
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