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Small colony variant

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https://www.readbyqxmd.com/read/28720732/pseudomonas-aeruginosa-alters-staphylococcus-aureus-sensitivity-to-vancomycin-in-a-biofilm-model-of-cystic-fibrosis-infection
#1
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-sccmec-can-drive-high-level-methicillin-resistance-in-mrsa
#2
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 strains typically express high level, homogenous (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 Staphylococcus cassette chromosome SCCmec element, 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...
July 17, 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
#3
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
#4
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 12, 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
#5
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
#6
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
#7
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...
June 20, 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
#8
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
#9
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
#10
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
#11
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), healthcare associated infections (HAI) to potentially fatal bacteraemia and endocarditis. Nasal carriage of S. aureus, especially 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...
June 12, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28584147/influence-of-is256-on-genome-variability-and-formation-of-scv-in-staphylococcus-aureus
#12
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. Here, the insertion sequence 256 (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 (ST) 247 VISA strains, all insertions were mapped in both VISA and a susceptible control strain...
June 5, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28523838/an-unsaturated-quinolone-n-oxide-of-pseudomonas-aeruginosa-modulates-growth-and-virulence-of-staphylococcus-aureus
#13
Dávid Szamosvári, Thomas Böttcher
The pathogen Pseudomonas aeruginosa produces over 50 different quinolones, 16 of which belong to the class of 2-alkyl-4-quinolone N-oxides (AQNOs) with various chain lengths and degrees of saturation. We present the first synthesis of a previously proposed unsaturated compound that is confirmed to be present in culture extracts of P. aeruginosa, and its structure is shown to be trans-Δ(1) -2-(non-1-enyl)-4-quinolone N-oxide. This compound is the most active agent against S.  aureus, including MRSA strains, by more than one order of magnitude whereas its cis isomer is inactive...
June 12, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28521511/effects-of-adaptation-to-carvacrol-on-staphylococcus-aureus-in-the-planktonic-and-biofilm-phases
#14
Antonia Nostro, Andreana Marino, Giovanna Ginestra, Luigina Cellini, Mara Di Giulio, Giuseppe Bisignano
The effect of exposure to sub-minimum inhibitory concentrations of carvacrol, for either 3-10 days, on direct (carvacrol) or cross-protection (cinnamaldehyde, eugenol, antibiotics) and the influence on planktonic and biofilm growth of four Staphylococcus aureus strains were reported. The sequential exposure to carvacrol resulted in a direct protection that was more evident in two of the four strains after 10 days. No significant cross-protection against cinnamaldehyde, eugenol and antibiotics was detected...
May 18, 2017: Biofouling
https://www.readbyqxmd.com/read/28515299/a-diverse-range-of-novel-rna-viruses-in-geographically-distinct-honey-bee-populations
#15
Emily J Remnant, Mang Shi, Gabriele Buchmann, Tjeerd Blacquière, Edward C Holmes, Madeleine Beekman, Alyson Ashe
Understanding the diversity and consequences of viruses present in honey bees is critical to maintain pollinator health and manage the spread of disease. The viral landscape of honey bees (Apis mellifera) has changed dramatically since the emergence of the parasitic mite Varroa destructor, which increased the spread of virulent variants of viruses such as Deformed wing virus. Previous genomic studies have focused on colonies suffering from Varroa and virulent viruses, which could mask other viral species present in honey bees, resulting in a distorted view of viral diversity...
May 17, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28461319/bacteriophage-lysin-cf-301-a-potent-antistaphylococcal-biofilm-agent
#16
Raymond Schuch, Babar K Khan, Assaf Raz, Jimmy A Rotolo, Michael Wittekind
Biofilms pose a unique therapeutic challenge because of the antibiotic tolerance of constituent bacteria. Treatments for biofilm-based infections represent a major unmet medical need, requiring novel agents to eradicate mature biofilms. Our objective was to evaluate bacteriophage lysin CF-301 as a new agent to target Staphylococcus aureus biofilms. We used minimum biofilm-eradicating concentration (MBEC) assays on 95 S. aureus strains to obtain a 90% MBEC (MBEC90) value of ≤0.25 μg/ml for CF-301. Mature biofilms of coagulase-negative staphylococci, Streptococcus pyogenes, and Streptococcus agalactiae were also sensitive to disruption, with MBEC90 values ranging from 0...
July 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28421166/in-vivo-and-in-vitro-interactions-between-pseudomonas-aeruginosa-and-staphylococcus-spp
#17
REVIEW
An Hotterbeekx, Samir Kumar-Singh, Herman Goossens, Surbhi Malhotra-Kumar
The significance of polymicrobial infections is increasingly being recognized especially in a biofilm context wherein multiple bacterial species-including both potential pathogens and members of the commensal flora-communicate, cooperate, and compete with each other. Two important bacterial pathogens that have developed a complex network of evasion, counter-inhibition, and subjugation in their battle for space and nutrients are Pseudomonas aeruginosa and Staphylococcus aureus. Their strain- and environment-specific interactions, for instance in the cystic fibrosis lung or in wound infections, show severe competition that is generally linked to worse patient outcomes...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28393875/oldest-varroa-tolerant-honey-bee-population-provides-insight-into-the-origins-of-the-global-decline-of-honey-bees
#18
L E Brettell, S J Martin
The ecto-parasitic mite Varroa destructor has transformed the previously inconsequential Deformed Wing Virus (DWV) into the most important honey bee viral pathogen responsible for the death of millions of colonies worldwide. Naturally, DWV persists as a low level covert infection transmitted between nest-mates. It has long been speculated that Varroa via immunosuppression of the bees, activate a covert infection into an overt one. Here we show that despite Varroa feeding on a population of 20-40 colonies for over 30 years on the remote island of Fernando de Noronha, Brazil no such activation has occurred and DWV loads have remained at borderline levels of detection...
April 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28328157/lack-of-small-colony-variants-of-staphylococcus-aureus-from-lower-respiratory-tract-specimens
#19
Rosemary Carzino, Emily Hart, Philip Sutton, Louise King, Sarath Ranganathan
BACKGROUND: Small-colony variants (SCVs) of Staphylococcus aureus are associated with worse lung disease in children with Cystic Fibrosis (CF), exhibit a higher resistance to antibiotics and co-colonize more commonly with Pseudomonas aeruginosa compared to the normal phenotype. The prevalence of SCVs in lower airway specimens from children with CF is largely unknown. METHODS: Each visible morphotype of S. aureus was subcultured onto horse blood agar (HBA) to enable identification of SCVs...
May 2017: Pediatric Pulmonology
https://www.readbyqxmd.com/read/28302951/generation-of-small-colony-variants-in-biofilms-by-escherichia-coli-harboring-a-conjugative-f-plasmid
#20
Yosuke Tashiro, Hiroaki Eida, Satoshi Ishii, Hiroyuki Futamata, Satoshi Okabe
A conjugative F plasmid induces mature biofilm formation by Escherichia coli by promoting F-pili-mediated cell-cell interactions and increasing the expression of biofilm-related genes. We herein demonstrated another function for the F plasmid in E. coli biofilms; it contributes to the emergence of genetic and phenotypic variations by spontaneous mutations. Small colony variants (SCVs) were more frequently generated in a continuous flow-cell biofilm than in the planktonic state of E. coli harboring the F plasmid...
March 31, 2017: Microbes and Environments
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