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Small colony variant

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https://www.readbyqxmd.com/read/28634236/alternative-evolutionary-pathways-for-drug-resistant-small-colony-variant-mutants-in-staphylococcus-aureus
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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-anti-staphylococcal-biofilm-agent
#9
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 ninety-five S. aureus strains to obtain a 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...
May 1, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28421166/in-vivo-and-in-vitro-interactions-between-pseudomonas-aeruginosa-and-staphylococcus-spp
#10
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
#11
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
#12
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
#13
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
https://www.readbyqxmd.com/read/28272333/a-comparison-of-deformed-wing-virus-in-deformed-and-asymptomatic-honey-bees
#14
Laura E Brettell, Gideon J Mordecai, Declan C Schroeder, Ian M Jones, Jessica R da Silva, Marina Vicente-Rubiano, Stephen J Martin
Deformed wing virus (DWV) in association with Varroa destructor is currently attributed to being responsible for colony collapse in the western honey bee (Apis mellifera). The appearance of deformed individuals within an infested colony has long been associated with colony losses. However, it is unknown why only a fraction of DWV positive bees develop deformed wings. This study concerns two small studies comparing deformed and non-deformed bees. In Brazil, asymptomatic bees (no wing deformity) that had been parasitised by Varroa as pupae had higher DWV loads than non-parasitised bees...
March 7, 2017: Insects
https://www.readbyqxmd.com/read/28258231/antibiotic-tolerance-and-the-alternative-lifestyles-of-staphylococcus-aureus
#15
REVIEW
Long M G Bui, Brian P Conlon, Stephen P Kidd
Staphylococcus aureus has an incredible ability to survive, either by adapting to environmental conditions or defending against exogenous stress. Although there are certainly important genetic traits, in part this ability is provided by the breadth of modes of growth S. aureus can adopt. It has been proposed that while within their host, S. aureus survives host-generated and therapeutic antimicrobial stress via alternative lifestyles: a persister sub-population, through biofilm growth on host tissue or by growing as small colony variants (SCVs)...
February 28, 2017: Essays in Biochemistry
https://www.readbyqxmd.com/read/28246015/exome-array-analysis-identifies-variants-in-spocd1-and-btn3a2-that-affect-risk-for-gastric-cancer
#16
Meng Zhu, Caiwang Yan, Chuanli Ren, Xiaodan Huang, Xun Zhu, Haiyong Gu, Meilin Wang, Shouyu Wang, Yong Gao, Yong Ji, Xiaoping Miao, Ming Yang, Jinfei Chen, Jiangbo Du, Tongtong Huang, Yue Jiang, Juncheng Dai, Hongxia Ma, Jianwei Zhou, Zhaoming Wang, Zhibin Hu, Guozhong Ji, Zhengdong Zhang, Hongbing Shen, Yongyong Shi, Guangfu Jin
BACKGROUND & AIMS: Several genetic variants have been associated with gastric cancer risk, although these account for only a fraction of cases of gastric cancer. We aimed to identify low-frequency and other genetic variants that determine gastric cancer susceptibility. METHODS: We performed exome array analysis of DNA in blood samples from 1113 patients with gastric cancer, collected at hospitals from 2006 to 2010 in China, and 1848 individuals without cancer (controls) undergoing physical examinations...
February 27, 2017: Gastroenterology
https://www.readbyqxmd.com/read/28209530/solute-carrier-family-39-member-6-gene-promotes-aggressiveness-of-esophageal-carcinoma-cells-by-increasing-intracellular-levels-of-zinc-activating-phosphatidylinositol-3-kinase-signaling-and-up-regulating-genes-that-regulate%C3%A2-metastasis
#17
Xinxin Cheng, Lixuan Wei, Xudong Huang, Jian Zheng, Mingming Shao, Ting Feng, Jun Li, Yaling Han, Wenle Tan, Wen Tan, Dongxin Lin, Chen Wu
BACKGROUND & AIMS: A common variant in the solute carrier family 39 member 6 gene (SLC39A6) has been associated with survival times of patients with esophageal squamous cell carcinoma (ESCC). We investigated the function of SLC39A6 and ways in which this variant affects tumor progression by studying ESCC samples and cell lines. METHODS: SLC39A6 was expressed or knocked down by expression of short hairpin RNAs in ESCC cells (KYSE30 and KYSE450) and HeLa cells using lentiviral vectors; we analyzed effects on proliferation, colony formation, migration, and invasion in vitro...
February 14, 2017: Gastroenterology
https://www.readbyqxmd.com/read/28193172/comparison-of-pathogenic-and-non-pathogenic-enterococcus-cecorum-strains-from-different-animal-species
#18
Arne Jung, Martin Metzner, Martin Ryll
BACKGROUND: Enterococcus cecorum (EC) infection currently is one of the most important bacterial diseases of modern broiler chickens but can also affect ducks or other avian species. However, little is known concerning pathogenesis of EC and most studies concentrate on examinations of EC strains from broilers only. The objective of this study was to compare pathogenic and commensal EC strains from different animal species concerning different phenotypic and genotypic traits. RESULTS: Pathogenic and commensal EC strains were not clearly separated from each other in a phylogenetic tree based on partial sequences of the 16S-rRNA-gene and also based on the fatty acid profile determined with gas chromatography...
February 13, 2017: BMC Microbiology
https://www.readbyqxmd.com/read/28167688/implant-associated-esbl-klebsiella-pneumonia-producing-small-colony-variant-bone-and-joint-infection-in-a-healthy-40-year-old-man
#19
Cécile Ronde-Oustau, Sébastien Lustig, Céline Dupieux, Tristan Ferry
No abstract text is available yet for this article.
February 6, 2017: BMJ Case Reports
https://www.readbyqxmd.com/read/28071679/novel-long-chain-compounds-with-both-immunomodulatory-and-mena-inhibitory-activities-against-staphylococcus-aureus-and-its-biofilm
#20
Seoung-Ryoung Choi, Joel Frandsen, Prabagaran Narayanasamy
Menaquinone (MK) biosynthesis pathway is a potential target for evaluating antimicrobials in gram-positive bacteria. Here, 1,4-dihydroxy-2-naphthoate prenyltransferase (MenA) was targeted to reduce methicillin-resistant Staphylococcus aureus (MRSA) growth. MenA inhibiting, long chain-based compounds were designed, synthesized and evaluated against MRSA and menaquinone utilizing bacteria in aerobic conditions. The results showed that these bacteria were susceptible to most of the compounds. Menaquinone (MK-4) supplementation rescued MRSA growth, suggesting these compounds inhibit MK biosynthesis...
January 10, 2017: Scientific Reports
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