Search results for "(Staphylococcus)"
showing 10 items of 371 documents
Biomolecule-corona formation confers resistance of bacteria to nanoparticle-induced killing: Implications for the design of improved nanoantibiotics
2018
Abstract Multidrug-resistant bacterial infections are a global health threat. Nanoparticles are thus investigated as novel antibacterial agents for clinical practice, including wound dressings and implants. We report that nanoparticles' bactericidal activity strongly depends on their physical binding to pathogens, including multidrug-resistant primary clinical isolates, such as Staphylococcus aureus , Klebsiella pneumoniae or Enterococcus faecalis . Using controllable nanoparticle models, we found that nanoparticle-pathogen complex formation was enhanced by small nanoparticle size rather than material or charge, and was prevented by 'stealth' modifications. Nanoparticles seem to preferentia…
Synthesis and antimicrobial screening of tetra Schiff bases of 1,2,4,5-tetra (5-amino-1,3,4-thiadiazole-2-yl)benzene
2014
Abstract In the present study, novel tetra Schiff bases were synthesized by condensation of 1,2,4,5-tetra (5-amino-1,3,4-thiadiazole-2-yl)benzene with different aromatic aldehydes. The chemical structures were confirmed by means of IR, 1 H NMR, 13 C NMR, and elemental analysis. All compounds were screened for antibacterial ( Staphylococcus aureus ATCC-9144, Staphylococcus epidermidis ATCC-155, Micrococcus luteus ATCC-4698, Bacillus cereus ATCC-11778, Escherichia coli ATCC-25922, and Pseudomonas aeruginosa ATCC-2853) and antifungal ( Aspergillus niger ATCC-9029 and Aspergillus fumigatus ATCC-46645) activities by paper disc diffusion technique. The minimum inhibitory concentrations (MICs) of …
Sesterterpenes and macrolide derivatives from the endophytic fungus Aplosporella javeedii.
2020
Abstract Five sesterterpenes (1–5) including two new compounds (1 and 2), as well as a new (6) and a known macrolide (7) were isolated from the endophytic fungus Aplosporella javeedii. The structures of the new compounds were elucidated by analysis of their 1D and 2D NMR and HRMS data as well as by comparison with the literature. Compound 4 and its acetyl derivatives 4a, 4b, 4c which were prepared by acetylation of 4 exhibited moderate cytotoxicity against the mouse lymphoma cell line L5178Y with IC50 values ranging from 6.2 to 12.8 μM, respectively. Moreover, 4a and 4c exhibited also cytotoxicity against human leukemia (Jurkat J16) and lymphoma (Ramos) cell lines. Compound 7 showed strong …
Azacoccones F-H, new flavipin-derived alkaloids from an endophytic fungus Epicoccum nigrum MK214079.
2020
Abstract Three new flavipin-derived alkaloids, azacoccones F-H (1–3), along with six known compounds (4–9) were isolated from the endophytic fungus Epicoccum nigrum MK214079 associated with leaves of Salix sp. The structures of the new compounds were established by analysis of their 1D/2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectroscopy (HRESIMS) data. The absolute configuration of azacoccones F-H (1–3) was determined by comparison of experimental electronic circular dichroism (ECD) data with reported ones and biogenetic considerations. Epicocconigrone A (4), epipyrone A (5), and epicoccolide B (6) exhibited moderate antibacterial activity again…
Superior Antibacterial Activity of Integral Lemon Pectin Extracted via Hydrodynamic Cavitation
2020
Abstract Pectin extracted via hydrodynamic cavitation in water only from waste lemon peel and further isolated via freeze drying displays significant antibacterial activity against Staphylococcus aureus, a Gram positive pathogen which easily contaminates food. The antibacterial effect of the new IntegroPectin is largely superior to that of commercial citrus pectin, opening the way to advanced applications of a new bioproduct now obtainable in large amounts and at low cost from citrus juice industry's waste.
Seasonal variations of antimicrobial activity and chemical composition of essential oils extracted from three Citrus limon L. Burm. cultivars
2014
In order to investigate the seasonal variations of antimicrobial properties and chemical composition of essential oils (EOs), three different cultivars of Citrus limon L. Burm. spp. (Femminello Santa Teresa, Monachello and Femminello Continella) were collected at 6-week intervals, from December 2012 to April 2013, for a total of four harvests. The EOs were extracted from lemon peel by hydro-distillation. The antimicrobial activity, tested by paper disc diffusion method, was evaluated against common food-related pathogenic bacteria (Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica and Enterobacter spp.). EOs were more effective against Gram-positive than Gram-negative bacte…
Phenotypic and genotypic evaluation of slime production by conventional and molecular microbiological techniques.
2009
Twenty-nine staphylococcal isolates from different clinical samples were tested for slime production: phenotypic characterization was carried out using Christensen test (tube test) and Congo red agar plate test (CRA plate test), while the presence and expression of icaA and icaD genes were evaluated by real-time PCR. In 79.3% of studied strains there was a concordance between slime production and presence of icaA and icaD genes, and between lack of slime production and absence of both or only one of the tested genes. In four of five strains where positive phenotype was not associated with the presence of ica genes, gene co-expression (evaluated by mRNA determination) was lacking, while in o…
Der Einflu� von Antibiotica auf die �berlebensrate von Mikroorganismen bei tiefen Temperaturen
1959
Die Lebendkeimzahl in einer Suspension vonE. coli nimmt bei +4°C langsam zu, nimmt bei-5°C wenig ab und fallt bei-19°C innerhalb von 24 Std stark, wahrend die Verringerung in den folgenden Tagen nur noch gering ist. Streptomycin und Penicillin vermindern in allen 3 Temperaturbereichen die Keimkonzentration in Abhangigkeit von der Antibioticumkonzentration. Subbakteriostatische Konzentrationen von Streptomycin haben bei-19°C eine zusatzliche Wirkung. Die Resistenz der in uberbakteriostatischen Antibioticakonzentrationen bei diesen Temperaturen uberlebenden Keime ist gegenuber dem Ausgangsstamm weder erhoht noch vermindert.
Behavior of four main dairy pathogenic bacteria during manufacturing and ripening of pecorino siciliano cheese
2020
Background: Consumption of raw cheese may be associated with different diseases. This study aimed to evaluate behavior of four pathogenic bacteria during manufacture and ripening of Protected Designation of Origin (PDO) Pecorino Siciliano cheese.
 Methods: The experimental cheese groups were inoculated with pathogenic bacteria, including Escherichia coli O157, Listeria monocytogenes, Salmonella Enteritidis, and Staphylococcus aureus. The cheese making processes were monitored from milk curdling until 3 months ripened cheeses and the levels of Lactic Acid Bacteria (LAB) and the four dairy pathogens were evaluated by plate counts. Randomly Amplified Polymorphic DNA (RAPD)-Polymerase Chai…
Staphylococcal α-toxin: the role of the N-terminus in formation of the heptameric pore — a fluorescence study1This work contains parts of the M.D. th…
1997
Staphylococcus aureus alpha-toxin forms heptameric pores on eukaryotic cell membranes. Assembly of the heptamer precedes formation of the transmembrane pore. The latter event depends on a conformational change that drives a centrally located stretch of 15 amino acid residues into the lipid bilayer. A second region of the molecule that has been implicated in the pre-pore to pore transition is the far N-terminus. Here, we used fluorescently labeled single cysteine replacement mutants to analyze the functional role of the far N-terminus of alpha-toxin. Pyrene attached to mutants S3C, I5C and 17C forms excimers within the toxin pore complex. This indicates that the distance of adjacent N-termin…