Current Issue : October - December Volume : 2016 Issue Number : 4 Articles : 6 Articles
Background: Rapid identification and antimicrobial susceptibility testing (AST) of the causative agent(s) of\nbloodstream infections can lead to prompt appropriate antimicrobial therapy. To shorten species identification,\nin this study bacteria were recovered from monomicrobial blood cultures by serum separator tubes and spotted\nonto the target plate for direct MALDI-TOF MS identification. Proper antibiotics were selected for direct AST\nbased on species identification. In order to obtain rapid AST results, bacteria were recovered from positive blood\ncultures by two different protocols: by serum separator tubes (further referred to as PR1), or after a short-term\nsubculture in liquid medium (further referred to as PR2). The results were compared with those obtained by the\nmethod currently used in our laboratory consisting in identification by MALDI-TOF and AST by Vitek 2 or\nSensititre on isolated colonies.\nResults: The direct MALDI-TOF method concordantly identified with the current method 97.5 % of the Gram-negative\nbacteria and 96.1 % of the Gram-positive cocci contained in monomicrobial blood cultures. The direct AST by PR1 and\nPR2 for all isolate/antimicrobial agent combinations was concordant/correct with the current method for 87.8 and 90.\n5 % of Gram-negative bacteria and for 93.1 and 93.8 % of Gram-positive cocci, respectively. In particular, 100 %\ncategorical agreement was found with levofloxacin for Enterobacteriaceae by both PR1 and PR2, and 99.0 and 100 %\ncategorical agreement was observed with linezolid for Gram-positive cocci by PR1 and PR2, respectively. There was no\nsignificant difference in accuracy between PR1 and PR2 for Gram-negative bacteria and Gram-positive cocci.\nConclusions: This newly described method seems promising for providing accurate AST results. Most importantly,\nthese results would be available in a few hours from blood culture positivity, which would help clinicians to promptly\nconfirm or streamline an effective antibiotic therapy in patients with bloodstream infections....
Tailored nanoparticles offer a novel approach to fight\nantibiotic-resistant microorganisms. We analysed\nbiogenic selenium nanoparticles (SeNPs) of bacterial\norigin to determine their antimicrobial activity\nagainst selected pathogens in their planktonic and\nbiofilm states. SeNPs synthesized by Gram-negative\nStenotrophomonas maltophilia [Sm-SeNPs()] and\nGram-positive Bacillus mycoides [Bm-SeNPs(+)]\nwere active at low minimum inhibitory concentrations\nagainst a number of clinical isolates of Pseudomonas\naeruginosa but did not inhibit clinical\nisolates of the yeast species Candida albicans and\nC. parapsilosis. However, the SeNPs were able to\ninhibit biofilm formation and also to disaggregate the\nmature glycocalyx in both P. aeruginosa and Candida\nspp. The Sm-SeNPs() and Bm-SeNPs(+) both\nachieved much stronger antimicrobial effects than\nsynthetic selenium nanoparticles (Ch-SeNPs). Dendritic\ncells and fibroblasts exposed to Sm-SeNPs(),\nBm-SeNPs(+) and Ch-SeNPs did not show any loss\nof cell viability, any increase in the release of reactive\noxygen species or any significant increase in the secretion of pro-inflammatory and immunostimulatory\ncytokines. Biogenic SeNPs therefore appear to\nbe reliable candidates for safe medical applications,\nalone or in association with traditional antibiotics, to\ninhibit the growth of clinical isolates of P. aeruginosa\nor to facilitate the penetration of P. aeruginosa\nand Candida spp. biofilms by antimicrobial agents....
The aim of this research was to find a new microbial source for chitosanase production. Optimization of the fermentation conditions and medium compositions to maximize the enzyme production using one variable at a time technique, characterization of the crude enzyme as well as studying the ability of this enzyme to produce chitooligosaccharides from chitosan at different times that evaluated by thin-layer chromatography plate. Over 13 microorganisms screened for chitosanase production, an isolate identified as Dothideomycetes sp. css035 secreted a considerable value of inducible chitosanase (1.27 U/ml). The highest chitosanase production was induced by the medium composition g/L: soluble chitosan, 2; K2HPO4, 1.0; MgSO4, 0.3; KCl, 4.0; yeast extract, 15.0; FeSO4, 0.01; at pH 5, 30°C and 180 rpm for three days. The optimization study was markedly enhanced the production of the extracellular and the cell bound chitosanase from 1.27 U/ml and 11.9 U/dry weight to 10.2 U/ml and 298.56 U/dry weight. The crude extracellular chitosanase was optimally active at pH 4.5 and temperature 60°C with 1% soluble chitosan. The produced Dothideomycetes sp. css035 chitosanase exhibited a good stability over pH range from 4 to 5.5 and thermostable below 45°C in the absence of the chitosan. Thin-layer chromatography plate clearly visualized the efficiency of the produced chitosanase to hydrolyze chitosan to chitooligosaccharides. The highest concentration of chitooligosaccharides was produced after 4 h at pH 5 and 60°C with 0.15U/mg substrate....
Methicillin-sensitive and resistant Staphylococcus aureus (MSSA and MRSA, respectively) can cause\nnon-tuberculosis infectious spondylitis. In 43 cases of bacterial infectious spondylitis, Mycobacterium\ntuberculosis and S. aureus were the two major causative pathogens. MRSA caused more anterior\noperations and thoracic infections, while MSSA caused more posterior infections and lumbar\ninfections. Differences between six S. aureus isolates from infectious spondylitis were characterized.\nMLST and staphylococcal cassette chromosome mec (SCCmec) analysis identified MSSA\nST959 and ST30 isolates, MRSA ST239/SCCmec IIIA isolates 2 and 3, ST59/SCCmec IIIA-like isolate\n6, and ST30/SCCmec IV isolate 5. While all of the isolates were resistant to penicillin and ampicillin,\nthe MRSA isolates were more resistant than the MSSA isolates. Carbapenem-resistant MRSA\nST239/SCCmec IIIA and ST59/SCCmec IIIA-like isolates of the agr1 type were also resistant to\nclindamycin and erythromycin. Leukocidin genes (pvl or lukED) and hemolysin genes (hla, hld and\nhlg) were present in all of the isolates. All six isolates caused more necrosis than apoptosis in the\nhuman alveolar basal epithelial cell line A549; however, ST59/SCCmec IIIA-like isolate 6, ST30/ SCCmec IV isolate 5 with pvl genes, and MSSA ST30 isolates with tst caused greater than 40% cell\ndeath after the 4-h incubation. Regardless of the MRSA isolate and its SCCmec type or the MSSA\nisolate, the infectious spondylitis-associated S. aureus isolates differed genetically, and the pvl and\ntst genes may be important genes for cell necrosis....
Levofloxacin is a synthetic broad-spectrum antibacterial agent for oral or intravenous administration. Chemically, levofloxacin is\nthe levorotatory isomer (L-isomer) of racemate ofloxacin, a fluoroquinolone antibacterial agent. Quinolone derivatives rapidly and\nspecifically inhibit the synthesis of bacterial DNA. Levofloxacin has in vitro activity against a broad range of aerobic and anaerobic\nGram-positive and Gram-negative bacteria. However, formulation of combined poloxamers thermoregulated (as Pluronic F127)\nand levofloxacin for use in multiresistant bacterial treatment were poorly described in the current literature.Thus, the aim of the\npresent work is to characterize poloxamers for levofloxacin controlled release and their use in the treatment of multidrug bacterial\nresistance.Micelles were produced in colloidal dispersions, with a diameter between 5 and 100 nm, which formspontaneously from\namphiphilic molecules under certain conditions as concentration and temperature. Encapsulation of levofloxacin into nanospheres\nshowed efficiency and enhancement of antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, and Klebsiella\npneumoniae when compared with only levofloxacin. Furthermore, all formulations were not cytotoxic for NIH/3T3 cell lineage.\nIn conclusion, poloxamers combined with levofloxacin have shown promising results, better than alone, decreasing the minimal\ninhibitory concentration of the studied bacterialmultiresistance strains. In the future, this new formulation will be used after being\ntested in animal models in patients with resistant bacterial strains....
Background: Isothiouronium salts are well known in their variety of antimicrobials activities. The use of polymeric\nbiocides, polymers with antimicrobial activities, is expected to enhance the efficacy of some existing antimicrobial\nagents, thus minimizing the environmental problems accompanying conventional antimicrobials.\nMethods: The current manuscript describes the synthesis and characterization of crosslinked polyisothiouronium\nmethylstyrene (PITMS) nanoparticles (NPs) of narrow size distribution by dispersion co-polymerization of the monomer\nisothiouronium methylstyrene with the crosslinking monomer ethylene glycol dimetacrylate.\nResults and discussion: The effect of total monomer, crosslinker and initiator concentrations on the size and size\ndistribution of the formed NPs was also elucidated. The bactericidal activity of PITMS NPs of 67 �± 8 nm diameter\nwas illustrated for 4 bacterial pathogens: Listeria innocua, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus\naureus. In order to demonstrate the potential of these PITMS NPs as inhibitor of biofilm formation, polyethylene\nterephthalate (PET) films were thin-coated with the PITMS NPs. The formed PET/PITMS films reduced the viability of\nthe biofilm of Listeria by 2 orders of magnitude, making the coatings excellent candidates for further development of\nnon-fouling surfaces. In addition, PITMS NP coatings were found to be non-toxic in HaCaT cells.\nConclusions: The high antibacterial activity and effective inhibition of bacterial adsorption indicate the potential of\nthese nanoparticles for development of new types of antibacterial and antibiofilm additives....
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