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Markus Nagl - One of the best experts on this subject based on the ideXlab platform.

  • Bactericidal and Fungicidal Activity of N-Chlorotaurine Is Enhanced in Cystic Fibrosis Sputum Medium.
    Antimicrobial Agents and Chemotherapy, 2017
    Co-Authors: Martina Gruber, Markus Nagl, Ivan Moser, Michaela Lackner
    Abstract:

    Lung infections with multiresistant pathogens are a major problem among patients suffering from cystic fibrosis (CF). N-Chlorotaurine (NCT), a microbicidal active Chlorine Compound with no development of resistance, is well tolerated upon inhalation. The aim of this study was to investigate the in vitro bactericidal and fungicidal activity of NCT in artificial sputum medium (ASM), which mimics the composition of CF mucus. The medium was inoculated with bacteria (Staphylococcus aureus, including some methicillin-resistant S. aureus [MRSA] strains, Pseudomonas aeruginosa, and Escherichia coli) or spores of fungi (Aspergillus fumigatus, Aspergillus terreus, Candida albicans, Scedosporium apiospermum, Scedosporium boydii, Lomentospora prolificans, Scedosporium aurantiacum, Scedosporium minutisporum, Exophiala dermatitidis, and Geotrichum sp.), to final concentrations of 107 to 108 CFU/ml. NCT was added at 37°C, and time-kill assays were performed. At a concentration of 1% (10 mg/ml, 55 mM) NCT, bacteria and spores were killed within 10 min and 15 min, respectively, to the detection limit of 102 CFU/ml (reduction of 5 to 6 log10 units). Reductions of 2 log10 units were still achieved with 0.1% (bacteria) and 0.3% (fungi) NCT, largely within 10 to 30 min. Measurements by means of iodometric titration showed oxidizing activity for 1, 30, 60, and >60 min at concentrations of 0.1%, 0.3%, 0.5%, and 1.0% NCT, respectively, which matches the killing test results. NCT demonstrated broad-spectrum microbicidal activity in the milieu of CF mucus at concentrations ideal for clinical use. The microbicidal activity of NCT in ASM was even stronger than that in buffer solution; this was particularly pronounced for fungi. This finding can be explained largely by the formation, through transhalogenation, of monochloramine, which rapidly penetrates pathogens.

  • Bactericidal Activity of N-Chlorotaurine against Biofilm-Forming Bacteria Grown on Metal Disks
    Antimicrobial agents and chemotherapy, 2014
    Co-Authors: Débora C. Coraça-huber, Christoph G. Ammann, Manfred Fille, Johann Hausdorfer, Michael Nogler, Markus Nagl
    Abstract:

    Many orthopedic surgeons consider surgical irrigation and debridement with prosthesis retention as a treatment option for postoperative infections. Usually, saline solution with no added antimicrobial agent is used for irrigation. We investigated the activity of N-chlorotaurine (NCT) against various biofilm-forming bacteria in vitro and thereby gained significant information on its usability as a soluble and well-tolerated active Chlorine Compound in orthopedic surgery. Biofilms of Staphylococcus aureus were grown on metal alloy disks and in polystyrene dishes for 48 h. Subsequently, they were incubated for 15 min to 7 h in buffered solutions containing therapeutically applicable concentrations of NCT (1%, 0.5%, and 0.1%; 5.5 to 55 mM) at 37°C. NCT inactivated the biofilm in a time- and dose-dependent manner. Scanning electron microscopy revealed disturbance of the biofilm architecture by rupture of the extracellular matrix. Assays with reduction of carboxanilide (XTT) showed inhibition of the metabolism of the bacteria in biofilms. Quantitative cultures confirmed killing of S. aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa biofilms on metal alloy disks by NCT. Clinical isolates were slightly more resistant than ATCC type strains, but counts of CFU were reduced at least 10-fold by 1% NCT within 15 min in all cases. NCT showed microbicidal activity against various bacterial strains in biofilms. Whether this can be transferred to the clinical situation should be the aim of future studies.

  • In vitro activity of -chlorotaurine (NCT) in combination with NHCl against
    International Journal of Antimicrobial Agents, 2011
    Co-Authors: Ursula Fürnkranz, Markus Nagl, Waldemar Gottardi, Michael Duchêne, Horst Aspöck, Julia Walochnik
    Abstract:

    Trichomoniasis, caused by the protozoan , is usually treated with metronidazole, however resistance is on the rise. In this study, -chlorotaurine (NCT), a new endogenous mild active Chlorine Compound for topical use, killed in vitro within 15min of treatment at a concentration of 55mM (1%), which is well tolerated by human tissue. The activity of NCT was further enhanced by addition of ammonium chloride (NHCl). A combination of 5.5mM (0.1%) NCT plus 19mM (0.1%) NHCl killed 100% of trichomonads within 5min.

  • Chlorine covers on living bacteria: the initial step in antimicrobial action of active Chlorine Compounds
    The Journal of antimicrobial chemotherapy, 2005
    Co-Authors: Waldemar Gottardi, Markus Nagl
    Abstract:

    Objectives: Although active Chlorine Compounds are well-known antimicrobial agents in human medicine, their initial steps of action have not been completely clarified. Using N-chlorotaurine (NCT), an endogenous mild representative, we observed persisting oxidation capacity affixed to bacteria. It was the aim of this study to investigate this ‘Chlorine cover’. Methods: Pathogens were incubated in NCT, which was subsequently washed off. The oxidation capacity on the bacterial surface was measured photometrically. Results: Superficial chlorination in the form of covalent N‐Cl bonds to Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa and Candida albicans could be attached before killing took place. For S. aureus, 3 min incubation with NCT produced a cover of 3.3 3 10 216 mol Cl 1 /cfu, while the cfu count was reduced by only 26%. The kind of microorganism, coating time, pH, buffer system and, basically, the Chlorine Compound, influenced the cover strength. The relative cover strength on S. aureus by NCT, chloramine T, sodium dichloro-isocyanurate or N,N-dichlorotaurine was 1:15.7:38.7:0.24. Chlorine covers were surprisingly stable and could be detected for 3 h at 20 8 C( >8 h at 18C), even without a reduction of cfu. However, addition of 5% ammonium chloride caused a rapid loss of viability, explained by formation of highly bactericidal NH2Cl, an effect that resembles the ignition of a time-bomb. Conclusions: The Chlorine cover can be regarded as the first sign of interaction between chlorinating agent and microorganism, and may explain the non-lethal features of postantibiotic effect and attenuation of bacterial virulence. Furthermore, it may be a decisive step in bacterial inactivation by the myeloperoxidase-hypochlorite system in innate immunity.

Sherwood F Rowland - One of the best experts on this subject based on the ideXlab platform.

  • seasonal variations in the atmospheric distribution of a reactive Chlorine Compound tetrachloroethene ccl2 ccl2
    Geophysical Research Letters, 1995
    Co-Authors: Charles Wang, D R Blake, Sherwood F Rowland
    Abstract:

    Tropospheric mixing ratios of CCl2=CCl2 were measured at remote surface locations in the Pacific between 71°N and 47°S during September and December of 1989, and March and June of 1990. The observed gradient of decreasing concentrations from the northern to southern hemisphere, and very low concentrations in the southern hemisphere throughout the year, indicates a predominant input from the northern hemisphere. Our seasonal measurements in the northern hemisphere showed maximum CCl2=CCl2 concentrations occurring in the late winter and minimum concentrations occurring in the late summer. This distinct seasonal variation is strongly coupled to the atmospheric abundance of hydroxyl radical, the only important species responsible for CCl2=CCl2 removal. Using the estimated global CCl2=CCl2 emissions the lifetime is calculated to be about 5.4 months which is in good agreement with the 4.0 month estimate obtained from the inverse ratio of its measured hydroxyl reaction rate constant compared with that of methylchloroform (CH3CCl3).

Waldemar Gottardi - One of the best experts on this subject based on the ideXlab platform.

  • In vitro activity of -chlorotaurine (NCT) in combination with NHCl against
    International Journal of Antimicrobial Agents, 2011
    Co-Authors: Ursula Fürnkranz, Markus Nagl, Waldemar Gottardi, Michael Duchêne, Horst Aspöck, Julia Walochnik
    Abstract:

    Trichomoniasis, caused by the protozoan , is usually treated with metronidazole, however resistance is on the rise. In this study, -chlorotaurine (NCT), a new endogenous mild active Chlorine Compound for topical use, killed in vitro within 15min of treatment at a concentration of 55mM (1%), which is well tolerated by human tissue. The activity of NCT was further enhanced by addition of ammonium chloride (NHCl). A combination of 5.5mM (0.1%) NCT plus 19mM (0.1%) NHCl killed 100% of trichomonads within 5min.

  • Chlorine covers on living bacteria: the initial step in antimicrobial action of active Chlorine Compounds
    The Journal of antimicrobial chemotherapy, 2005
    Co-Authors: Waldemar Gottardi, Markus Nagl
    Abstract:

    Objectives: Although active Chlorine Compounds are well-known antimicrobial agents in human medicine, their initial steps of action have not been completely clarified. Using N-chlorotaurine (NCT), an endogenous mild representative, we observed persisting oxidation capacity affixed to bacteria. It was the aim of this study to investigate this ‘Chlorine cover’. Methods: Pathogens were incubated in NCT, which was subsequently washed off. The oxidation capacity on the bacterial surface was measured photometrically. Results: Superficial chlorination in the form of covalent N‐Cl bonds to Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa and Candida albicans could be attached before killing took place. For S. aureus, 3 min incubation with NCT produced a cover of 3.3 3 10 216 mol Cl 1 /cfu, while the cfu count was reduced by only 26%. The kind of microorganism, coating time, pH, buffer system and, basically, the Chlorine Compound, influenced the cover strength. The relative cover strength on S. aureus by NCT, chloramine T, sodium dichloro-isocyanurate or N,N-dichlorotaurine was 1:15.7:38.7:0.24. Chlorine covers were surprisingly stable and could be detected for 3 h at 20 8 C( >8 h at 18C), even without a reduction of cfu. However, addition of 5% ammonium chloride caused a rapid loss of viability, explained by formation of highly bactericidal NH2Cl, an effect that resembles the ignition of a time-bomb. Conclusions: The Chlorine cover can be regarded as the first sign of interaction between chlorinating agent and microorganism, and may explain the non-lethal features of postantibiotic effect and attenuation of bacterial virulence. Furthermore, it may be a decisive step in bacterial inactivation by the myeloperoxidase-hypochlorite system in innate immunity.

Charles Wang - One of the best experts on this subject based on the ideXlab platform.

  • seasonal variations in the atmospheric distribution of a reactive Chlorine Compound tetrachloroethene ccl2 ccl2
    Geophysical Research Letters, 1995
    Co-Authors: Charles Wang, D R Blake, Sherwood F Rowland
    Abstract:

    Tropospheric mixing ratios of CCl2=CCl2 were measured at remote surface locations in the Pacific between 71°N and 47°S during September and December of 1989, and March and June of 1990. The observed gradient of decreasing concentrations from the northern to southern hemisphere, and very low concentrations in the southern hemisphere throughout the year, indicates a predominant input from the northern hemisphere. Our seasonal measurements in the northern hemisphere showed maximum CCl2=CCl2 concentrations occurring in the late winter and minimum concentrations occurring in the late summer. This distinct seasonal variation is strongly coupled to the atmospheric abundance of hydroxyl radical, the only important species responsible for CCl2=CCl2 removal. Using the estimated global CCl2=CCl2 emissions the lifetime is calculated to be about 5.4 months which is in good agreement with the 4.0 month estimate obtained from the inverse ratio of its measured hydroxyl reaction rate constant compared with that of methylchloroform (CH3CCl3).

Ravi Kolhatkar - One of the best experts on this subject based on the ideXlab platform.

  • Assessment of anaerobic biodegradation of bis(2-chloroethyl) ether in groundwater using carbon and Chlorine Compound-specific isotope analysis
    The Science of the total environment, 2018
    Co-Authors: Daniel C. Segal, Tomasz Kuder, Ravi Kolhatkar
    Abstract:

    Abstract Carbon and Chlorine Compound specific isotope analysis (CSIA) of bis(2-chloroethyl) ether (BCEE) was performed to distinguish the primary processes contributing to observed concentration reductions in an anaerobic groundwater plume. Laboratory microcosms were constructed to demonstrate and obtain isotopic enrichment factors and dual-element CSIA trends from two potential transformation processes (1) anaerobic biodegradation using saturated sediment samples from the field site (eC = − 14.8 and eCl = − 5.0) and (2) abiotic reactions with sulfide nucleophiles in water (eC = − 12.8 and eCl = − 5.0). The results suggested a nucleophilic, SN2-type dechlorination as the mechanism of biodegradation of BCEE. Identical dual-element CSIA trends observed in the field and in the microcosm samples suggested that the same degradation mechanism was responsible for BCEE degradation in the field. While biodegradation was the likely dominant mechanism of BCEE mass destruction in the aquifer, potential contribution of abiotic hydrolysis to the net budget of degradation could not be confidently excluded. To our knowledge, this is the first unequivocal demonstration of BCEE biodegradation at a field site.