Use of cultivation-dependent and -independent techniques to assess contamination of central venous catheters: a pilot study

<p>Abstract</p> <p>Background</p> <p>Catheters are the most common cause of nosocomial infections and are associated with increased risk of mortality, length of hospital stay and cost. Prevention of infections and fast and correct diagnosis is highly important.</p> <p>Methods</p> <p>In this study traditional semiquantitative culture-dependent methods for diagnosis of bacteria involved in central venous catheter-related infections as described by Maki were compared with the following culture-independent molecular biological methods: Clone libraries, denaturant gradient gel electrophoresis, phylogeny and fluorescence in situ hybridization.</p> <p>Results</p> <p>In accordance with previous studies, the cultivation of central venous catheters from 18 patients revealed that <it>S. epidermidis </it>and other coagulase-negative staphylococci were most abundant and that a few other microorganisms such as <it>P. aeruginosa </it>and <it>K. pneumoniae </it>occasionally were found on the catheters. The molecular analysis using clone libraries and sequencing, denaturant gradient gel electrophoresis and sequencing provided several important results. The species found by cultivation were confirmed by molecular methods. However, many other bacteria belonging to the phyla <it>Proteobacteria, Firmicutes, Actinobacteria </it>and <it>Bacteroidetes </it>were also found, stressing that only a minor portion of the species present were found by cultivation. Some of these bacteria are known to be pathogens, some have not before been described in relation to human health, and some were not closely related to known pathogens and may represent new pathogenic species. Furthermore, there was a clear difference between the bacterial species found in biofilm on the external (exluminal) and internal (luminal) side of the central venous catheter, which can not be detected by Maki's method. Polymicrobial biofilms were observed on most of the catheters and were much more common than the cultivation-dependent methods indicated.</p> <p>Conclusion</p> <p>The results show that diagnosis based on molecular methods improves the detection of microorganisms involved in central catheter-related infections. The importance of these microorganisms needs to be investigated further, also in relation to contamination risk from improper catheter handling, as only in vivo contaminants are of interest. This information can be used for development of fast and more reliable diagnostic tools, which can be used in combination with traditional methods.</p

The "forgotten" greenhouse gas emissions of our built environment will be a hard nut to crack

The "forgotten" greenhouse gas emissions of our built environment will be a hard nut to crack

The Australian industrial ecology virtual laboratory and multi-scale assessment of buildings and construction

As global population and urbanization increase, so do the direct and indirect environmental impacts of construction around the world. Low-impact products, buildings, precincts and cities are needed to mitigate the effects of building construction and use. Analysis of embodied energy and greenhouse gas (GHG) emissions across these scales is becoming more important to support this direction. The calculation of embodied impacts requires rigorous, flexible and comprehensive assessment tools. Firstly, we present the Australian Industrial Ecology Virtual Laboratory (IELab) as one such tool discussing its structure, function and wide scope of application. Secondly, we demonstrate its potential high level of resolution in a case study: assessing embodied GHG emissions in an aluminium-framed window by combining product-specific life-cycle inventory data. The input-output analysis at the core of the IELab is mathematically comprehensive in the assessment of direct and indirect impacts and the tool can be applied at a range of scales from building component, to precincts and cities, or to the entire construction industry. IELab uses a flexible formalism that enables consistent harmonisation of diverse datasets and tractable updating of input data. The emissions and energy database supporting IELab has detailed data, aligning with economic accounts and data on labour, water, materials and waste that enrich assessment across other dimensions of sustainability. IELab is a comprehensive, flexible and robust assessment tool well positioned to respond to the challenge of assessing and aiding the design of a low-impact built environment

Natural protein engineering in the Ω-loop: the role of Y221 in ceftazidime and ceftolozane resistance in Pseudomonas-derived cephalosporinase

: A wide variety of clinically observed single amino acid substitutions in the Ω-loop region have been associated with increased minimum inhibitory concentrations and resistance to ceftazidime (CAZ) and ceftolozane (TOL) in Pseudomonas-derived cephalosporinase and other class C β-lactamases. Herein, we demonstrate the naturally occurring tyrosine to histidine substitution of amino acid 221 (Y221H) in Pseudomonas-derived cephalosporinase (PDC) enables CAZ and TOL hydrolysis, leading to similar kinetic profiles (k cat = 2.3 ± 0.2 µM and 2.6 ± 0.1 µM, respectively). Mass spectrometry of PDC-3 establishes the formation of stable adducts consistent with the formation of an acyl enzyme complex, while spectra of E219K (a well-characterized, CAZ- and TOL-resistant comparator) and Y221H are consistent with more rapid turnover. Thermal denaturation experiments reveal decreased stability of the variants. Importantly, PDC-3, E219K, and Y221H are all inhibited by avibactam and the boronic acid transition state inhibitors (BATSIs) LP06 and S02030 with nanomolar IC50 values and the BATSIs stabilize all three enzymes. Crystal structures of PDC-3 and Y221H as apo enzymes and complexed with LP06 and S02030 (1.35-2.10 Å resolution) demonstrate ligand-induced conformational changes, including a significant shift in the position of the sidechain of residue 221 in Y221H (as predicted by enhanced sampling well-tempered metadynamics simulations) and extensive hydrogen bonding between the enzymes and BATSIs. The shift of residue 221 leads to the expansion of the active site pocket, and molecular docking suggests substrates orientate differently and make different intermolecular interactions in the enlarged active site compared to the wild-type enzyme

Photonik - Optische Kommunikationssysteme (Hochbitratenuebertragung). Teilvorhaben: Demonstrator fuer ein 4x10Gbit/s-TDM-Uebertragungssystem Abschlussbericht

During the development of the demonstrator for 40 Gbit/s transmission theoretical work and simulations have been performed as well as the development of the corresponding hardware. For theoretical studies a tool for simulation of optical transmission systems has been improved and enhanced in simulation capabilities. Using this tool the investigation of different physical transmission effects like polarization mode dispersion have been possible. Furthermore a flexible modular link design has been developed, showing a minimization of interaction of dispersion and self phase modulation. The realization of this design is based on a balances combination of precompensation and postcompensation of the chromatic dispersion. In the field of hardware realization on the one hand side a demonstrator for 20 Gbit/s transmission multiplexing 4 data streams of 5 Gbit/s has been built up. With this demonstrator several types of dispersion compensation have been investigated. The experience from this work has been used to realize the 40 Gbit/s demonstrator setup. Difficulties in the field of signal strength and stability of operation disabled the test of the complete system. The successful test of the components however demonstrate the validity of the concept. The realization was based on the GaAs chips developed by our project partner IAF (Fraunhofer Institut fuer angewandte Festkoerperphysik). (orig.)Available from TIB Hannover: DtF QN1(68,12) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman