Fatal respiratory infection due to ST308 VIM-1-producing Pseudomonas aeruginosa in a lung transplant recipient : case report and review of the literature

Background: Data regarding the prevalence of metallo-\u3b2-lactamases (MBLs) among Pseudomonas aeruginosa isolates in cystic fibrosis patients are scarce. Furthermore, there is limited knowledge on the effect of MBL production on patient outcomes. Here we describe a fatal respiratory infection due to P. aeruginosa producing VIM-type MBLs in a lung transplant recipient and the results of the subsequent epidemiological investigation. Case presentation: P. aeruginosa isolates collected in the index patient and among patients temporally or spatially linked with the index patient were analyzed in terms of antibiotic susceptibility profile and MBL production. Whole-genome sequencing and phylogenetic reconstruction were also performed for all P. aeruginosa isolates producing VIM-type MBLs. A VIM-producing P. aeruginosa strain was identified in a lung biopsy of a lung transplant recipient with cystic fibrosis. The strain was VIM-1-producer and belonged to the ST308. Despite aggressive treatment, the transplant patient succumbed to the pulmonary infection due to the ST308 strain. A VIM-producing P. aeruginosa strain was also collected from the respiratory samples of a different cystic fibrosis patient attending the same cystic fibrosis center. This isolate harbored the blaVIM-2 gene and belonged to the clone ST175. This patient did not experience an adverse outcome. Conclusions: This is the first description of a fatal infection due to P. aeruginosa producing VIM-type MBLs in a lung transplant recipient. The circulation of P. aeruginosa isolates harboring MBLs pose a substantial risk to the cystic fibrosis population due to the limited therapeutic options available and their spreading potential

The role of Background Independence for Asymptotic Safety in Quantum Einstein Gravity

We discuss various basic conceptual issues related to coarse graining flows in quantum gravity. In particular the requirement of background independence is shown to lead to renormalization group (RG) flows which are significantly different from their analogs on a rigid background spacetime. The importance of these findings for the asymptotic safety approach to Quantum Einstein Gravity (QEG) is demonstrated in a simplified setting where only the conformal factor is quantized. We identify background independence as a (the ?) key prerequisite for the existence of a non-Gaussian RG fixed point and the renormalizability of QEG.Comment: 2 figures. Talk given by M.R. at the WE-Heraeus-Seminar "Quantum Gravity: Challenges and Perspectives", Bad Honnef, April 14-16, 2008; to appear in General Relativity and Gravitatio

Determination of aspartate aminotransferase activity by high performance liquid chromatography

A sensitive and reproducible assay of aspartate aminotransferase activity based on UV detection of the reaction products after their separation by HPLC is described. The main advantage is the direct measurement of the enzyme activity as micromoles of product (glutamate) formed within a known period of time without any coupled reaction. Further, with the chromatographic method, all components of the reaction mixture are identified, allowing the reaction course to be controlled and the possible presence of side-reactions to be monitored

High Performance Liquid Chromatography Assay for Alanine Amino Transferase

An improved method of alanine-amino transferase determination is proposed. The reaction is carried out with alanine and 2-oxoglutarate as substrates and analysis is by HPLC on a reversed-phase chromatographic system using a Ca8 column and tetrabutylammonium phosphate in Phosphate buffer (pH 7.0)-acetonitrile as mobile phase. The enzyme activity was determined by directly following the formation of pyruvic acid without employing any sec- Ondary reaction, which is necessary in the spectrophotometric method. The detection limit of pyruvic acid is 10 Pmole/al-I and the standard deviation for the enzymatic activity of standard solutions is 5.4%. Furthermore under the chromatographic conditions selected it is possible to detect the presence of some intermediate species

Enantioselective transport of D,L-phenylalanine and D,L-phenylglycine through a bulk liquid membrane containing cinchona alkaloid derivatives as chiral selectors

Different cinchona derivatives were tested as chiral mobile carriers for enantioselective transport of D,L-phenylglycine and D,L-phenylalanine through a bulk organic liquid membrane (BLM). The effects of several parameters such as carrier nature, membrane solvent, buffer, solute and carrier concentrations on BLM enrichment were evaluated. Only D,L-phenylglycine is subjected to enantioselective transport at a certain degree; the maximum enantioselectivity ratio (the initial transport rates of the L-enantiomer relative to the antipode) was reached by employing O-allyl-N-(9-anthracenylmethyl) cinchonidinium bromide as carrier. In all cases the highest selectivity was observed during the initial stages of the process, indicating the rate of amino acid release from the source phase (SP) to the membrane organic phase (MP) as the driving factor. Chiral enrichment appeared to depend on thermodynamic factors more than on kinetic ones, since the complex formation was observed at (SP)/MP) interface, while complex decomposition was evidenced at (RP)/(MP) interface, where RP is receiving phase. The last phenomenon was promoted by H+ ions present in the RP

High-performance liquid chromatographic resolution of enantiomers on chiral amine-bonded silica gel

A chiral stationary phase with an immobilized, optically active diamine was prepared for the separation of enantiomers. The synthesis of the phase was carried out by bonding (–)trans-1,2-cyclohexanediamine to microparticulate silica gel through the coupling agent 3-glycidoxypropylsilane. The resolution of the racemic compounds catechin, 2,2-dihydroxy-1,1binaphthyl and trans-1,2-cyclohexandiol, is reporte

New method for guanase activity measurement by high performance liquid chromatography

A rapid isocratic high-performance liquid chromatographic method for the determination of guanase (EC 3.5.4.3) activity is proposed. The method is highly reproducible, with a coefficient of variation of less than 1%, and requires only ca. 10 min for a complete chromatographic separation of the enzyme reaction mixture. The method allows the detection of nanomolar changes in the concentrations of both the substrate and the product, and does not require additional reactions or sample pretreatment. Kinetic studies with the proposed method showed the guanase activity to have an apparent Michaelis constant of 13.3 and 8.5 microM, and a maximum rate of 1.95 and 3.84 pmol/min per mg protein at 37 degrees C, in Tris-HCl and phosphate buffer, respectivel