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Université de Fribourg

Insights into the mechanism of photosynthetic H 2 evolution catalyzed by a heptacoordinate cobalt complex

Lucarini, Fiorella ; Fize, Jennifer ; Morozan, Adina ; Marazzi, Marco ; Natali, Mirco ; Pastore, Mariachiara ; Artero, Vincent ; Ruggi, Albert

In: Sustainable Energy & Fuels, 2020, vol. 4, no. 2, p. 589–599

H2 evolution catalyzed by a heptacoordinate complex under both electro- (1) and photo-chemical (2) conditions is analyzed in detail in order to gain insights into the mechanism of the processes. The complex shows high catalytic activity for hydrogen production in acetonitrile, in the presence of trifluoroacetic acid and triethylammonium tetrafluoroborate as proton sources. Foot-of-the-wave...

Université de Fribourg

Dimercaptosuccinic acid in combination with carbapenems against isogenic strains of Escherichia coli producing or not producing a metallo-β-lactamase in vitro and in murine peritonitis

Cheminet, G. ; de Lastours, V. ; Poirel, Laurent ; Chau, F. ; Peoc’h, K. ; Massias, L. ; Fantin, B. ; Nordmann, Patrice

In: Journal of Antimicrobial Chemotherapy, 2020, vol. 75, no. 12, p. 3593–3600

Background: Carbapenemase-producing Enterobacterales represent a major therapeutic challenge. MBLs, requiring zinc at their catalytic site, could be inhibited by meso-dimercaptosuccinic acid (DMSA), a heavy metal chelator already widely used for treating lead intoxication.Objectives: To evaluate the activity of carbapenems alone or combined with DMSA against MBL-producing Escherichia coli in...

Université de Fribourg

KPC-50 confers resistance to ceftazidime-avibactam associated with reduced carbapenemase activity

Poirel, Laurent ; Vuillemin, Xavier ; Juhas, Mario ; Masseron, Amandine ; Bechtel-Grosch, Ursina ; Tiziani, Simon ; Mancini, Stefano ; Nordmann, Patrice

In: Antimicrobial Agents and Chemotherapy, 2020, vol. 64, no. 8, p. -

KPC-50 is a KPC-3 variant identified from a Klebsiella pneumoniae clinical isolate recovered in Switzerland in 2019. Compared to KPC-3, KPC-50 shows (i) a three- amino-acid insertion (Glu-Ala-Val) between amino acids 276 and 277, (ii) an increased affinity to ceftazidime, (iii) a decreased sensitivity to avibactam, explaining the ceftazidime-avibactam resistance, and (iv) an association with a...

Université de Fribourg

Adsorption-induced kondo effect in metal-free phthalocyanine on Ag(111)

Granet, J. ; Sicot, M. ; Gerber, I. C. ; Kremer, Geoffroy ; Pierron, T. ; Kierren, B. ; Moreau, L. ; Fagot-Revurat, Y. ; Lamare, S. ; Chérioux, F. ; Malterre, D.

In: The Journal of Physical Chemistry C, 2020, vol. 124, no. 19, p. 10441–10452

We report on the formation of a two-dimensional supramolecular Kondo lattice made of organic molecules comprising only C, N, and H atoms, namely metal-free phthalocyanines 2HPc (C32H18N8), adsorbed on a Ag(111) surface. Low-temperature scanning tunneling microscopy/spectroscopy (LT-STM/STS), ultraviolet photoemission spectroscopy (UPS), and density functional theory (DFT) are used to...

Université de Fribourg

The inoculum effect of Escherichia coli expressing mcr-1 or not on colistin activity in a murine model of peritonitis

Fantin, B. ; Poujade, J. ; Grégoire, N. ; Chau, F. ; Roujansky, A. ; Kieffer, Nicolas ; Berleur, M. ; Couet, W. ; Nordmann, Patrice

In: Clinical Microbiology and Infection, 2019, vol. 25, no. 12, p. 1563.e5-1563.e8

Colistin often remains the last resort antibiotic active against carbapenemase- producing Enterobacteriaceae. However, while in vitro inoculum effect has been reported, therapeutic relevance of this phenomenon remains questioned.Methods: Ten E. coli strains were used that included the wild-type CFT073 and its transconjugant CFT073-MCR-1 and eight susceptible clinical isolates. Mice with ...

Université de Fribourg

Phenotypic, biochemical, and genetic analysis of kpc-41, a kpc-3 variant conferring resistance to ceftazidime-avibactam and exhibiting reduced carbapenemase activity

Mueller, Linda ; Masseron, Amandine ; Prod’Hom, Guy ; Galperine, Tatiana ; Greub, Gilbert ; Poirel, Laurent ; Nordmann, Patrice

In: Antimicrobial Agents and Chemotherapy, 2019, vol. 63, no. 12, p. -

A novel KPC variant, KPC-41, was identified in a Klebsiella pneumoniae clinical isolate from Switzerland. This β-lactamase possessed a 3-amino-acid insertion (Pro- Asn-Lys) located between amino acids 269 and 270 compared to the KPC-3 amino acid sequence. Cloning and expression of the blaKPC-41 gene in Escherichia coli, followed by determination of MIC values and kinetic parameters, showed...